Peter Davies, PhD: A Life Committed to Changing the Face of Alzheimer’s
Toni Saari, Anne Koivisto, Taina Hintsa, Tuomo Hänninen, Ilona Hallikainen
Psychometric Properties of the Neuropsychiatric Inventory: A Review
Abstract: Neuropsychiatric symptoms cause a significant burden to individuals with neurocognitive disorders and their families. Insights into the clinical associations, neurobiology, and treatment of these symptoms depend on informant questionnaires, such as the commonly used Neuropsychiatric Inventory (NPI). As with any scale, the utility of the NPI relies on its psychometric properties, but the NPI faces unique challenges related to its skip-question and scoring formats. In this narrative review, we examined the psychometric properties of the NPI in a framework including properties pertinent to construct validation, and health-related outcome measurement in general. We found that aspects such as test-retest and inter-rater reliability are major strengths of the NPI in addition to its flexible and relatively quick administration. These properties are desired in clinical trials. However, the reported properties appear to cover only some of the generally examined psychometric properties, representing perhaps necessary but insufficient reliability and validity evidence for the NPI. The psychometric data seem to have significant gaps, in part because small sample sizes in the relevant studies have precluded more comprehensive analyses. Regarding construct validity, only one study has examined structural validity with the NPI subquestions. Measurement error was not assessed in the reviewed studies. For future validation, we recommend using data from all subquestions, collecting larger samples, paying specific attention to construct validity and formulating hypotheses a priori. Because the NPI is an outcome measure of interest in clinical trials, examining measurement error could be of practical importance.
Anticoagulants for Treatment of Alzheimer’s Disease
Abstract: Alzheimer’s disease (AD) is a multifactorial syndrome with a plethora of progressive, degenerative changes in the brain parenchyma, but also in the cerebrovascular and hemostatic system. A therapeutic approach for AD is reviewed, which is focused on the role of amyloid-β protein (Aβ) and fibrin in triggering intra-brain vascular dysfunction and connected, cognitive decline. It is proposed that direct oral anticoagulants (DOACs) counteract Aβ-induced pathological alterations in cerebral blood vessels early in AD, a condition, known as cerebral amyloid angiopathy (CAA). By inhibiting thrombin for fibrin formation, anticoagulants can prevent accumulations of proinflammatory thrombin and fibrin, and deposition of degradation-resistant, Aβ-containing fibrin clots. These fibrin-Aβ clots are found in brain parenchyma between neuron cells, and in and around cerebral blood vessels in areas of CAA, leading to decreased cerebral blood flow. Consequently, anticoagulant treatment could reduce hypoperfusion and restricted supply of brain tissue with oxygen and nutrients. Concomitantly, hypoperfusion-enhanced neurodegenerative processes, such as progressive Aβ accumulation via synthesis and reduced perivascular clearance, neuroinflammation, and synapse and neuron cell loss, could be mitigated. Given full cerebral perfusion and reduced Aβ- and fibrin-accumulating and inflammatory milieu, anticoagulants could be able to decrease vascular-driven progression in neurodegenerative and cognitive changes, present in AD, when treated early, therapeutically, or prophylactically.
Simon Gelman, Jonathan Palma, Afshin Ghavami
Axonal Conduction Velocity in CA1 Area of Hippocampus Is Reduced in Mouse Models of Alzheimer’s Disease
Abstract: The timing of action potentials arrival at synaptic terminals partially determines integration of synaptic inputs and is important for information processing in the CNS. Therefore, axonal conduction velocity (VC) is a salient parameter, influencing the timing of synaptic inputs. Even small changes in VC may disrupt information coding in networks requiring accurate timing. We recorded compound action potentials in hippocampal slices to measure VC in three mouse models of Alzheimer’s disease. We report an age-dependent reduction in VC in area CA1 in two amyloid-β precursor protein transgenic mouse models, line 41 and APP/PS1, and in a tauopathy model, rTg4510.
Yi Wang, Liyu Li, Shuangyue Tian, Jie Wu, Zhiwen Wang
Development and Psychometrics Test of Home Environment Assessment Checklist for Community-Dwelling Older Adults with Dementia
Abstract: Background: Home environment is a core domain in the care of community-dwelling older adults with dementia, but there is no suitable instrument to measure it in China. Objective: To develop and psychometrically test the home environment assessment checklist for community-dwelling older adults with dementia. Methods: A three-step process was performed to develop and test this instrument: 1) based on the evidence-based theory, the checklist was summarized as the main points of evidence from living environment settings among older adults with dementia, 2) the draft tool was assigned to an iterative process of evaluation by a panel of examiners consisting of experts from treatment, nursing and caring, people with dementia and their caregivers, 3) inter-rater reliability and internal consistency were calculated with a sample of 348 caregivers of the older adults with dementia. Results: The HEAC consists of 71 items in domains addressing safety, stability/familiarity, visual cues, and sensory stimulation. Psychometric evaluation showed that this tool demonstrated sound reliability and validity. Content validity was 0.969 which was established by a panel of experts (n=10). Inter-rater reliability of two researchers was 0.978, and 0.848 for researchers and caregivers. Test-retest reliability was excellent (ICC=0.757-0.877) in community-dwelling older adults with dementia 2 week apart. Conclusion: The HEAC is a new tool to help collect the reliable information on the barriers and facilitators of home environment for community-dwelling older adults with dementia and to precipitate the home modification process to improve the quality of care for people with dementia and their caregivers in daily life.
Kristof Van Kolen*, Thomas J. Malia*, Clara Theunis, Rupesh Nanjunda, Alexey Teplyakov, Robin Ernst, Sheng-Jiun Wu, Jinquan Luo, Marianne Borgers, Marc Vandermeeren, Astrid Bottelbergs, Cindy Wintmolders, Eilyn Lacy, Hervé Maurin, Peter Larsen, Roland Willems, Tom Van De Casteele, Gallen Triana-Baltzer, Randy Slemmon, Wendy Galpern, John Q. Trojanowski, Hong Sun, Marc H. Mercken *These authors contributed equally to this work.
Discovery and Functional Characterization of hPT3, a Humanized Anti-Phospho Tau Selective Monoclonal Antibody
Abstract: Background: As a consequence of the discovery of an extracellular component responsible for the progression of tau pathology, tau immunotherapy is being extensively explored in both preclinical and clinical studies as a disease modifying strategy for the treatment of Alzheimer’s disease. Objective: Describe the characteristics of the anti-phospho (T212/T217) tau selective antibody PT3 and its humanized variant hPT3. Methods: By performing different immunization campaigns, a large collection of antibodies has been generated and prioritized. In depth, in vitro characterization using surface plasmon resonance, phospho-epitope mapping, and X-ray crystallography experiments were performed. Further characterization involved immunohistochemical staining on mouse- and human postmortem tissue and neutralization of tau seeding by immunodepletion assays. Results and Conclusion: Various in vitro experiments demonstrated a high intrinsic affinity for PT3 and hPT3 for AD brain-derived paired helical filaments but also to non-aggregated phospho (T212/T217) tau. Further functional analyses in cellular and in vivo models of tau seeding demonstrated almost complete depletion of tau seeds in an AD brain homogenate. Ongoing trials will provide the clinical evaluation of the tau spreading hypothesis in Alzheimer’s disease.
Gallen Triana-Baltzer, Kristof Van Kolen, Clara Theunis, Setareh Moughadam, Randy Slemmon, Marc Mercken, Wendy Galpern, Hong Sun, Hartmuth Kolb
Development and Validation of a High Sensitivity Assay for Measuring p217+tau in Cerebrospinal Fluid
Abstract: Background: Early and accurate detection and staging is critical to managing Alzheimer’s disease (AD) and supporting clinical trials. Cerebrospinal fluid (CSF) biomarkers for amyloid-β peptides, tau species, and various neurodegenerative and inflammatory analytes are leading the way in this regard, yet there is room for improved sensitivity and specificity. In particular tau is known to be present in many different fragments, conformations, and post-translationally modified forms. While the exact tau species that might best reflect AD pathology is unknown, a growing body of evidence suggests that forms with high levels of phosphorylation in the mid-region may be especially enriched in AD. Objective: Develop an assay for measuring p217tau in CSF. Methods: Here we describe the development and validation of a novel sELISA for measuring CSF tau species containing phosphorylation at threonines 212 & 217, aka p217+tau, using the PT3 antibody. Results: While the analyte is present at extremely low levels the assay is sufficiently sensitive and specific to quantitate p217+tau with excellent precision, accuracy, and dilution linearity, allowing good differentiation between diagnostic subgroups. The p217+tau measurements appear to track AD pathology better than the commonly used p181tau epitope, suggesting superior diagnostic and staging performance. Finally, the assay can also be configured to differentiate antibody-bound versus antibody-free tau, and therefore can be used to measure target engagement by p217+tau-targeting immunotherapeutics. Conclusion: The assay for measuring p217+tau described here is highly sensitive, accurate, precise, dilution linear, and shows good potential for identifying and staging AD.
Marie-Louise Montandon*, François R. Herrmann*, Valentina Garibotto, Cristelle Rodriguez, Sven Haller, Panteleimon Giannakopoulos *These authors contributed equally to this work.
Microbleeds and Medial Temporal Atrophy Determine Cognitive Trajectories in Normal Aging: A Longitudinal PET-MRI Study
Abstract: Background: The cognitive trajectories in normal aging may be affected by medial temporal atrophy (MTA) and amyloid burden, as well as vascular pathologies such as cortical microbleeds (CMB) and white matter hyperintensities (WMH). Objective: We addressed here the role of imaging markers in their prediction in a real-world situation. Methods: We performed a 4.5-year longitudinal study in 90 older community-dwellers coupling two neuropsychological assessments, MTA estimated with the Schelten’s scale, number of CMB, and WMH evaluated with the Fazekas score at inclusion and follow-up, visual rating of amyloid PET and glucose hypometabolism at follow-up, and APOE genotyping. Regression models were built to explore the association between the continuous cognitive score (CCS) and imaging parameters. Results: The number of strictly lobar CMB at baseline (4 or more) was related to a 5.5-fold increase of the risk of cognitive decrement. This association persisted in multivariable models explaining 10.6% of the CCS decrease variance. MTA, and Fazekas score at baseline and amyloid positivity or abnormal FDG PET, were not related to the cognitive outcome. The increase of right MTA at follow-up was the only correlate of CCS decrease both in univariate and multivariable models explaining 9.2% of its variance. Conclusion: The present data show that the accumulation of more than four CMB is associated with significant cognitive decrement over time in highly educated elderly persons. They also reveal that the progressive deterioration of cognitive performance within the age-adjusted norms is also related to the increase of visually assessed MTA.
Theresa Müller, Nicola M. Payton, Grégoria Kalpouzos, Frank Jessen, Giulia Grande, Lars Bäckman, Erika J. Laukka
Cognitive, Genetic, Brain Volume, and Diffusion Tensor Imaging Markers as Early Indicators of Dementia
Abstract: Background: Although associated with dementia and cognitive impairment, microstructural white matter integrity is a rarely used marker of preclinical dementia. Objective: We aimed to evaluate the individual and combined effects of multiple markers, with special focus on microstructural white matter integrity, in detecting individuals with increased dementia risk. Methods: A dementia-free subsample (n = 212, mean age = 71.33 years) included in the population-based Swedish National Study on Aging and Care (SNAC-K) underwent magnetic resonance imaging (T1-weighted, fluid-attenuated inversion recovery, diffusion tensor imaging), neuropsychological testing (perceptual speed, episodic memory, semantic memory, letter and category fluency), and genotyping (APOE). Incident dementia was assessed during six years of follow-up. Results: A global model (global cognition, APOE, total brain tissue volume: AUC = 0.920) rendered the highest predictive value for future dementia. Of the models based on specific markers, white matter integrity of the forceps major tract was included in the most predictive model, in combination with perceptual speed and hippocampal volume (AUC = 0.911). Conclusion: Assessment of microstructural white matter integrity may improve the early detection of dementia, although the added benefit in this study was relatively small.
Roberto Santangelo, Su-Chun Huang, Maria Paola Bernasconi, Monica Falautano, Giancarlo Comi, Giuseppe Magnani, Letizia Leocani
Neuro-Retina Might Reflect Alzheimer’s Disease Stage
Abstract: Background: Alzheimer’s disease (AD) pathological hallmarks were found in retinas of AD patients. Several studies showed a significant reduction of neuro-retina thickness measured through optical coherence tomography (OCT) in AD patients, but possible correlations between retina morphology, cognition, and cerebrospinal fluid (CSF) AD biomarkers (Aβ42, t-tau, and p-tau) have been poorly investigated so far. Objective: In the present cross-sectional study, we measured the thickness of neuro-retinal layers through OCT searching for possible correlations with patients’ cognitive performances and CSF AD biomarkers. Methods: 137 consecutive subjects [43 with AD, 37 with mild cognitive impairment (MCI), and 57 healthy controls (HC)], received an OCT scan acquisition to measure the peripapillary retinal nerve fiber layer (RNFL) thickness. In a subsample of 21 AD, 18 MCI, and 18 HC, the macular volume of ganglion cell layer (GCL), inner plexiform layer (IPL), and inner nuclear layer was computed. A comprehensive neuropsychological assessment and CSF AD biomarkers’ concentrations were available in AD and MCI patients. Results: Peripapillary RNFL, global, and in superior quadrant was significantly thinner in AD and MCI patients when compared to HC, while macular GCL volume was significantly reduced only in AD. RNFL thickness in nasal and inferior quadrants was correlated with single CSF AD biomarker concentrations, but no differences were found in retina morphology depending on the presence of a CSF profile typical for AD. Memory performances were positively associated with GCL and IPL volume. Conclusion: Our findings might propose OCT as a reliable and easy to handle tool able to detect neuro-retinal atrophy in AD in relation with cognitive performances.
Claudia Olive, Laura Ibanez, Fabiana H. Geraldo Farias, Fengxian Wang, John P. Budde, Joanne B. Norton, Jen Gentsch, John C. Morris, Zeran Li, Umber Dube, Jorge Del-Aguila, Kristy Bergmann, Joseph Bradley, Bruno A. Benitez, Oscar Harari, Anne Fagan, Beau Ances, Carlos Cruchaga*, Maria Victoria Fernandez* (Handling Associate Editor: M. Arfan Ikram) *These authors contributed equally to this work.
Examination of the Effect of Rare Variants in TREM2, ABI3, and PLCG2 in LOAD Through Multiple Phenotypes
Abstract: Background: Rare variants in PLCG2 (p.P522R), ABI3 (p.S209F), and TREM2 (p.R47H, p.R62H) have been associated with late onset Alzheimer’s disease (LOAD) risk in Caucasians. After the initial report, several studies have found positive results in cohorts of different ethnic background and with different phenotype. Objective: In this study, we aim to evaluate the association of rare coding variants in PLCG2, ABI3, and TREM2 with LOAD risk and their effect at different time points of the disease. Methods: We used a European American cohort to assess the association of the variants prior onset (using CSF Aβ42, tau, and pTau levels, and amyloid imaging as endophenotypes) and after onset (measured as rate of memory decline). Results: We confirm the association with LOAD risk of TREM2 p.R47H, p.R62H and ABI3 p.S209F variants, and the protective effect of PLCG2 p.P522R. In addition, ABI3 and TREM2 gene-sets showed significant association with LOAD risk. TREM2 p.R47H and PLCG2 p.P522R variants were also statistically associated with increase of amyloid imaging and AD progression, respectively. We did not observe any association of ABI3 p.S209F with any of the other AD endophenotypes. Conclusion: The results of this study highlight the importance of including biomarkers and alternative phenotypes to better understand the role of novel candidate genes with the disease.
Prasad R. Padala, Eugenia M. Boozer, Shelly Y. Lensing, Christopher M. Parkes, Cassandra R. Hunter, Richard A. Dennis, Ricardo Caceda, Kalpana P. Padala (Handling Associate Editor: Krista Lanctôt)
Neuromodulation for Apathy in Alzheimer’s Disease: A Double-Blind, Randomized, Sham-Controlled Pilot Study
Abstract: Background: Apathy, a profound loss of motivation, initiation, and goal directed cognition, is a common comorbidity of Alzheimer’s disease (AD). The presence of apathy is associated with rapid progression of AD, long-term impairment, disability, and higher mortality. Pharmacological treatments of apathy are limited. Objective: The primary objective was to evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) for apathy in AD. Methods: A randomized, double-blind, parallel-arm, sham-controlled pilot study was conducted in subjects with AD and apathy (N=20). Subjects were randomized to rTMS or sham treatment (5 days/week) for four weeks. Primary outcome, apathy evaluation scale-clinician version (AES-C), and secondary outcome measures, modified-Mini Mental State Examination (3MS), instrumental activities of daily living (IADL), and clinical global impression (CGI), were assessed at baseline and four weeks. Follow-up visits were conducted at 8 and 12 weeks to test the durability of effects of intervention. Results: Mean age was 77.3 (±7.2) years, 80% were Caucasians and 10% were females. After adjusting for baseline, there was a significantly greater improvement in the AES-C with rTMS compared to sham treatment (-10.1 (-15.9 to -4.3); t(16)=-3.69; p=0.002) at 4 weeks. There was also significantly greater improvement in 3MS (6.9 (1.7 to 12.0); t(15)=2.85; p=0.012), IADL (3.4 (1.0 to 5.9); χ21=7.72; p=0.006), CGI-S (1.4 (0.5 to 2.3), t(16)=3.29; p=0.005), and CGI-I (-2.56 (-3.5 to -1.6), t(17)=-5.72; p<0.001) for rTMS compared to the sham at 4 weeks. The effects of rTMS were durable at 12 weeks. Conclusion: rTMS may be safely used in subjects with AD and may improve apathy, function, and some aspects of cognition.
Shanshan Chen*, Wenwen Xu*, Chen Xue, Guanjie Hu, Wenying Ma, Wenzhang Qi, Lin Dong, Xingjian Lin, Jiu Chen *These authors contributed equally to this work.
Voxelwise Meta-Analysis of Gray Matter Abnormalities in Mild Cognitive Impairment and Subjective Cognitive Decline Using Activation Likelihood Estimation
Abstract: Background: Voxel-based morphometry studies have not yielded consistent results among patients with mild cognitive impairment (MCI) and subjective cognitive decline (SCD). Objective: Therefore, we aimed to conduct a meta-analysis of gray matter (GM) abnormalities acquired from these studies to determine their respective neuroanatomical changes. Methods: We systematically searched for voxel-based whole-brain morphometry studies that compared MCI or SCD subjects with healthy controls in PubMed, Web of Science, and EMBASE databases. We used the coordinate-based method of activation likelihood estimation to determine GM changes in SCD, MCI, and MCI sub-groups (amnestic MCI and non-amnestic MCI). Results: A total of 45 studies were included in our meta-analysis. In the MCI group, we found structural atrophy of the bilateral hippocampus, parahippocampal gyrus (PHG), amygdala, right lateral globus pallidus, right insula, and left middle temporal gyrus. The aMCI group exhibited GM atrophy in the bilateral hippocampus, PHG, and amygdala. The naMCI group presented with structural atrophy in the right putamen, right insula, right precentral gyrus, left medial/superior frontal gyrus, and left anterior cingulate. The right lingual gyrus, right cuneus, and left medial frontal gyrus were atrophic GM regions in the SCD group. Conclusion: Our meta-analysis identified unique patterns of neuroanatomical alternations in both the MCI and SCD group. Structural changes in SCD patients provide new evidence for the notion that subtle impairment of visual function, perception, and cognition may be related to early signs of cognitive impairment. In addition, our findings provide a foundation for future targeted interventions at different stages of preclinical Alzheimer’s disease.
Hui Lu, Donglai Jing, Yaojing Chen, Chunlei Cui, Ran Gao, Lin Wang, Zhigang Liang, Kewei Chen, Liyong Wu
Metabolic Changes Detected by 18F-FDG PET in the Preclinical Stage of Familial Creutzfeldt-Jakob Disease
Abstract: Background: Pathologic processes in Creutzfeldt-Jakob disease (CJD) are not fully understood. Familial CJD (fCJD) gives opportunities to discover pathologic changes in the preclinical stage. Objective: To investigate cerebral glucose metabolism in the preclinical stage via 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) in fCJD. Methods: Seven asymptomatic carriers of G114V mutation and six family members without PRNP mutation from the same fCJD kindred were included, and were followed for 2 years. Ten symptomatic CJD patients were also recruited. All subjects underwent standardized clinical examinations and 18F-FDG PET scans. Results were compared in three groups: baseline carriers against non-carriers (baseline analysis), changes after 2 years in carriers (follow-up analysis), and differences between symptomatic CJD patients and healthy controls (CJD patients analysis). Results: No carriers developed any neurological symptoms during 2-year follow-up. Baseline analysis: carriers demonstrates decreased metabolism (p<0.001) in left and right postcentral, left fusiform, left superior temporal, left lingual, left superior parietal, and left Heschl gyrus. Follow-up analysis shows metabolic decline (p<0.001) in right inferior temporal, left supra-marginal and left postcentral lobe, and increased metabolism (p<0.001) in left fusiform, left angular, left thalamus, left Heschl’s, right Rolandic operculum, and left superior parietal gyrus. CJD patients demonstrates decreased metabolism in right inferior triangularis frontal gyrus, right middle occipital gyrus, right putamen, right thalamus, and right middle temporal gyrus. Conclusion: Hypo-metabolism of parietal and temporal lobe can be detected by 18F-FDG PET in the preclinical stage of CJD. Subcortical area might compensate in the preclinical stage and decompensate in the symptomatic stage.
Pilar Pérez-Ros, Rafael Vila-Candel, Salvador Martin-Utrilla, Francisco M. Martínez-Arnau
Health-Related Quality of Life in Community-Dwelling Older People with Cognitive Impairment: EQ-5D-3L Measurement Properties
Abstract: Background: Assessing quality of life (QoL) in older people with cognitive impairment is a challenge. There is no consensus on the best tool, but a short, user-friendly scale is advised. Objective: This study aimed to assess the psychometric properties of the self-reported and generic EQ-5D (including the EQ index and EQ visual analog scale [VAS]) in community-dwelling older adults with cognitive impairment. Methods: Cross-sectional study analyzing the feasibility, acceptability, reliability, and validity of the EQ-5D based on 188 self-administered questionnaires in a sample of community-dwelling older adults with Mini-Mental State Examination (MMSE) scores of 10 to 24 points. Results: The EQ index was 0.69 (± 0.27) and the EQ VAS was 63.8 (± 28.54). Adequate measurement properties were found in acceptability and feasibility. Cronbach's alpha was 0.69. Good validity was observed in the correlation of each dimension of the EQ-5D with geriatric assessment scales. Higher validity was observed for the EQ index compared to the EQ VAS. Conclusion: The EQ-5D scale could be a good tool for assessing health-related QoL in community-dwelling older adults with cognitive impairment, though it is necessary to assess the dimensions and the EQ index.
Eiman Al-Janahi*, Georgios Ponirakis*, Hanadi Al Hamad, Surjith Vattoth, Ahmed Elsotouhy, Ioannis N. Petropoulos, Adnan Khan, Hoda Gad, Mani Chandran, Anoop Sankaranarayanan, Marwan Ramadan, Marwa Elorrabi, Masharig Gadelseed, Rhia Tosino, Priya V. Gawhale, Anjum Arasn, Maryam Alobaidi, Shafi Khan, Pravija Manikoth, Yasmin Hamdi, Susan Osman, Navas Nadukkandiyil, Essa AlSulaiti, Noushad Thodi, Hamad Almuhannadi, Ziyad R. Mahfoud, Ahmed Own, Ashfaq Shuaib, Rayaz A. Malik *These authors contributed equally to this work.
Corneal Nerve and Brain Imaging in Mild Cognitive Impairment and Dementia
Abstract: Background: Visual rating of medial temporal lobe atrophy (MTA) is an accepted structural neuroimaging marker of Alzheimer’s disease. Corneal confocal microscopy (CCM) is a non-invasive ophthalmic technique that detects neuronal loss in peripheral and central neurodegenerative disorders. Objective: To determine the diagnostic accuracy of CCM for mild cognitive impairment (MCI) and dementia compared to medial temporal lobe atrophy (MTA) rating on MRI. Methods: Subjects aged 60-85 with no cognitive impairment (NCI), MCI, and dementia based on the ICD-10 criteria were recruited. Subjects underwent cognitive screening, CCM, and MTA rating on MRI. Results: 182 subjects with NCI (n=36), MCI (n=80), and dementia (n=66), including AD (n=19, 28.8%), VaD (n=13, 19.7%), and mixed AD (n=34, 51.5%) were studied. CCM showed a progressive reduction in corneal nerve fiber density (CNFD, fibers/mm2) (32.0±7.5 versus 24.5±9.6 versus 20.8±9.3, p<0.0001), branch density (CNBD, branches/mm2) (90.9±46.5 versus 59.3±35.7 versus 53.9±38.7, p<0.0001), and fiber length (CNFL, mm/mm2) (22.9±6.1 versus 17.2±6.5 versus 15.8±7.4, p<0.0001) in subjects with MCI and dementia compared to NCI. The area under the ROC curve (95% CI) for the diagnostic accuracy of CNFD, CNBD, CNFL compared to MTA-right and MTA-left for MCI was 78% (67-90%), 82% (72-92%), 86% (77-95%) versus 53% (36-69%) and 40% (25-55%), respectively, and for dementia it was 85% (76-94%), 84% (75-93%), 85% (76-94%) versus 86% (76-96%) and 82% (72-92%), respectively. Conclusion: The diagnostic accuracy of CCM, a non-invasive ophthalmic biomarker of neurodegeneration, was high and comparable with MTA rating for dementia but was superior to MTA rating for MCI.
Michael F. Bergeron, Sara Landset, Xianbo Zhou, Tao Ding, Taghi M. Khoshgoftaar, Feng Zhao, Bo Du, Xinjie Chen, Xuan Wang, Lianmei Zhong, Xiaolei Liu, J. Wesson Ashford (Handling Associate Editor: David Loewenstein)
Utility of MemTrax and Machine Learning Modeling in Classification of Mild Cognitive Impairment
Abstract: Background: The widespread incidence and prevalence of Alzheimer’s disease and mild cognitive impairment (MCI) has prompted an urgent call for research to validate early detection cognitive screening and assessment. Objective: Our primary research aim was to determine if selected MemTrax performance metrics and relevant demographics and health profile characteristics can be effectively utilized in predictive models developed with machine learning to classify cognitive health (normal versus MCI), as would be indicated by the Montreal Cognitive Assessment (MoCA). Methods: We conducted a cross-sectional study on 259 neurology, memory clinic, and internal medicine adult patients recruited from two hospitals in China. Each patient was given the Chinese-language MoCA and self-administered the continuous recognition MemTrax online episodic memory test on the same day. Predictive classification models were built using machine learning with 10-fold cross validation, and model performance was measured using Area Under the Receiver Operating Characteristic Curve (AUC). Models were built using two MemTrax performance metrics (percent correct, response time), along with the eight common demographic and personal history features. Results: Comparing the learners across selected combinations of MoCA scores and thresholds, Naïve Bayes was generally the top-performing learner with an overall classification performance of 0.9093. Further, among the top three learners, MemTrax-based classification performance overall was superior using just the top-ranked four features (0.9119) compared to using all 10 common features (0.8999). Conclusion: MemTrax performance can be effectively utilized in a machine learning classification predictive model screening application for detecting early stage cognitive impairment.
Madeleine M. Blazel, Karen K. Lazar, Carol A. Van Hulle, Yue Ma, Aleshia Cole, Alice Spalitta, Nancy Davenport-Sis, Barbara B. Bendlin, Michelle Wahoske, Chuck Illingworth, Carey E. Gleason, Dorothy F. Edwards, Hanna Blazel, Sanjay Asthana, Sterling C. Johnson, Cynthia M. Carlsson
Factors Associated with Lumbar Puncture Participation in Alzheimer’s Disease Research
Abstract: Background: Cerebrospinal fluid (CSF) provides insight into the spectrum of Alzheimer’s disease (AD) pathology. While lumbar punctures (LPs) for CSF collection are generally considered safe procedures, many participants remain hesitant to participate in research involving LPs. Objective: To explore factors associated with participant willingness to undergo a research LP at baseline and follow-up research study visit. Methods: We analyzed data from 700 participants with varying cognition (unimpaired, mild cognitive impairment, and dementia) in the Wisconsin Alzheimer’s Disease Research Center. We evaluated the relationship of demographic variables (age, sex, race, ethnicity, and years of education) and clinical variables (waist-to-hip ratio, body mass index, AD parental history, cognitive diagnosis) on decision to undergo baseline LP1. We evaluated the relationship of prior LP1 experience (procedure success and adverse events) with the decision to undergo follow-up LP2. The strongest predictors were incorporated into regression models. Results: Over half of eligible participants opted into both baseline and follow-up LP. Participants who underwent LP1 had higher mean education than those who declined (p=0.020). White participants were more likely to choose to undergo LP1 (p<0.001); 33% of African American participants opted in compared to 65% of white participants. Controlling for age, education, and AD parental history, race was the only significant predictor for LP1 participation. Controlling for LP1 mild adverse events, successful LP1 predicted LP2 participation. Conclusion: Race was the most important predictor of baseline LP participation, and successful prior LP was the most important predictor of follow-up LP participation.
David Bergeron, Jean-Mathieu Beauregard, Jean-Guimond, Jean-Paul Soucy, Louis Verret, Stéphane Poulin, Jordi A. Matias-Guiu, María Nieves Cabrera-Martín, Rémi W. Bouchard, Robert Laforce Jr.
Posterior Cingulate Cortex Hypometabolism in Non-Amnestic Variants of Alzheimer’s Disease
Abstract: Background: Hypometabolism of the posterior cingulate cortex (PCC) is an important diagnostic feature of late-onset, amnestic Alzheimer’s disease (AD) measured with 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). However, it is unclear whether PCC hypometabolism has diagnostic value in young-onset, non-amnestic variants of AD, which exhibit less pathology in the hippocampus and default mode network. Objective: Evaluate the prevalence and diagnostic value of PCC hypometabolism in non-amnestic variants of AD. Methods: We retrospectively identified 60 patients with young-onset, atypical dementia who have undergone a detailed clinical evaluation, FDG-PET, and an amyloid biomarker (amyloid-PET or cerebrospinal fluid analysis). We quantitatively analyzed regional hypometabolism in 70 regions of interest (ROI) using the MIMneuro® software. Results: Based on a cut-off of z-score < -1.5 for significant PCC hypometabolism, the prevalence of PCC hypometabolism in non-amnestic variants of AD was 65% compared to 28% in clinical variants of frontotemporal dementia (FTD). The ROI with the maximal hypometabolism was the dominant middle temporal gyrus in the language variant of AD (mean z score -2.28), middle occipital gyrus in PCA (-3.24), middle temporal gyrus in frontal AD (-2.70), and angular gyrus in corticobasal syndrome due to AD (-2.31). The PCC was not among the 10 most discriminant regions between non-amnestic variants of AD versus clinical variants of FTD. Conclusion: We conclude that PCC hypometabolism is not a discriminant feature to distinguish non-amnestic variants of AD from clinical variants of FTD—and should be interpreted with caution in patients with young-onset, non-amnestic dementia.
Shubir Dutt, Yanrong Li, Mara Mather, Daniel A. Nation for the Alzheimer’s Disease Neuroimaging Initiative (Handling Associate Editor: Mark Bondi)
Brainstem Volumetric Integrity in Preclinical and Prodromal Alzheimer’s Disease
Abstract: Background: Neuropathological studies have suggested the tau pathology observed in Alzheimer’s disease (AD) originates in brainstem nuclei, but no studies to date have quantified brainstem volumes in clinical populations with biomarker-confirmed mild cognitive impairment (MCI) or dementia due to AD or determined the value of brainstem volumetrics in predicting dementia. Objective: The present study examined whether MRI-based brainstem volumes differ among cognitively normal older adults and those with MCI or dementia due to AD and whether preclinical brainstem volumes predict future progression to dementia. Methods: Alzheimer’s Disease Neuroimaging Initiative participants (N = 1,629) underwent baseline MRI scanning with variable clinical follow-up (6-120 months). Region of interest and voxel-based morphometric methods assessed brainstem volume differences among cognitively normal (n = 814), MCI (n = 542), and AD (n = 273) participants, as well as subsets of cerebrospinal fluid biomarker-confirmed MCI (n = 203) and AD (n = 160) participants. Results: MCI and AD cases showed smaller midbrain volumes relative to cognitively normal participants when normalizing to whole brainstem volume, and showed smaller midbrain, locus coeruleus, pons, and whole brainstem volumes when normalizing to total intracranial volume. Cognitively normal individuals who later progressed to AD dementia diagnosis exhibited smaller baseline midbrain volumes than individuals who did not develop dementia, and voxel-wise analyses revealed specific volumetric reduction of the locus coeruleus. Conclusion: Findings are consistent with neuropathological observations of early AD-related pathology in brainstem nuclei and further suggest the clinical relevance of brainstem substructural volumes in preclinical and prodromal AD.
Yi Ling, Qilu Gu, Junmei Zhang, Tianyu Gong, Xiongpeng Weng, Jiaming Liu, Jing Sun (Handling Associate Editor: Claire Roubaud Baudron)
Structural Change of Gut Microbiota in Patients with Post-Stroke Comorbid Cognitive Impairment and Depression and Its Correlation with Clinical Features
Abstract: Background: Post-stroke comorbid cognitive impairment and depression (PSCCID) is a severe neuropsychiatric complication after acute stroke. Gut microbiota dysbiosis is associated with many psychiatric disorders. Alterations in the composition of gut microbiota may serve as a critical role in patients with PSCCID. Objective: We aimed to characterize the microbial profiles of patients with PSCCID. Method: A total of 175 stroke patients were recruited in the study. The composition of gut bacterial communities of patients was determined by 16S ribosomal RNA Miseq sequencing, and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States was used to demonstrate the functional alterations of gut microbiota. We further identified the characteristic gut microbiota of PSCCID using linear discriminant analysis effect size. Results: Patients with PSCCID exhibited an increased abundance of Proteobacteria, including Gammaproteobacteria, Enterobacteriales, and Enterobacteriaceae, and a decreased abundance of several short-chain fatty acids-producing bacteria compared with non-PSCCID patients. The abundance of Gammaproteobacteria and Enterobacteriaceae showed negative correlations with the MoCA score. Moreover, the Kyoto Encyclopedia of Genes and Genomes results demonstrated the enriched orthologs of glycan biosynthesis and metabolism and decreased orthologs of amino acid metabolism in PSCCID patients. Importantly, the characteristic gut microbiota was identified and achieved an area under the curve of 0.847 between the two groups. Conclusion: In this study, we characterized the gut microbiota of PSCCID patients, and revealed the correlations of the altered gut microbiota with clinical parameters, which took a further step towards non-invasive diagnostic biomarkers for PSCCID from fecal samples.
Franziska Mathies, Catharina Lange, Anja Mäurer, Ivayla Apostolova, Susanne Klutmann, Ralph Buchert (Handling Associate Editor: Flavio Nobili)
Brain FDG PET for the Etiological Diagnosis of Clinically Uncertain Cognitive Impairment During Delirium in Remission
Abstract: Background: Positron emission tomography (PET) of the brain with 2-[F-18]-fluoro-2-deoxy-D-glucose (FDG) is widely used for the etiological diagnosis of clinically uncertain cognitive impairment (CUCI). Acute full-blown delirium can cause reversible alterations of FDG uptake that mimic neurodegenerative disease. Objective: This study tested whether delirium in remission affects the performance of FDG PET for differentiation between neurodegenerative and non-neurodegenerative etiology of CUCI. Methods: The study included 88 patients (82.0±5.7 y) with newly detected CUCI during hospitalization in a geriatric unit. Twenty-seven (31%) of the patients were diagnosed with delirium during their current hospital stay, which, however, at time of enrollment was in remission so that delirium was not considered the primary cause of the CUCI. Cases were categorized as neurodegenerative or non-neurodegenerative etiology based on visual inspection of FDG PET. The diagnosis at clinical follow-up after ≥12 months served as ground truth to evaluate the diagnostic performance of FDG PET. Results: FDG PET was categorized as neurodegenerative in 51 (58%) of the patients. Follow-up after 16±3 months was obtained in 68 (77%) of the patients. The clinical follow-up diagnosis confirmed the FDG PET-based categorization in 60 patients (88%, 4 false negative and 4 false positive cases with respect to detection of neurodegeneration). The fraction of correct PET-based categorization did not differ between patients with delirium in remission and patients without delirium (86% versus 89%, p=0.666). Conclusion: Brain FDG PET is useful for the etiological diagnosis of CUCI in hospitalized geriatric patients, as well as in patients with delirium in remission.
Adam O. Ghoweri, Peter Gagolewicz, Hilaree N. Frazier, John C. Gant, R. David Andrew, Brian M. Bennett, Olivier Thibault (Handling Associate Editor: Sergio Ferreira)
Neuronal Calcium Imaging, Excitability, and Plasticity Changes in the Aldh2-/- Mouse Model of Sporadic Alzheimer's Disease
Abstract: Background: Dysregulated signaling in neurons and astrocytes participates in pathophysiological alterations seen in the Alzheimer’s disease brain, including increases in amyloid-β, hyperphosphorylated tau, inflammation, calcium dysregulation, and oxidative stress. These are often noted prior to the development of behavioral, cognitive, and non-cognitive deficits. However, the extent to which these pathological changes function together or independently is unclear. Objective: Little is known about the temporal relationship between calcium dysregulation and oxidative stress, as some reports suggest that dysregulated calcium promotes increased formation of reactive oxygen species, while others support the opposite. Prior work has quantified several key outcome measures associated with oxidative stress in aldehyde dehydrogenase 2 knockout (Aldh2-/-) mice, a non-transgenic model of sporadic Alzheimer’s disease. Methods: Here, we tested the hypothesis that early oxidative stress can promote calcium dysregulation across aging by measuring calcium-dependent processes using electrophysiological and imaging methods and focusing on the afterhyperpolarization (AHP), synaptic activation, somatic calcium, and long-term potentiation in the Aldh2-/- mouse. Results: Our results show a significant age-related decrease in the AHP along with an increase in the slow AHP amplitude in Aldh2-/- animals. Measures of synaptic excitability were unaltered, although significant reductions in long-term potentiation maintenance were noted in the Aldh2-/- animals compared to wild-type. Conclusion: With so few changes in calcium and calcium-dependent processes in an animal model that shows significant increases in HNE adducts, Aβ, p-tau, and activated caspases across age, the current findings do not support a direct link between neuronal calcium dysregulation and uncontrolled oxidative stress.
Ge Song, Haiqiang Yang, Ning Shen, Phillip Pham, Breanna Brown, Xiaoyang Lin, Yuzhu Hong, Paul Sinu, Jianfeng Cai, Xiaopeng Li, Michael Leon, Marcia Gordon, David Morgan, Sai Zhang, Chuanhai Cao
An Immunomodulatory Therapeutic Vaccine Targeting Oligomeric Amyloid-β
Abstract: Background: Aging is considered the most important risk factor for Alzheimer’s disease (AD). Recent research supports the theory that immunotherapy targeting the “oligomeric” forms of amyloid-β (Aβ) may halt the progression of AD. However, previous clinical trial of the vaccine against Aβ, called AN1792, was suspended due to cases of meningoencephalitis in patients. Objective: To develop a peptide sensitized dendritic cells (DCs) vaccine that would target oligomer Aβ and prevent an autoimmune response. Methods: Double transgenic APPswe/PS1ΔE9 (Tg) and C57BL/6J control mice were used in this study. Cytokine expression profile detection, characterization of antisera, brain GSK-3β, LC3 expression, and spatial working memory testing before and post-vaccination were obtained. Results: Epitope prediction indicated that E22W42 could generate 13 new T cell epitopes which can strengthen immunity in aged subjects and silence several T cell epitopes of the wild type Aβ. The silenced T cell epitope could help avoid the autoimmune response that was seen in some patients of the AN-1792 vaccine. The E22W42 not only helped sensitize bone marrow-derived DCs for the development of an oligomeric Aβ-specific antibody, but also delayed memory impairment in the APP/PS1 mouse model. Most importantly, this E22W42 peptide will not alter the DC’s natural immunomodulatory properties. Conclusion: The E22W42 vaccine is possibly safer for patients with impaired immune systems. Since there is increasing evidence that oligomeric form of Aβ are the toxic species to neurons, the E22W42 antibody’s specificity for these “oligomeric” Aβ species could provide the opportunity to produce some clinical benefits in AD subjects.
Isabel J. Sible, Daniel A. Nation for the Alzheimer’s Disease Neuroimaging Initiative (Handling Associate Editor: Whitney Wharton)
Long-Term Blood Pressure Variability Across the Clinical and Biomarker Spectrum of Alzheimer’s Disease
Abstract: Background: Elevated blood pressure is linked to cognitive impairment and Alzheimer’s disease (AD) biomarker abnormality. However, blood pressure levels vary over time. Less is known about the role of long-term blood pressure variability in cognitive impairment and AD pathophysiology. Objective: Determine whether long-term blood pressure variability is elevated across the clinical and biomarker spectrum of AD. Methods: Alzheimer’s Disease Neuroimaging Initiative participants (cognitively normal, mild cognitive impairment, AD [n=1,421]) underwent baseline exam, including blood pressure measurement at 0, 6, and 12 months. A subset (n=318) underwent baseline lumbar puncture to determine cerebrospinal fluid amyloid-β and phosphorylated tau levels. Clinical groups and biomarker-confirmed AD groups were compared on blood pressure variability over 12 months. Results: Systolic blood pressure variability was elevated in clinically diagnosed AD dementia (VIM: F2,1195 = 6.657, p = 0.001, η2 = 0.01) compared to cognitively normal participants (p = 0.001), and in mild cognitive impairment relative to cognitively normal participants (p = 0.01). Findings were maintained in biomarker-confirmed AD (VIM: F2,850 = 5.216, p = 0.006, η2 = 0.01), such that systolic blood pressure variability was elevated in biomarker-confirmed dementia due to AD relative to cognitively normal participants (p = 0.005) and in biomarker-confirmed mild cognitive impairment due to AD compared to cognitively normal participants (p = 0.04). Conclusion: Long-term systolic blood pressure variability is elevated in cognitive impairment due to AD. Blood pressure variability may represent an understudied aspect of vascular dysfunction in AD with potential clinical implications.
Fan He, James J. Tang, Tao Zhang, Junfen Lin, Fudong Li, Xue Gu, Ruoling Chen
Impact of Air Pollution on Cognitive Impairment in Older People: A Cohort Study in Rural and Suburban China
Abstract: Background: The impact of air pollution on cognitive impairment in older people has not been fully understood. It is unclear which air pollutants are the culprit. Objective: We assessed the associations of six air pollutants and air quality index (AQI) with cognitive impairment. Methods: We examined 7,311 participants aged ≥60 years from the ZJMPHS cohort in China. They were interviewed for baseline socio-demographic and disease risk factors in 2014, and re-interviewed in 2015 and 2016, respectively. The presence of cognitive impairment was determined by the Chinese version of the Mini-Mental State Examination. Daily area-level data monitored for air pollution during 2013-2015 was then examined for associations with cognitive impairment in logistic regression models. Results: Over the two years follow-up, 1,652 participants developed cognitive impairment, of which 917 were severe cases. Continuous air pollution data showed the risk of cognitive impairment increased with exposure to PM2.5 (fully adjusted odds ratio [aOR] 1.04, 95%CI 1.01-1.08), PM10 (1.03, 1.001-1.06), and SO2 (1.04, 1.01-1.08), but not with NO2, CO, O3, and AQI. Categorized data analysis for low, middle, and high level exposure demonstrated that the aOR increased with PM2.5 and AQI, somehow with PM10 and CO, but not significantly with SO2 and NO2, and decreased with O3. The patterns for these associations with severe cognitive impairment were stronger. Conclusion: Lowering PM2.5, PM10, SO2, and CO level could reduce the risk of cognitive impairment in older Chinese. Strategies to target most important air pollutants should be an integral component of cognitive interventions.
Soohyun Chae, Jinsick Park, Min Soo Byun, Dahyun Yi, Jun Ho Lee, Gi Hwan Byeon, Hye Won Suk, Hongyoon Choi, Jee Eun Park, Dong Young Lee
Decreased Alpha Reactivity from Eyes-Closed to Eyes-Open in Non-Demented Older Adults with Alzheimer’s Disease: A Combined EEG and [18F]florbetaben PET Study
Abstract: Background: The degree of alpha attenuation from eyes-closed (EC) to eyes-open (EO) has been suggested as a neural marker of cognitive health, and its disruption has been reported in patients with clinically defined Alzheimer’s disease (AD) dementia. Objective: We tested if EC-to-EO alpha reactivity was related to cerebral amyloid-β (Aβ) deposition during the early stage of AD. Methods: Non-demented participants aged ≥55 years who visited the memory clinic between March 2018 and June 2019 (N = 143; 67.8% female; mean age ± standard deviation, 74.0 ± 7.6 years) were included in the analyses. Based on the [18F]florbetaben positron emission tomography assessment, the participants were divided into Aβ+ (N = 70) and Aβ- (N = 73) groups. EEG was recorded during the 7-min EC condition followed by a 3-min EO phase, and a Fourier transform spectral analysis was performed. Results: A significant three-way interaction was detected among Aβ positivity, eye condition, and the laterality factor on alpha-band power after adjusting for age, sex, educational years, global cognition, depression, medication use, and white matter hyperintensities on magnetic resonance imaging (F = 5.987, p = 0.016); EC-to-EO alpha reactivity in the left hemisphere was significantly reduced in Aβ+ subjects without dementia compared with the others (F = 3.984, p = 0.048). Conclusion: Among mild cognitive impairment subjects, alpha reactivity additively contributed to predict cerebral Aβ positivity beyond the clinical predictors, including vascular risks, impaired memory function, and apolipoprotein E ε4. These findings support that EC-to-EO alpha reactivity acts as an early biomarker of cerebral Aβ deposition and is a useful measurement for screening early-stage AD.
Nathalie R. de Vent, Joost A. Agelink van Rentergem, Hilde M. Huizenga, Wiesje M. van der Flier, Sieske A.M. Sikkes, Jaap M.J. Murre, Karlijn A. van den Bosch, Philip Scheltens, Ben A. Schmand
An Operational Definition of ‘Abnormal Cognition’ to Optimize the Prediction of Progression to Dementia: What Are Optimal Cut-Off Points for Univariate and Multivariate Normative Comparisons?
Abstract: Background: In neuropsychology and neurology, there is no consensus on the definition of abnormal cognition. Objective: To operationally define ‘abnormal cognition’ for optimally predicting progression to dementia in a memory clinic sample, and to test whether multivariate profile analysis of cognitive test results improves this prediction compared to standard clinical evaluation. Methods: We used longitudinal data from 835 non-demented patients of the Amsterdam Dementia Cohort. For 10 cognitive measures at baseline, we determined which number of abnormal tests and which magnitude of score deviations best predicted progression. Results: Predictive ability for progression to dementia of one, two, and three abnormal test scores out of 10 is highly similar (Cox hazard ratios: 3.7–4.1) provided cut-off values are adapted appropriately. Cut-offs have to be less stringent if the number of abnormal tests required increases: the optimal cut-off is z < -1.45 when one deviating score is required, z < -1.15 when two abnormal tests are required, and z < -0.70 when three abnormal tests are required. The profile analysis has similar predictive ability at the cut-off of p < 0.22 (hazard ratio 3.8). A likelihood ratio test showed that this analysis improves prediction of progression to dementia when added to standard clinical evaluation (p<0.001). Conclusion: Abnormal cognition may be defined as one, two, or three abnormal test scores out of 10 if the magnitude of score deviations is adapted accordingly. An abnormal score profile predicts decline to dementia equally well, and improves the prediction when used complimentary to standard clinical evaluation.
Leah C. Beauchamp, Xiang M. Liu, Amelia Sedjahtera, Mirjana Bogeski, Laura J. Vella, Ashley I. Bush, Paul A. Adlard, Kevin J. Barnham
S-Adenosylmethionine Rescues Cognitive Deficits in the rTg4510 Animal Model by Stabilizing Protein Phosphatase 2A and Reducing Phosphorylated Tau
Abstract: Background: Alterations in the methionine cycle and abnormal tau phosphorylation are implicated in many neurodegenerative diseases, including Alzheimer’s disease and frontotemporal dementia. rTg4510 mice express mutant human P301L tau and are a model of tau hyperphosphorylation. The cognitive deficit seen in these animals correlates with a burden of hyperphosphorylated tau and is a model to test therapies aimed at lowering phosphorylated tau. Objective: This study aimed to increase protein phosphatase 2A activity through supplementation of S-adenosylmethionine and analyze the effect on spatial memory and tau in treated animals. Methods: 6-month-old rTg4510 mice were treated with 100 mg/kg S adenosylmethionine by oral gavage for 3 weeks. Spatial recognition memory was tested in the Y-maze. Alterations to phosphorylated tau and protein phosphatase 2A were explored using immunohistochemistry, western blot, and enzyme-linked immunosorbent assays. Results: Treatment with S-adenosylmethionine increased the Y-maze novel arm exploration time and increased both the expression and activity of protein phosphatase 2A. Furthermore, treatment reduced the number of AT8 positive neurons and reduced the expression of phosphorylated tau (Ser202/Thr205). S-adenosylmethionine contributes to multiple pathways in neuronal homeostasis and neurodegeneration. Conclusion: This study shows that supplementation with S-adenosylmethionine stabilizes the heterotrimeric form of PP2A resulting in an increase the enzymatic activity, a reduced level of pathological tau, and improved cognition.
MingRui Dai, XueJian Feng, ZengShuo Mo, Yao Sun, Lu Fu, Yong Zhang, Jiaxin Wu, Bin Yu, Haihong Zhang, Xianghui Yu, Hui Wu, Wei Kong
Stimulation Effects and Mechanisms of Different Adjuvants on a Norovirus P Particle-Based Active Amyloid-β Vaccine
Abstract: Background: Adjuvants are important components of vaccines and effectively enhance the immune response of specific antigens. However, the role of adjuvants or combinations of adjuvants in stimulating immunogenicity of the amyloid-β (Aβ) vaccine, as well as molecular mechanisms underlying such stimulation still remain unclear. A previous study of ours developed a norovirus P particle-based active Aβ epitope vaccine, PP-3copy-Aβ1-6-loop123, which stimulates a high titer of Aβ-specific antibodies in mouse Alzheimer’s disease (AD) models. Objective: The most effective and safe adjuvant that maximizes the immunogenicity of our protein vaccine was determined. Methods: We investigated four adjuvants (CpG, AS02, AS03, and MF59), and combinations of those, for capacity to enhance immunogenicity, and performed transcriptome analysis to explore mechanisms underlying the role of these in AD immunotherapy. Results: Addition of the adjuvant, AS02, remarkably improved the immunogenicity of the PP-3copy-Aβ1-6-loop123 vaccine without triggering an Aβ-specific T-cell response. Combinations of adjuvants, particularly CpG+AS02 and CpG+AS03, elicited a significantly elevated and prolonged Aβ-specific antibody response. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses indicated that a combination of two adjuvants was more effective in activating immune-related pathways, thereby enhancing the immunogenicity of PP-3copy-Aβ1-6-loop123. Conclusion: These findings demonstrated that adjuvants can be used as enhancers in AD protein vaccination, and that a combination of CpG and AS-related adjuvants may be a very effective adjuvant candidate suitable for further clinical trials of the PP-3copy-Aβ1-6-loop123 vaccine. Our studies also revealed potential mechanisms underlying the stimulation of immune response of protein vaccines by adjuvants.
Yosuke Osuka, Narumi Kojima, Hiroyuki Sasai, Yuki Ohara, Yutaka Watanabe, Hirohiko Hirano, Hunkyung Kim
Exercise Types and the Risk of Developing Cognitive Decline in Older Women: A Prospective Study
Abstract: Background: Participation in exercise may be useful for dementia prevention; however, the specific exercise types which may best to reduce the risk of developing cognitive decline have remained unidentified in the literature. Objective: To examine the relationships of specific exercise types with the risk of developing cognitive decline in older women. Methods: This 1- to 2-year population-based cohort study included 687 community-dwelling older Japanese women without disability, neurological disease, dementia, or cognitive impairment assessed as < 24 points on the Mini-Mental State Examination (MMSE) at the baseline survey. Developing cognitive decline was defined as a decrease of ≥ 3 points in the participant’s MMSE score during the follow-up. We classified individuals into participation (≥3 months) and non-participation (< 3 months) groups for 17 different exercise types. Log-binominal regression analyses were applied to compare risk ratios and confidence intervals of developing cognitive decline between the two groups. Results: Thirty-nine participants (5.7%) developed cognitive decline during the follow-up period. After adjusting for confounders (age, MMSE score, depressive symptoms, body mass index, heart disease, hypertension, diabetes, smoking, low educational level, and the follow-up period in the baseline survey), those who participated in calisthenics demonstrated a significantly lower risk of developing cognitive decline than those who did not participate in calisthenics. No significant relationships between other exercise types and the risk of developing cognitive decline were found. Conclusion: Participation in calisthenics significantly reduced the risk of cognitive decline in community-dwelling older Japanese women, indicating that calisthenics may be a useful type of exercise for promoting dementia prevention.
Clara Vila-Castelar, Edmarie Guzmán-Vélez, Enmanuelle Pardilla-Delgado, Rachel Buckley, Yamile Bocanegra, Ana Baena, Joshua T. Fox-Fuller Victoria Tirado, Claudia Munoz, Margarita Giraldo, Natalia Acosta-Baena, Silvia Rios-Romenets, Jessica B. Langbaum, Pierre N. Tariot, Francisco Lopera, Eric M. Reiman, Yakeel T. Quiroz (Handling Associate Editor: Jessica Kirkland Caldwell)
Examining Sex Differences in Markers of Cognition and Neurodegeneration in Autosomal Dominant Alzheimer’s Disease: Preliminary Findings from the Colombian Alzheimer’s Prevention Initiative Biomarker Study
Abstract: Background: Growing evidence suggests that there may be a sex-specific biological risk for Alzheimer’s disease (AD). Individuals with autosomal dominant AD due to a mutation (E280A) in Presenilin-1 (PSEN1) are genetically determined to develop early-onset dementia and thus, have few age-related risk factors for AD that are known to vary by sex (i.e., cardiovascular disease, menopause, life expectancy). Objective: Investigate sex differences in markers of cognition and neurodegeneration in autosomal dominant AD. Methods: We conducted a retrospective study in 19 cognitively-unimpaired PSEN1 mutation carriers (age range 20-44; 11 females), 11 symptomatic carriers (age range 42-56; 8 females), and 23 matched non-carriers family members (age range 20-50; 13 females). We examined hippocampal volume ratio, CERAD Total Score, and CERAD Word List (i.e., Learning, Delayed Recall, and Recognition). Mann-Whitney U tests, Spearman correlations and regression models were conducted. Results: There were no differential associations between age, CERAD Total Score, CERAD Word List–Learning, Delayed Recall, Recognition, and hippocampal volume ratio in male and female carriers and non-carriers. Cognitively-unimpaired female carriers showed better CERAD Total scores and CERAD Word List–Learning than cognitively-unimpaired male carriers, despite having similar hippocampal volume ratios. The interaction of sex and hippocampal volume ratio did not predict cognitive performance across groups. Conclusion: Our preliminary findings suggest that cognitively-unimpaired female carriers showed a verbal memory reserve, while, as disease progresses, female carriers did not exhibit a cognitive susceptibility to AD-related neurodegeneration. Future studies with larger samples of autosomal dominant AD are warranted to further understand sex differences in AD-related clinical and pathological markers.
Francesca Pisano, Carlo Caltagirone, Federica Satriano, Roberta Perri, Lucia Fadda, Paola Marangolo (Handling Associate Editor: Claudio Babiloni)
Can Alzheimer’s Disease Be Prevented? First Evidence from Spinal Stimulation Efficacy on Executive Functions
Abstract: Background: Recently, a growing body of evidence has shown that, from the early stage of impairment, Alzheimer’s patients (AD) present difficulties on a variety of tasks mostly relying on executive functions. These strongly impact their daily life activities causing a severe loss of independency and autonomy. Objective: To evaluate the efficacy of transpinal direct current stimulation (tsDCS) combined with cognitive trainings for improving attentional and executive function abilities in a group of AD patients. Methods: In a randomized-double blind design, sixteen AD patients underwent different cognitive trainings combined with tsDCS. During the treatment, each subject received tsDCS (20 min, 2 mA) over the thoracic vertebrae (IX-X vertebrae) in two different conditions: 1) anodal, and 2) sham while performing three computerized tasks: alertness, selective attention, and executive functions. Each experimental condition was run in ten consecutive daily sessions over two weeks. Results: After anodal tsDCS, a greater improvement in executive functions compared to sham condition was found. More importantly, the follow-up testing revealed that these effects lasted over 1 month after the intervention and generalized to the different neuropsychological tests administered before, after the treatment and at one month after the end of the intervention. This generalization was present also in the attentional domain. Conclusion: This evidence emphasizes, for the ﬁrst time, that tsDCS combined with cognitive training results efficacious for AD patients. We hypothesize that enhancing activity into the spinal sensorimotor pathways through stimulation improved cognitive abilities which rely on premotor activity, such as attention and executive functions.
Olivia G. Holloway, Anna E. King, Jenna M. Ziebell (Handling Associate Editor: Zhou Wu)
Microglia Demonstrate Local Mixed Inflammation and a Defined Morphological Shift in an APP/PS1 Mouse Model
Abstract: Background: Microglia are traditionally described as the immune cells of the brain and have an inflammatory role in Alzheimer’s disease (AD). Microglial morphological and phenotypic shifts in AD have not been fully characterized; however, microglia are often described as either pro- or anti-inflammatory. Objective: To determine microglial if microglial morphology and phenotype changes with disease status. Methods: This study observed morphology through Iba1 immunohistochemistry on tissue sections encompassing the primary motor cortex and somatosensory barrel fields. Immunohistochemistry for pro-inflammatory markers: CD14 and CD40; and anti-inflammatory markers: CD16 and TREM2, was performed at 3, 6, and 12 months of age which correlated with pre-plaque, onset, and significant plaque load in APP/PS1 brains (n=6) and compared to age-matched littermate controls (n = 6). Results: Microglia demonstrated a defined morphological shift with time. Deramified morphologies increased in the APP/PS1, at both 6 months (p < 0.0001) and 12 months (p < 0.0001). At 12 months, there were significantly lower numbers of ramified microglia (p < 0.001). Results indicated that microglia have a heterogenic marker immunoreactivity as CD16, TREM2, and CD40 were associated with an activated morphology at the same time points. All inflammatory markers were significantly upregulated at 12 months in the APP/PS1 mice (TREM2 (F(2, 30) = 10.75, p = 0.0003), CD40 (F(2, 30) = 15.86, p < 0.0001), CD14 (F(2, 30) = 6.84, p = 0.0036), and CD16 (F(2, 30) = 3.026, p = 0.0635)). Conclusion: Our data indicate that pro- and anti-inflammatory factors of microglia occur in APP/PS1 mice.
Bethany Hulme, Altug Didikoglu, Steven Bradburn, Andrew Robinson, Maria Canal, Antony Payton, Neil Pendleton, Chris Murgatroyd
Epigenetic Regulation of BMAL1 with Sleep Disturbances and Alzheimer’s Disease
Abstract: Background: An early symptom of Alzheimer’s disease (AD) is a disturbance of the circadian rhythm that is associated with disrupted sleep/wake cycles. Objective: To investigate if BMAL1, a key gene that drives the circadian cycle, is epigenetically regulated in brains in relation to longitudinal changes in cognition, sleep quality, and AD neuropathology. Methods: Frontal cortex tissues were acquired from the Manchester Brain Bank (N = 96). DNA methylation at six CpG sites at the promoter of BMAL1, determined using bisulfite pyrosequencing, was tested for associations with Braak stage, CERAD score, and Thal phase, longitudinal changes in cognition, sleep measurements, and cross-section measures of depressive symptoms (BDI score). Results: Methylation across all the CpGs strongly correlated with each other. We found increased CpG2 methylation with higher Braak (t(92)=2.47, p=0.015) and CERAD (t(94 )=2.04, p=0.044) stages. No significance was found between longitudinal fluid intelligence, processing speed, and memory tests, but methylation at CpG1 (r=0.20, p=0.05) and CpG4 (r=0.20, p=0.05) positively correlated with vocabulary. CpG2 positively correlated with cross-sectional fluid intelligence (r=0.20 p=0.05) and vocabulary (r=0.22 p=0.03). Though longitudinal analysis revealed no significance between sleep duration, midsleep, and efficiency for any of the CpG sites, CpG3 (B=0.03, 95%CI=0.00/0.06, p=0.03) and CpG5 (B=0.04, 95%CI=0.01,0.07, p=0.01) significantly correlated with night wake. CpG4 correlated with depressive symptoms (B=-0.27, 95%CI=0.49/-0.05, p=0.02). Conclusion: Methylation of BMAL1 associated with tau pathology, changes in cognitive measures, a measure of sleep and depressive symptoms, suggesting an involvement of the circadian cycle.
Patrick J. Smith, Stephanie M. Mabe, Andrew Sherwood, P. Murali Doraiswamy, Kathleen A. Welsh-Bohmer, James R. Burke, William E. Kraus, Pao-Hwa Lin, Jeffrey N. Browndyke, Michael A. Babyak, Alan L. Hinderliter, James A. Blumenthal
Metabolic and Neurocognitive Changes Following Lifestyle Modification: Examination of Biomarkers from the ENLIGHTEN Randomized Clinical Trial
Abstract: Background: Previous studies have demonstrated that aerobic exercise (AE) and the Dietary Approaches to Stop Hypertension (DASH) diet can improve neurocognition. However, the mechanisms by which lifestyle improves neurocognition have not been widely studied. We examined the associations between changes in metabolic, neurotrophic, and inflammatory biomarkers with executive functioning among participants from the Exercise and Nutritional Interventions for Neurocognitive Health Enhancement (ENLIGHTEN) trial. Objective: To examine the association between changes in metabolic function and neurocognition among older adults with cognitive impairment, but without dementia (CIND) participating in a comprehensive lifestyle intervention. Methods: ENLIGHTEN participants were randomized using a 2 X 2 factorial design to receive AE, DASH, both AE+DASH, or a health education control condition (HE) for six months. Metabolic biomarkers included insulin resistance (homeostatic model assessment [HOMA-IR]), leptin, and insulin-like growth factor (IGF-1); neurotrophic biomarkers included brain derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF); and inflammatory biomarkers included interleukin-6 (IL-6) and C-Reactive Protein (CRP). Results: Participants included 132 sedentary older adults (mean age = 65 [SD = 7]) with CIND. Results demonstrated that both AE (d = 0.48, p = 0.015) and DASH improved metabolic function (d = 0.37, p = 0.039), without comparable improvements in neurotrophic or inflammatory biomarkers. Greater improvements in metabolic function, including reduced HOMA-IR (B = -2.3 [-4.3, -0.2], p = 0.033) and increased IGF-1 (B = 3.4 [1.2, 5.7], p = 0.004), associated with increases in Executive Function. Conclusion: Changes in neurocognition after lifestyle modification are associated with improved metabolic function.
Carla Abdelnour*, Ester Esteban de Antonio*, Alba Pérez-Cordón, Asunción Lafuente, Mar Buendía, Ana Pancho, Sara Jofresa, Nuria Aguilera, Marta Ibarria, Rosario Cuevas, Laia Cañada, Anna Calvet, Susana Diego, Antonio González-Pérez, Adela Orellana, Laura Montrreal, Laura de Jorge, Marta Marquié, Alba Benaque, Miren Gurruchaga, Lluís Tárraga, Agustín Ruiz, Mercè Boada, for the Research Center and Memory Clinic, Fundació ACE *These authors contributed equally to this work.
Managing Clinical Trials for Alzheimer’s Disease During the COVID-19 Crisis: Experience at Fundació ACE in Barcelona, Spain
Abstract: Background: The COVID-19 pandemic has brought great disruption to health systems worldwide. This affected ongoing clinical research, particularly among those most vulnerable to the pandemic, like dementia patients. Fundació ACE is a research center and memory clinic based in Barcelona, Spain, one of the hardest-hit countries. Objective: To describe the ad-hoc strategic plan developed to cope with this crisis and to share its outcomes. Methods: We describe participants’ clinical and demographic features. Additionally, we explain our strategic plan aimed at minimizing the impact on clinical trial research activities, which included SARS-CoV-2 RT-PCR and IgG serological tests to all participants and personnel. The outcomes of the plan are described in terms of observed safety events and drop-outs during the study period. Results: A total of 130 patients were participating in 16 active clinical trials in Fundació ACE when the lockdown was established. During the confinement, we performed 1018 calls to the participants, which led to identify adverse events in 26 and COVID-19 symptoms in 6. A total of 83 patients (64%) could restart on-site visits as early as May 11, 2020. All SARS-CoV-2 RT-PCR diagnostic tests performed before on-site visits were negative and only three IgG serological tests were positive. Throughout the study period, we only observed one drop-out, due to an adverse event unrelated to COVID-19. Discussion: The plan implemented by Fundació ACE was able to preserve safety and integrity of ongoing clinical trials. We must use the lessons learned from the pandemic and design crisis-proof protocols for clinical trials.