Ragnhild E. Skogseth*, Tibor Hortobágyi*, Hogne Soennesyn, Luiza Chwiszczuk, Dominic ffytche, Arvid Rongve, Clive Ballard, Dag Aarsland (Handling Associate Editor: Irina Alafuzoff) *These authors contributed equally to this work.
Accuracy of Clinical Diagnosis of Dementia with Lewy Bodies versus Neuropathology
Abstract: Background: The first consensus criteria for dementia with Lewy bodies (DLB) published in 1996 were revised in 2005, partly because the original clinical criteria had suboptimal sensitivity. Few studies have assessed the accuracy of the 2005 criteria applied prospectively in newly diagnosed patients who have been followed longitudinally. Objective: To explore the correlation between clinical and pathological diagnoses in patients with DLB and Parkinson’s disease with dementia (PDD). Methods: From a prospective referral cohort study with enriched recruitment of patients with DLB and PDD, we included the first 56 patients coming to autopsy. Patients had mild dementia at inclusion and were followed annually until death with standardized clinical assessments. Pathological assessment was performed blind to clinical information according to standardized protocols and consensus criteria for DLB. Results: 20 patients received a pathological diagnosis of Lewy body disease; the corresponding clinical diagnoses were probable DLB (n=11), PDD (n=5), probable (n=2) or possible (n=2) Alzheimer’s disease (AD). Of 14 patients with a clinical diagnosis of probable DLB, 11 had DLB/PDD and 3 had AD at pathology. One patient with clinically possible DLB fulfilled criteria for pathological AD. Sensitivity, specificity, positive predictive value, and negative predictive values for probable DLB were 73%, 93%, 79%, and 90%. Conclusion: Our findings suggest that the international clinical consensus criteria for DLB perform reasonably well. However, false positive and false negative diagnoses still occur, indicating that the criteria need to be improved, that biomarkers may be needed, and that neuropathological feedback is vital to improve accuracy.
Anandhi Iyappan, Erfan Younesi, Alberto Redolfi, Henri Vrooman, Shashank Khanna, Giovanni B. Frisoni, Martin Hofmann-Apitius, for the Alzheimer's Disease Neuroimaging Initiative
Neuroimaging Feature Terminology: A Controlled Terminology for the Annotation of Brain Imaging Features
Abstract: Ontologies and terminologies are used for interoperability of knowledge and data in a standard manner among interdisciplinary research groups. Existing imaging ontologies capture general aspects of the imaging domain as a whole such as methodological concepts or calibrations of imaging instruments. However, none of the existing ontologies covers the diagnostic features measured by imaging technologies in the context of neurodegenerative diseases. Therefore, the Neuro-Imaging Feature Terminology (NIFT) was developed to organize the knowledge domain of measured brain features in association with neurodegenerative diseases by imaging technologies. The purpose is to identify quantitative imaging biomarkers that can be extracted from multi-modal brain imaging data. This terminology attempts to cover measured features and parameters in brain scans relevant to disease progression. In this paper, we demonstrate the systematic retrieval of measured indices from literature and how the extracted knowledge can be further used for disease modeling that integrates neuroimaging features with molecular processes.
Maya De Belder, Patrick Santens, Anne Sieben, Wim Fias (Handling Associate Editor: David Libon)
Impaired Processing of Serial Order Determines Working Memory Impairments in Alzheimer’s Disease
Abstract: Background: Working memory (WM) problems are commonly observed in Alzheimer’s disease (AD), but the affected mechanisms leading to impaired WM are still insufficiently understood. The ability to efficiently process serial order in WM has been demonstrated to be fundamental to fluent daily life functioning. The decreased capability to mentally process serial position in WM has been put forward as the underlying explanation for generally compromised WM performance. Objective: Determine which mechanisms, such as order processing, are responsible for deficient WM functioning in AD. Method: A group of AD patients (n = 32) and their partners (n = 25), assigned to the control group, were submitted to an extensive battery of neuropsychological and experimental tasks, assessing general cognitive state and functioning of several aspects related to serial order WM. Results: The results revealed an impaired ability to bind item information to serial position within WM in AD patients compared to controls. It was additionally observed that AD patients experienced specific difficulties with directing spatial attention when searching for item information stored in WM. Conclusion: The processing of serial order and the allocation of attentional resources are both disrupted, explaining the generally reduced WM functioning in AD patients. Further studies should now clarify whether this observation could explain disease-related problems for other cognitive functions such as verbal expression, auditory comprehension, or planning.
Mohammad Javad Hajipour, Forough Ghasemi, Haniyeh Aghaverdi, Mohammad Raoufi, Uwe Linne, Fatemeh Atyabi, Iraj Nabipour, Morteza Azhdarzadeh, Hossein Derakhshankhah, Alireza Lotfabadi, Afshar Bargahi, Zahra Alekhamis, Afsaneh Aghaie, Ehsan Hashemi, Abbas Tafakhori, Vajiheh Aghamollaii, Marzie Maserat Mashhadi, Sara Sheibani, Hojatollah Vali, Morteza Mahmoudi
Sensing of Alzheimer’s Disease and Multiple Sclerosis Using Nano-Bio Interfaces
Abstract: It is well understood that patients with different diseases may have a variety of specific proteins (e.g., type, amount, and configuration) in their plasmas. When nanoparticles (NPs) are exposed to these plasmas, the resulting coronas may incorporate some of the disease-specific proteins. Using gold (Au) NPs with different surface properties and corona composition, we have developed a colorimetric sensor array for the discrimination and detection of two neurodegenerative diseases, Alzheimer’s disease (AD) and multiple sclerosis (MS). Applying a variety of techniques, including UV-visible spectra, array response analyses, and liquid chromatography-tandem mass spectrometry, we found the corona-NP complexes, obtained from different human serums, had distinct protein composition, including some specific proteins that are known as AD and MS biomarkers. The array responses, analyzed by chemometrics and statistical methods, demonstrate promising capabilities of the sensor to unambiguously identify and discriminate AD and MS. The developed sensor array might enable a simple, inexpensive, and rapid detection/discrimination of neurodegenerative diseases.
Yan Lian, Lily Dongxia Xiao, Fan Zeng, Xianmu Wu, Zhen Wang, Hui Ren (Handling Associate Editor: Jin-Tai Yu)
The Experiences of People with Dementia and Their Caregivers in Dementia Diagnosis
Abstract: Background: People can live well with dementia if they are diagnosed early and receive early interventions and appropriate dementia management and care. However, dementia is currently under-detected and under-diagnosed. The diagnosis rate is around 50% only in higher-income countries and 5-10% only in low- and middle-income countries. Studies on consumers’ experiences in engaging in dementia diagnosis in a socio-cultural context are much needed in order to generate research evidence to inform person-centered dementia care and services. Objective: The aim of the study was to understand the experiences of people with dementia and their caregivers in engaging in dementia diagnosis. Methods: An interpretative study design informed by Gadamer's hermeneutic principles was applied to the present study to achieve the aim of the study. The study was strengthened by applying a social ecological framework to the study design. In total, 23 participants contributed to the interviews or focus group. Thematic analysis was applied to data analysis. Results: Four themes were determined from data and described as: capabilities to detect the memory loss in an early stage, perceptions and beliefs of dementia in the community, different journeys toward the diagnosis and expectations of a smooth journey for others. These findings illuminate a social ecological perspective of improving early detection and timely diagnosis of dementia in the community settings. Conclusion: The findings of this study have implications for policy, resource, and practice development. Consumers expect that government subsidized dementia care services in primary care and specialist care settings are needed in order to enable consumer-driven timely diagnosis and dementia management in home care settings.
Ersilia De Lorenzi, Marcella Chiari, Raffaella Colombo, Marina Cretich, Laura Sola, Renzo Vanna, Paola Gagni, Federica Bisceglia, Carlo Morasso, Jennifer S. Lin, Moonhee Lee, Patrick L. McGeer, Annelise E. Barron (Handling Associate Editor: Benedetta Nacmias)
Evidence that the Human Innate Immune Peptide LL-37 may be a Binding Partner of Amyloid-β and Inhibitor of Fibril Assembly
Abstract: Background: Identifying physiologically relevant binding partners of amyloid-β (Aβ) that modulate in vivo fibril formation may yield new insights into Alzheimer's disease (AD) etiology. Human cathelicidin peptide, LL-37, is an innate immune effector and modulator, ubiquitous in human tissues and expressed in myriad cell types. Objective: We present in vitro experimental evidence and discuss findings supporting a novel hypothesis that LL-37 binds to Aβ42 and can modulate Aβ fibril formation. Methods: Specific interactions between LL-37 and Aβ (with Aβ in different aggregation states, assessed by capillary electrophoresis) were demonstrated by surface plasmon resonance imaging (SPRi). Morphological and structural changes were investigated by transmission electron microscopy (TEM) and circular dichroism (CD) spectroscopy. Neuroinflammatory and cytotoxic effects of LL-37 alone, Aβ42 alone, and LL-37/Aβ complexes were evaluated in human microglia and neuroblastoma cell lines (SH-SY5Y). Results: SPRi shows binding specificity between LL-37 and Aβ, while TEM shows that LL-37 inhibits Aβ42 fibril formation, particularly Aβ’s ability to form long, straight fibrils characteristic of AD. CD reveals that LL-37 prevents Aβ42 from adopting its typical β-type secondary structure. Microglia-mediated toxicities of LL-37 and Aβ42 to neurons are greatly attenuated when the two peptides are co-incubated prior to addition. We discuss the complementary biophysical characteristics and AD-related biological activities of these two peptides. Conclusion: Based on this body of evidence, we propose that LL-37 and Aβ42 may be natural binding partners, which implies that balanced (or unbalanced) spatiotemporal expression of the two peptides could impact AD initiation and progression.
Thomas D. Parsons, Michael Barnett (Handling Associate Editor: Julie Robillard)
Validity of a Newly Developed Measure of Memory: Feasibility Study of the Virtual Environment Grocery Store
Abstract: Virtual reality-based neuropsychological assessments proffer the potential to address the limited ecological validity of pen-and-paper measures of memory. To investigate the construct validity of a newly developed virtual reality measure of memory, the Virtual Environment Grocery Store (VEGS), traditional neuropsychological measures of memory and executive functioning were administered to 48 older adults and 55 young adults. Performances on the VEGS memory tasks and the traditional neuropsychological assessments of memory were positively correlated, indicating that memory for VEGS content was similar to memory for traditional paper-and-pencil measures. The older adults performed significantly worse than young adults on the VEGS and the California Verbal Learning Test, but the DKEFS Color-Word Interference failed to differentiate the groups. Furthermore, significant differences were found between groups for the VEGS memory and multitasking measures. The VEGS has the advantage over traditional measures of providing objective measurement of individual components of memory in simulations of everyday activities.
Shweta Bagewadi Kawalia*, Tamara Raschka*, Mufassra Naz, Ricardo de Matos Simoes, Philipp Senger, Martin Hofmann-Apitius *These authors contributed equally to this work.
Analytical Strategy to Prioritize Alzheimer’s Disease Candidate Genes in Gene Regulatory Networks Using Public Expression Data
Abstract: Alzheimer’s disease (AD) progressively destroys cognitive abilities in the aging population with tremendous effects on memory. Despite recent progress in understanding the underlying mechanisms, high drug attrition rates have put a question mark behind our knowledge about its etiology. Re-evaluation of past studies could help us to elucidate molecular-level details of this disease. Several methods to infer such networks exist, but most of them do not elaborate on context specificity and completeness of the generated networks, missing out on lesser-known candidates. In this study, we present a novel strategy that corroborates common mechanistic patterns across large scale AD gene expression studies and further prioritizes potential biomarker candidates. To infer gene regulatory networks (GRNs), we applied an optimized version of the BC3Net algorithm, named BC3Net10, capable of deriving robust and coherent patterns. In principle, this approach initially leverages the power of literature knowledge to extract AD specific genes for generating viable networks. Our findings suggest that AD GRNs show significant enrichment for key signaling mechanisms involved in neurotransmission. Among the prioritized genes, well-known AD genes were prominent in synaptic transmission, implicated in cognitive deficits. Moreover, less intensive studied AD candidates (STX2, HLA-F, HLA-C, RAB11FIP4, ARAP3, AP2A2, ATP2B4, ITPR2, and ATP2A3) are also involved in neurotransmission, providing new insights into the underlying mechanism. To our knowledge, this is the first study to generate knowledge-instructed GRNs that demonstrates an effective way of combining literature-based knowledge and data-driven analysis to identify lesser known candidates embedded in stable and robust functional patterns across disparate datasets.
Dongmei Wang, Xiaozhuan Liu, Yumei Liu, Sanqiang Li, Chenying Wang
The Effects of Cardiotrophin-1 on Early Synaptic Mitochondrial Dysfunction and Synaptic Pathology in APPswe/PS1dE9 Mice
Abstract: The coexistence of neuronal mitochondrial pathology and synaptic dysfunction is an early pathological feature of Alzheimer’s disease (AD). Cardiotrophin-1 (CT-1) has been shown to exhibit impressive neuroprotective effects. Previous studies have shown positive effects of CT-1 on brain glucose metabolism and cognition in APPswe/PS1dE9 transgenic mice; however, little is known about the effects of CT-1 on early synaptic mitochondrial dysfunction and resultant synaptic pathology in the brain. In this study, 4-month-old transgenic mice with brain tissue-specific CT-1 expression were used alone or in combination with APPswe/PS1dE9 transgenic mice to evaluate the effect of CT-1 on synaptic mitochondrial dysfunction and resultant synaptic pathology, and cryptic memory deficits in the APPswe/PS1dE9 transgenic mice. The potential mechanism of action of CT-1 was also examined. Young CT-1×APPswe/PS1dE9 transgenic mice exhibited improvements in long-term learning and memory ability and ameliorations of synaptic mitochondrial/synaptic impairments compared to young APPswe/PS1dE9 transgenic mice. Moreover, CT-1 upregulated the expression of AMPAR and increased AMP-activated protein kinase (AMPK) activity in the hippocampus of APPswe/PS1dE9 transgenic mice. However, AMPK inhibition through shRNA knockdown of AMPKα blocked the neuroprotective effects of CT-1 on the expression of AMPAR and mitochondrial/synaptic dysfunction in Aβ-treated mouse neurons. These results suggest that CT-1 may be a potent candidate for the early prevention and treatment of AD.
Chunfei Li, David A. Loewenstein, Ranjan Duara, Mercedes Cabrerizo, Warren Barker, Malek Adjouadi; for the Alzheimer’s Disease Neuroimaging Initiative (Handling Associate Editor: Saeid Taheri)
The Relationship of Brain Amyloid Load and APOE Status to Regional Cortical Thinning and Cognition in the ADNI Cohort
Abstract: Background: Both amyloid (Aβ) load and APOE4 allele are associated with neurodegenerative changes in Alzheimer’s disease (AD) prone regions and with risk for cognitive impairment. Objective: To evaluate the unique and independent contribution of APOE4 allele status (E4+\E4-), Aβ status (Amy+\Amy-), and combined APOE4 and Aβ status on regional cortical thickness (CoTh) and cognition among participants diagnosed as cognitively normal (CN, n=251), early mild cognitive impairment (EMCI, n=207), late mild cognitive impairment (LMCI, n=196), and mild AD (n=162) from the ADNI. Methods: A series of two-way ANCOVAs with post-hoc Tukey HSD tests, controlling independently for Aβ and APOE4 status and age were examined. Results: Among LMCI and AD participants, cortical thinning was widespread in association with Amy+ status, whereas in association with E4+ status only in the inferior temporal and medial orbito-frontal regions. Among CN and EMCI participants, E4+ status, but not Amy+ status, was independently associated with increased CoTh, especially in limbic regions [e.g., in the entorhinal cortex, CoTh was 0.123 mm greater (p = 0.002) among E4+ than E4- participants]. Among CN and EMCI, both E4+ and Amy+ status were independently associated with cognitive impairment, which was greatest among those with combined E4+ and Amy+ status. Conclusion: Decreased CoTh is independently associated with Amy+ status in many brain regions, but with E4+ status in very restricted number of brain regions. Among CN and EMCI participants, E4+ status is associated with increased CoTh, in medial and inferior temporal regions, although cognitive impairment at this state is independently associated with Amy+ and E4+ status. These findings imply a unique pathophysiological mechanism for E4+ status in AD and its progression.
Junhua Ding*, Keliang Chen*, Weibin Zhang, Ming Li, Yan Chen, Qing Yang, Yingru Lv, Qihao Guo, Zaizhu Han (Handling Associate Editor: Sharon Savage) *These authors contributed equally to this work.
Topological Alterations and Symptom-Relevant Modules in the Whole-Brain Structural Network in Semantic Dementia
Abstract: Background: Semantic dementia (SD) is characterized by a selective decline in semantic processing. Although the neuropsychological pattern of this disease has been identified, its topological global alterations and symptom-relevant modules in the whole-brain anatomical network have not been fully elucidated. Objective: This study aims to explore the topological alteration of anatomical network in SD and reveal the modules associated with semantic deficits in this disease. Methods: We first constructed the whole-brain white-matter networks of 20 healthy controls and 19 patients with SD. Then, the network metrics of graph theory were compared between these two groups. Finally, we separated the network of SD patients into different modules and correlated the structural integrity of each module with the severity of the semantic deficits across patients. Results: The network of the SD patients presented a significantly reduced global efficiency, indicating that the long-distance connections were damaged. The network was divided into the following four distinctive modules: the left temporal/occipital/parietal, frontal, right temporal/occipital, and frontal/parietal modules. The first two modules were associated with the semantic deficits of SD. Conclusion: These findings illustrate the skeleton of the neuroanatomical network of SD patients and highlight the key role of the left temporal/occipital/parietal module and the left frontal module in semantic processing.
Adrian Wong, Ching-hang Fong, Vincent Mok, Kam Tat Leung, Raymond Kai-yu Tong (Handling Associate Editor: Stelios Zygouris)
Computerized Cognitive Screen (CoCoSc): A Self-Administered Computerized Test for Screening for Cognitive Impairment in Community Social Centers
Abstract: Background: Computerized cognitive tests may serve as a preliminary, low-cost method to identify individuals with suspected cognitive impairment in the community. Objective: To develop a self-administered computerized test, namely the “Computerized Cognitive Screen (CoCoSc), Hong Kong version”, for screening of individuals with cognitive impairment (CI) in community settings. Methods: The CoCoSc is a 15-min computerized cognitive screen covering memory, executive functions, orientation, attention and working memory, and prospective memory administered on a touchscreen computer. Individuals with CI and cognitively normal controls were administered the CoCoSc and the Montreal Cognitive Assessment (MoCA). Validity of the CoCoSc was assessed based on the relationship with the MoCA using Pearson correlation. Receiver operating characteristic curve (ROC) was used to examine the ability of the CoCoSc to differentiate CI from controls. Results: Fifty-nine individuals with CI and 101 controls were recruited. Seventy-five (46.9%) participants had ≤6 years of education. Performance on the CoCoSc differed between normal and CI groups in both low and high education subgroups. Total scores of the CoCoSc and MoCA were significantly correlated (r = 0.71, p < 0.001). The area under ROC was 0.78, p < 0.001 for the CoCoSc total score in differentiating the CI group from the cognitively normal group. A cut-off of ≤ 30 on the CoCoSc was associated with a sensitivity of 0.78 and specificity of 0.69. The CoCoSc was well accepted by attendees of community social centers. Conclusion: The CoCoSc is a promising computerized cognitive screen for self-administration in community social centers. It is feasible for testing individuals with high or low education levels.
Brianne M. Bettcher, M. Colin Ard, Bruce R. Reed, Andreana Benitez, Amanda Simmons, Eric B. Larson, Josh A. Sonnen, Thomas J. Montine, Ge Li, C. Dirk Keene, Paul K. Crane, Dan Mungas (Handling Associate Editor: Kaarin Anstey)
Association between Cholesterol Exposure and Neuropathological Findings: The ACT Study
Abstract: We characterized the relationship between late life cholesterol exposure and neuropathological outcomes in a community-based, older adult cohort. Adult Changes in Thought (ACT) is a cohort study that enrolls consenting, randomly selected, non-demented people aged ≥65 from a healthcare delivery system. We used late life HDL and total cholesterol lab values from Group Health computerized records, and calculated HDL and non-HDL levels. We evaluated neuropathological outcomes of Alzheimer’s disease, cerebral amyloid angiopathy, vascular brain injury, and Lewy body disease. Using linear mixed models with age and antilipemic medication as predictors, we obtained predicted cholesterol values at age 70 and 10 years prior to death for individuals with available cholesterol data in 10-year exposure windows. We used logistic regression to determine whether predicted late life cholesterol levels were associated with neuropathological outcomes controlling for age at death, APOE genotype, sex, and their interactions with cholesterol levels. 525 decedents came to autopsy by 08/2014. Of these, plasma cholesterol concentration was available for 318 (age 70, model 1) and 396 (10 years prior to death, model 2) participants. We did not find associations between late life cholesterol and Alzheimer’s disease neuropathological changes, and there were no associations between cholesterol levels and amyloid angiopathy or vascular brain injury. We observed an association between predicted non-HDL cholesterol at age 70 and Lewy body disease. Our study suggests an association between late life non-HDL cholesterol exposure and Lewy body disease. We did not observe associations between late life cholesterol levels and Braak stage or CERAD score.
Dan Li, Nan Hu, Yueyi Yu, Aihong Zhou, Fangyu Li, Jianping Jia (Handling Associate Editor: Jin-Tai Yu)
Trajectories of Multidimensional Caregiver Burden in Chinese Informal Caregivers for Dementia: Evidence from Exploratory and Confirmatory Factor Analysis of the Zarit Burden Interview
Abstract: Background: Despite its popularity, the latent structure of 22-item Zarit Burden Interview (ZBI) remains unclear. There has been no study exploring how caregiver multidimensional burden changed. Objective: The aim of the work was to validate the latent structure of ZBI and to investigate how multidimensional burden evolves with increasing global burden. Methods: We studied 1,132 dyads of dementia patients with informal caregivers. The caregivers completed the ZBI and a questionnaire regarding caregiving. The total sample was randomly split into two equal subsamples. Exploratory factor analysis (EFA) was performed in the first subsample. In the second subsample, confirmatory factor analysis (CFA) was conducted to validate the model generated from EFA. The mean of weighted factor score was calculated to assess the change of dimension burden against the increasing ZBI total score. Results: The result of EFA and CFA supported that a five-factor structure, including role strain, personal strain, incompetency, dependency, and guilt, had the best goodness-of-fit. The trajectories of multidimensional burden suggested that three different dimensions (guilt, role strain and personal strain) became the main subtype of burden in sequence as the ZBI total score increased from mild to moderate. Factor dependency contributed prominently to the total burden in severe stage. Conclusion: The five-factor ZBI is a psychometrically robust measure for assessing multidimensional burden in Chinese caregivers. The changes of multidimensional burden have deepened our understanding of the psychological characteristics of caregiving beyond a single total score and may be useful for developing interventions to reduce caregiver burden.
Simone Lista, Nicola Toschi, Filippo Baldacci, Henrik Zetterberg, Kaj Blennow, Ingo Kilimann, Stefan J. Teipel, Enrica Cavedo, Antonio Melo dos Santos, Stéphane Epelbaum, Foudil Lamari, Bruno Dubois, Robert Nisticò, Roberto Floris, Francesco Garaci, Harald Hampel, for the Alzheimer Precision Medicine Initiative (APMI) (Handling Associate Editor: Roberta Ghidoni)
Cerebrospinal Fluid Neurogranin as a Biomarker of Neurodegenerative Diseases: A Cross-Sectional Study
Abstract: We investigated cerebrospinal fluid (CSF) concentrations of the postsynaptic biomarker neurogranin at baseline in cognitively healthy controls (HC) compared to individuals with mild cognitive impairment (MCI), patients with Alzheimer’s disease (AD) dementia, and patients with frontotemporal dementia (FTD). CSF neurogranin was quantified using an in-house immunoassay in a cross-sectional multicenter study of 108 participants [AD dementia (n = 35), FTD (n = 9), MCI (n = 41), cognitively HC (n = 23)]. CSF neurogranin concentrations were significantly higher in AD patients compared with both HC subjects and FTD patients, suggesting that increased CSF neurogranin concentrations may indicate AD-related pathophysiology. CSF neurogranin was independently associated with both total tau and hyperphosphorylated tau proteins, whereas a non-significant correlation with the 42-amino acid-long amyloid-β peptide was evident. CSF neurogranin, however, was not superior to core AD biomarkers in differentiating HC from the three diagnostic groups, and it did not improve their diagnostic accuracy. We conclude that further classification and longitudinal studies are required to shed more light into the potential role of neurogranin as a pathophysiological biomarker of neurodegenerative diseases.
Murat Bilgel, Rebecca L. Koscik, Yang An, Jerry L. Prince, Susan M. Resnick, Sterling C. Johnson, Bruno M. Jedynak (Handling Associate Editor: Michael Malek-Ahmadi)
Temporal Order of Alzheimer’s Disease-Related Cognitive Marker Changes in BLSA and WRAP Longitudinal Studies
Abstract: Investigation of the temporal trajectories of currently used neuropsychological tests is critical to identifying earliest changing measures on the path to dementia due to Alzheimer’s disease (AD). We used the Progression Score (PS) method to characterize the temporal trajectories of measures of verbal memory, executive function, attention, processing speed, language, and mental status using data spanning normal cognition, mild cognitive impairment, and AD from 1,661 participants with a total of 7,839 visits (age at last visit 77.6 SD 9.2) in the Baltimore Longitudinal Study of Aging (BLSA) and 1510 participants with a total of 3,473 visits (age at last visit 59.5 SD 7.4) in the Wisconsin Registry for Alzheimer’s Prevention (WRAP). This method aligns individuals in time based on the similarity of their longitudinal measurements to reveal temporal trajectories. As a validation of our methodology, we explored the associations between the individualized cognitive progression scores (Cog‑PS) computed by our method and clinical diagnosis. Digit span tests were the first to show declines in both data sets, and were detected mainly among cognitively normal individuals. These were followed by tests of verbal memory, which were in turn followed by Trail Making Tests, Boston Naming Test, and Mini-Mental State Examination. Differences in Cog-PS across the clinical diagnosis and APOE ε4 groups were statistically significant, highlighting the potential use of Cog-PS as individualized indicators of disease progression. Identifying cognitive measures that are changing in preclinical AD can lead to the development of novel cognitive tests that are finely tuned to detecting earliest changes.
Alden L. Gross, Haidong Lu, Lucy Meoni, Joseph J. Gallo, Jennifer A. Schrack, A. Richey Sharrett
Physical Activity in Midlife is not associated with Cognitive Health in Later Life among Cognitively Normal Older Adults
Abstract: Background: Links between physical activity and dementia are based primarily on cross-sectional data or studies with unsatisfactory follow-up. Objective: We leveraged three decades of follow-up from an established cohort to determine whether physical activity in midlife is associated with late-life cognition and dementia. Methods: The Johns Hopkins Precursors study (n=646) enrolled participants from 1948-1964 and administered questions about physical activity, from which we calculated metabolic equivalents (MET h/day), and exercise from 1978-present. Cognitive tests were administered in 2008. Dementia was adjudicated through 2011. To characterize associations with midlife physical activity, we used linear regression for cognitive tests and Cox proportional hazards models for dementia onset. Models adjusted for age, sex, smoking, diabetes, and hypertension. Results: No physical activity measure from 1978 was associated with late-life cognition or onset of dementia. Both MET h/day (β=0.007, 95% CI: 0.002, 0.013) and regular exercise (β=0.357, 95% CI: 0.202, 0.513) in 2006, however, were associated with better cognition in 2008. Conclusion: Findings from this 30-year cohort study that physical activity measured recently, but not in mid-life, is associated with late-life cognition fits with null findings from randomized trials and other observational studies with extensive follow-up. Cross-sectional findings may be misleading due to reverse causation.
Emma Lawrence, Carolin Vegvari, Alison Ower, Christoforos Hadjichrysanthou, Frank De Wolf, Roy M. Anderson (Handling Associate Editor: M. Arfan Ikram)
A Systematic Review of Longitudinal Studies Which Measure Alzheimer’s Disease Biomarkers
Abstract: Alzheimer’s disease (AD) is a progressive and fatal neurodegenerative disease, with no effective treatment or cure. A gold standard therapy would be treatment to slow or halt disease progression; however, knowledge of causation in the early stages of AD is very limited. In order to determine effective endpoints for possible therapies, a number of quantitative surrogate markers of disease progression have been suggested, including biochemical and imaging biomarkers. The dynamics of these various surrogate markers over time, particularly in relation to disease development, are, however, not well characterized. We reviewed the literature for studies that measured cerebrospinal fluid or plasma amyloid-β and tau, or took magnetic resonance image or fluorodeoxyglucose/Pittsburgh compound B‑positron electron tomography scans, in longitudinal cohort studies. We summarized the properties of the major cohort studies in various countries, commonly used diagnosis methods and study designs. We have concluded that additional studies with repeat measures over time in a representative population cohort are needed to address the gap in knowledge of AD progression. Based on our analysis, we suggest directions in which research could move in order to advance our understanding of this complex disease, including repeat biomarker measurements standardization and increased sample sizes.
Nicolai Franzmeier, Julia C. Hartmann, Alexander N.W. Taylor, Migeul Á. Araque Caballero, Lee Simon-Vermot, Katharina Buerger, Lana M. Kambeitz-Ilankovic, Birgit Ertl-Wagner, Claudia Mueller, Cihan Catak, Daniel Janowitz, Robert Stahl, Martin Dichgans, Marco Duering, Michael Ewers (Handling Associate Editor: Daniela Galimberti)
Left Frontal Hub Connectivity during Memory Performance Supports Reserve in Aging and Mild Cognitive Impairment
Abstract: Reserve in aging and Alzheimer’s disease (AD) is defined as maintaining cognition at a relatively high level in the presence of neurodegeneration, an ability often associated with higher education among other life factors. Recent evidence suggests that higher resting-state functional connectivity within the frontoparietal control network, specifically the left frontal cortex (LFC) hub, contributes to higher reserve. Following up these previous resting-state fMRI findings, we probed memory-task related functional connectivity of the LFC hub as a neural substrate of reserve. In elderly controls (CN, n = 37) and patients with mild cognitive impairment (MCI, n = 17), we assessed global connectivity of the LFC hub during successful face-name association learning, using generalized psychophysiological interaction analyses. Reserve was quantified as residualized memory performance, accounted for gender and proxies of neurodegeneration (age, hippocampus atrophy, and APOE genotype). We found that greater education was associated with higher LFC-connectivity in both CN and MCI during successful memory. Furthermore, higher LFC-connectivity predicted higher residualized memory (i.e., reserve). These results suggest that higher LFC-connectivity contributes to reserve in both healthy and pathological aging.
Stephanie Villarreal, Fuqiang Zhao, Lynn A. Hyde, Daniel Holder, Thomas Forest, Marie Sondey, Xia Chen, Cyrille Sur, Eric M. Parker, Matthew E. Kennedy
Chronic Verubecestat Treatment Suppresses Amyloid Accumulation in Advanced Aged Tg2576-AβPPswe Mice without Inducing Microhemorrhage
Abstract: Verubecestat is a potent BACE1 enzyme inhibitor currently being investigated in Phase III trials for the treatment of mild-to-moderate and prodromal Alzheimer’s disease. Multiple anti-amyloid immunotherapies have been dose-limited by adverse amyloid related imaging abnormalities such as vasogenic edema (ARIA-E) and microhemorrhage (ARIA-H) observed in human trials and mice. Verubecestat was tested in a 12-week nonclinical study for the potential to exacerbate microhemorrhage (ARIA-H) profiles in 18-22-month-old post-plaque Tg2576-AβPPswe mice. Animals were treated with verubecestat or controls including the anti-Aβ antibody analog of bapineuzumab (3D6) as a positive control for ARIA induction. ARIA-H was measured using in-life longitudinal T2*-MRI and Prussian blue histochemistry at study end. Verubecestat reduced plasma and cerebrospinal fluid Aβ40 and Aβ42 by >90% and 62% to 68%, respectively. The ARIA-H profile of verubecestat-treated mice was not significantly different than controls. Anti-Aβ treatment significantly increase ARIA-H detected by Prussian blue staining; however, anti-Aβ antibody treatment did not impact plaque status. Verubecestat treatment significantly suppressed the accumulation of total levels of brain Aβ40 and Aβ42 and Thioflavin S positive plaque load. Stereological analysis of cortex and hippocampus plaque load similarly revealed significantly reduced area of Aβ immunoreactivity and reduced plaque number in verubecestat-treated animals compared to controls. The absence of elevated ARIA events in verubecestat-treated mice was associated with a significant reduction in the level of accumulated CNS amyloid pathology and brain Aβ peptides; effects consistent with the desired therapeutic mechanism of verubecestat in AD patients. These data will be compared with longitudinal MRI profiles from ongoing clinical trials.
Michail B. Evgen’ev, George S. Krasnov, Inna V. Nesterova, David G. Garbuz, Vadim L. Karpov, Alexey V. Morozov, Anastasiya V. Snezhkina, Alexander N. Samokhin, Alexander Sergeev, Natalia V. Bobkova
Molecular Mechanisms Underlying Neuroprotective Effect of Intranasal Administration of Human Hsp70 in Mouse Model of Alzheimer’s Disease
Abstract: Heat shock protein 70, encoded by the HSPA1A gene in humans, is a key component of the machinery that protects neuronal cells from various stress conditions and whose production significantly declines during the course of aging and as a result of several neurodegenerative diseases. Herein, we investigated whether sub-chronic intranasal administration of exogenous Hsp70 (eHsp70) exerts a neuroprotective effect on the temporal cortex and areas of the hippocampus in transgenic 5XFAD mice, a model of Alzheimer’s disease. The quantitative analysis of neuronal pathologies in the compared groups, transgenic (Tg) versus non-transgenic (nTg), revealed high level of abnormalities in the brains of transgenic mice. Treatment with human recombinant Hsp70 had profound rejuvenation effect on both neuronal morphology and functional state in the temporal cortex and hippocampal regions in transgenic mice. Hsp70 administration had a smaller, but still significant, effect on the functional state of neurons in non-transgenic mice as well. Using deep sequencing, we identified multiple differentially expressed genes (DEGs) in the hippocampus of transgenic and non-transgenic mice. Furthermore, this analysis demonstrated that eHsp70 administration strongly modulates the spectrum of DEGs in transgenic animals, reverting to a pattern similar to that observed in non-transgenic age-matched mice, which included upregulation of genes responsible for amine transport, transmission of nerve impulses and other pathways that are impaired in 5XFAD mice. Overall, our data indicate that Hsp70 treatment may be an effective therapeutic against old age diseases of the Alzheimer’s type.
Adriana Seelye, Nora Mattek, Nicole Sharma, Phelps Witter IV, Ariella Brenner, Katherine Wild, Hiroko Dodge, Jeffrey Kaye
Passive Assessment of Routine Driving with Unobtrusive Sensors: A New Approach for Identifying and Monitoring Functional Level in Normal Aging and Mild Cognitive Impairment
Abstract: Background: Driving is a key functional activity for many older adults, and changes in routine driving may be associated with emerging cognitive decline due to early neurodegenerative disease. Current methods for assessing driving such as self-report are inadequate for identifying and monitoring subtle changes in driving patterns that may be the earliest signals of functional change in developing mild cognitive impairment (MCI). Objective: This proof of concept study aimed to establish the feasibility of continuous driving monitoring in a sample of cognitively normal and MCI older adults for an average of 206 days using an unobtrusive driving sensor and demonstrate that derived sensor-based driving metrics could effectively discriminate between MCI and cognitively intact groups. Methods: Novel objective driving measures derived from 6 months of routine driving monitoring were examined in older adults with intact cognition (n=21) and MCI (n=7) who were enrolled in the Oregon Center for Aging and Technology (ORCATECH) longitudinal assessment program. Results: Unobtrusive continuous monitoring of older adults’ routine driving using a driving sensor was feasible and well accepted. MCI participants drove fewer miles and spent less time on the highway per day than cognitively intact participants. MCI drivers showed less day-to-day fluctuations in their driving habits than cognitively intact drivers. Conclusion: Sensor-based driving measures are objective, unobtrusive, and can be assessed every time a person drives his or her vehicle to identify clinically meaningful changes in daily driving. This novel methodology has the potential to be useful for the early detection and monitoring of changes in daily functioning within individuals.
Michaela Defrancesco, Josef Marksteiner, Georg Kemmler, Walter Wolfgang Fleischhacker, Imrich Blasko, Eberhard A. Deisenhammer
Severity of Depression Impacts Imminent Conversion from Mild Cognitive Impairment to Alzheimer’s Disease
Abstract: Background: Mild cognitive impairment (MCI) has been suggested to represent a prodromal stage of dementia and to confer a high risk for conversion to dementia Alzheimer’s type (DAT). Objectives: In this study, we examined the predictive value of depressive symptoms and neuropsychological variables on conversion of MCI to DAT. Methods: Neuropsychological and clinical follow-up data of 260 MCI patients seen at the Psychiatric Memory Clinic of the Medical University of Innsbruck between 2005 and 2015 were analyzed retrospectively. Depression was assessed using the Geriatric Depression Scale (GDS). Potential predictors of conversion from MCI to DAT were analyzed by logistic regression analyses and additional survival-analytic methods. Results: Of the 260 patients (mean age 71.5±7.7 years), 83 (32%) converted to DAT within a mean follow-up time of 3.2± 2.2 years and estimated one-year conversion rate of 10.1%. The univariate analysis showed with few exceptions (gender, use of antidepressants, low GDS score) group differences at baseline in patients converted to DAT compared to stable MCI patients. Logistic regression analysis as well as survival analysis revealed moderate to severe depression together with higher age and specific cognitive deficits as predictors of conversion from MCI to DAT. Conclusion: Our results support the predictive value of different neuropsychological measures on the progression of DAT. In addition, we found a strong negative influence of depression on conversion to DAT in MCI patients. These results emphasize the importance of assessing depressive symptoms in the early stages of DAT when evaluating the conversion from MCI to DAT.
Honghai Hong, Yang Li, Baochang Su
Identification of Circulating miR-125b as a Potential Biomarker of Alzheimer’s Disease in APP/PS1 Transgenic Mouse
Abstract: Alzheimer’s disease (AD) is the most common form of dementia, characterized by progressive decline in cognitive abilities of the affected individuals. Biological markers are essential to identify individuals at early stages of the disease for timely therapeutic intervention. Currently, pathological biomarkers are detected either through cerebrospinal fluid analysis or brain imaging, or postmortem, all of which are expensive, invasive, or time consuming. Recently, some studies have shown that circulating miR-125b, miR-181c, miR-9, miR-191-5p, miR-26b-3p, and miR-28-3p may be biomarkers of AD. However, those potential biomarkers are not validated in an AD mouse model. In the current study, we found that circulating miR-125b, miR-9, and miR-191-5p are downregulated, and miR-28-3p is upregulated in an APP/PS1 transgenic mouse model of AD. Furthermore, the correlation analysis shows a positive correlation between the expression of miR-125b and cognitive function of the APP/PS1 transgenic mouse. Moreover, we also determined that the level of serum miR-125b, miR-9, and miR-191-5p were reversed in EGCG-treated APP/PS1 transgenic mouse models. Finally, the expression of miR-125b was significantly downregulated in EGCG-treated SH-SY5Y cells.
Shireen Sindi, Tiia Ngandu, Iiris Hovatta, Ingemar Kåreholt, Riitta Antikainen, Tuomo Hänninen, Esko Levälahti, Tiina Laatikainen, Jaana Lindström, Teemu Paajanen, Markku Peltonen, Dharma Singh Khalsa, Benjamin Wolozin, Timo Strandberg, Jaakko Tuomilehto, Hilkka Soininen, Miia Kivipelto, Alina Solomon, for the FINGER study group
Baseline Telomere Length and Effects of a Multidomain Lifestyle Intervention on Cognition: The FINGER Randomized Controlled Trial
Abstract: Leukocyte telomere length (LTL) is a biomarker of aging, and it is associated with lifestyle. It is currently unknown whether LTL is associated with the response to lifestyle interventions. The goal is to assess whether baseline LTL modified the cognitive benefits of a 2-year multidomain lifestyle intervention (exploratory analyses). The Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) was a 2-year randomized controlled trial including 1,260 people at risk of cognitive decline, aged 60-77 years identified from the general population. Participants were randomly assigned to the lifestyle intervention (diet, exercise, cognitive training, and vascular risk management) and control (general health advice) groups. Primary outcome was change in cognition (comprehensive neuropsychological test battery). Secondary outcomes were changes in cognitive domains: memory, executive functioning, and processing speed. 775 participants (392 control, 383 intervention) had baseline LTL (peripheral blood DNA). Mixed effects regression models with maximum likelihood estimation were used to analyze change in cognition as a function of randomization group, time, baseline LTL, and their interaction. Intervention and control groups did not significantly differ at baseline. Shorter LTL was related to less healthy baseline lifestyle. Intervention benefits on executive functioning were more pronounced among those with shorter baseline LTL (p-value for interaction was 0.010 adjusted for age and sex, and 0.007 additionally adjusted for baseline lifestyle factors). The FINGER intervention cognitive benefits were more pronounced with shorter baseline LTL, particularly for executive functioning, indicating that the multidomain lifestyle intervention was especially beneficial among higher-risk individuals.