Mehmet Murat Koseoglu, Andrés Norambuena, Elizabeth R. Sharlow, John S. Lazo, George S. Bloom (Handling Associate Editor: Hans-Ulrich Demuth)
Aberrant Neuronal Cell Cycle Re-Entry: The Pathological Confluence of Alzheimer's Disease and Brain Insulin Resistance, and its Relation to Cancer
Abstract: Aberrant neuronal cell cycle re-entry (CCR) is a phenomenon that precedes and may mechanistically lead to a majority of the neuronal loss observed in Alzheimer’s disease (AD). Recent developments concerning the regulation of aberrant neuronal CCR in AD suggest that there are potential intracellular signaling “hotspots” in AD, cancer, and brain insulin resistance, the latter of which is characteristically associated with AD. Critically, these common signaling nodes across different human diseases may represent currently untapped therapeutic opportunities for AD. Specifically, repurposing of existing US Food and Drug Administration-approved pharmaco¬logical agents, including experimental therapeutics that target the cell cycle in cancer, may be an innovative avenue for future AD-directed drug discovery and development. In this review we discuss overlapping aspects of AD, cancer, and brain insulin resistance from the perspective of neuronal CCR, and consider strategies to exploit them for prevention or therapeutic intervention of AD.
Hasan A.M.M. Almansoub, Hui Tang, Ying Wu, Ding-Qi Wang, Yacoubou Abdoul Razak Mahaman, Na Wei, Yusra A. M. Almansob, Wei He, Dan Liu (Handling Associate Editor: Ling-Qiang Zhu)
Tau Abnormalities and the Potential Therapy in Alzheimer’s Disease
Abstract: Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases that is characterized by progressive memory loss and two main pathological hallmarks, including the extracellular amyloid plaques and intracellular neurofibrillary tangles. The microtubule-related protein tau is involved in the pathogenesis of many neurological diseases commonly known as tauopathies and is found to be abnormally hyperphosphorylated in AD and accumulated in neurons. Besides hyperphosphorylation, tau also undergoes abnormal glycosylation, ubiquitination, glycation, and other posttranslational modifications. These abnormalities lead to the aberrant aggregation of tau in the synaptic loci in AD. In this review, we highlighted the most recent studies about how tau is abnormally regulated and how those abnormalities play important roles in the pathogenesis of AD.
André de Macêdo Medeiros, Regina Helena Silva
Sex Differences in Alzheimer’s Disease: Where Do We Stand?
Abstract: Alzheimer’s disease (AD) is a neurodegenerative disorder that drastically compromises patients’ and relatives’ quality of life, besides being a significant economic burden to global public health. Its pathophysiology is not completely elucidated yet, hence, the current therapies are restricted to treating the symptoms. Over the years, several epidemiological studies have shown disproportionalities in AD when sex is considered, which has encouraged researchers to investigate the potentiality of sex as a risk factor. Studies in rodent models have been used to investigate mechanistic basis of sex differences in AD, as well as the development of possible new sex-specific therapeutic strategies. However, full knowledge on factors related to this sexual dimorphism remains to be unraveled. Some findings point to differences in genetic and developmental backgrounds either earlier in life or in the aging brain. Herein we summarize the multisystemic framework behind the sex differences in AD and discuss the possible mechanisms involved in these differences raised by the literature so far in an integrative perspective.
Giovanni Rizzo*, Roberto De Blasi*, Rosa Capozzo, Rosanna Tortelli, Maria Rosaria Barulli, Rocco Liguori, Daniela Grasso, Giancarlo Logroscino (Handling Associate Editor: Marco Bozzali) *These authors contributed equally to this work.
Loss of Swallow Tail Sign on Susceptibility-Weighted Imaging in Dementia with Lewy Bodies
Abstract: We assessed nigral dorsolateral hyperintensity (swallow tail sign) at susceptibility-weighted imaging using 3T-MRI in 15 dementia with Lewy bodies (DLB), 11 Alzheimer’s disease (AD), and 8 frontotemporal dementia (FTD) patients and 10 subjects with subjective memory complaint (SMC). More DLB patients lacked nigral hyperintesity (p < 0.05). Sensitivity, specificity, and accuracy of DLB diagnosis were, respectively: 80%, 64%, and 73% versus AD; 80%, 75%, and 78% versus FTD; and 80%, 90%, and 84% versus SMC. Considering bilateral loss, sensitivity decreased (53%) but specificity increased (82-100%). Swallow tail sign loss, especially if bilateral, can be useful for DLB diagnosis.
Donald R. Royall, Raymond F. Palmer
A δ Homolog for Dementia Case Finding with Replication in the Alzheimer’s Disease Neuroimaging Initiative
Abstract: Dementia can be empirically described by the latent dementia phenotype “δ” and its various composite “homologs”. We have explored δ’s blood-based protein biomarkers in the Texas Alzheimer’s Research and Care Consortium (TARCC) study. However, it would be convenient to replicate those associations in the Alzheimer’s Disease Neuroimaging Initiative (ADNI). To this end, we have engineered a δ homolog from observed cognitive performance measures common to both projects. Our findings were replicated in randomly selected 50% splits of TARCC data (Group 1, N = 1,747; Group ,2 N = 1,755), and then independently in ADNI (N = 1,737). The new δ homolog, i.e., “dT2A” (d-TARCC to ADNI), fit the data of both studies well, and was strongly correlated with dementia severity, as rated by the Clinical Dementia Rating Scale “sum of boxes” (TARCC: r = 0.99, p <0.001; ADNI: r = 0.96, p <0.001). dT2A achieved an area under the receiver operating characteristic curve of 0.981 (0.976-0.985) for the discrimination of AD from normal controls in TARCC, and 0.988 (0.983-0.993) in ADNI. dT2A is the 12th δ homolog published to date, and opens the door to independent replications across these and similar studies.
Colleen Pappas, Brent J. Small, Ross Andel, Jan Laczó, Martina Parizkova, Ondrej Lerch, Jakub Hort (Handling Associate Editor: Ramit Ravona-Springer)
Blood Glucose Levels May Exacerbate Executive Function Deficits in Older Adults with Cognitive Impairment
Abstract: Background: Identifying protective factors that promote healthy cognitive aging is of importance due to the growing older adult population. Preventing chronic hyperglycemia may be one such way to preserve cognitive abilities, as high blood glucose levels have been associated with cognitive impairment and decline. Objective: To evaluate the influence of blood glucose levels on cognition among older adults using common neuropsychological tests and a spatial navigation task. Methods: The association between cognitive performance and blood glucose levels was assessed among 117 older adults classified as cognitively healthy, subjective cognitive decline, amnestic mild cognitive impairment, or Alzheimer’s disease dementia from the Czech Brain Aging Study. Cognitive abilities were measured by tests of verbal memory, nonverbal memory, working memory, visuospatial skills, and executive function. A test of spatial navigation known as the Hidden Goal Task was also used. Blood glucose levels were measured by glycosylated hemoglobin A1c (HbA1c). Analyses were performed using multiple linear regression controlling for age, gender, education, depressive symptoms, diabetes, and cognitive status. Results: A significant relationship was observed for HbA1c and executive function performance (beta=-2.46, SE=0.92, p=0.008). Following moderation analysis, this relationship was significant only among those with cognitive impairment (beta=-4.37, SE=1.28, p=0.001, 95% CI [-6.91, -1.83]). Associations between HbA1c and other cognitive domains were not significant (ps>0.05). Conclusions: Higher HbA1c was associated with poorer executive function among persons with cognitive impairment, but not with performance on other cognitive domains. Maintaining proper glucoregulation may help preserve executive function performance among cognitively impaired older adults.
May J. Reed, Mamatha Damodarasamy, Jasmine L. Pathan, Christina K. Chan, Charles Spiekerman, Thomas N. Wight, William A. Banks, Anthony J. Day, Robert B. Vernon, C. Dirk Keene
Increased Hyaluronan and TSG-6 in Association with Neuropathologic Changes of Alzheimer’s Disease
Abstract: Little is known about the extracellular matrix (ECM) during progression of AD pathology. Brain ECM is abundant in hyaluronan (HA), a non-sulfated glycosaminoglycan synthesized by HA synthases (HAS) 1–3 in a high molecular weight (MW) form that is degraded into lower MW fragments. We hypothesized that pathologic severity of AD is associated with increases in HA and HA-associated ECM molecules. To test this hypothesis, we assessed HA accumulation and size; HA synthases (HAS) 1–3; and the HA-stabilizing hyaladherin, TSG-6 in parietal cortex samples from autopsied research subjects with not AD (CERAD = 0, Braak = 0–II, n = 12–21), intermediate AD (CERAD = 2, Braak = III–IV, n = 13–18), and high AD (CERAD = 3, Braak = V–VI, n = 32–40) AD neuropathologic change. By histochemistry, HA was associated with deposits of amyloid and tau, and was also found diffusely in brain parenchyma, with overall HA quantity (measured by ELSA) significantly greater in brains with high AD neuropathology. Mean HA MW was similar among the samples. HAS2 and TSG-6 mRNA expression, and TSG-6 protein levels were significantly increased in high AD and both molecules were present in vasculature, NeuN-positive neurons, and Iba1-positive microglia. These results did not change when accounting for gender, advanced age (>90 years versus
Alex M. Helman, Morgan Siever, Katie L. McCarty, Ira T. Lott, Eric Doran, Erin L. Abner, Frederick A. Schmitt, Elizabeth Head
Microbleeds and Cerebral Amyloid Angiopathy in the Brains of People with Down Syndrome with Alzheimer’s Disease
Abstract: Cerebrovascular pathology is a significant mediator in Alzheimer’s disease (AD) in the general population. In people with Down syndrome (DS), the contribution of vascular pathology to dementia may play a similar role in age of onset and/or the rate of progression of AD. In the current study, we explored the extent of microbleeds (MBs) and the link between cerebral amyloid angiopathy (CAA) and MBs in the frontal cortex (FCTX) and occipital cortex (OCTX) in an autopsy series from individuals with DS (<40 years), DS with AD pathology (DSAD), sporadic AD, and control cases (2-83 years). Sections were immunostained against Aβ1-40 and an adjacent section stained using Prussian blue for MBs. MBs were both counted and averaged in each case and CAA was scored based on previously published methods. MBs were more frequent in DS cases relative to controls but present to a similar extent as sporadic AD. This aligned with CAA scores, with more extensive CAA in DS relative to controls in both brain regions. CAA was also more frequent in DSAD cases relative to sporadic AD. We found CAA to be associated with MBs and that MBs increased with age in DS after 30 years of age in the OCTX and after 40 years of age in the FCTX. MB and CAA appear to be a significant contributors to the development of dementia in people with DS and are important targets for future clinical trials.
Simon Ducharme, Leora Pearl-Dowler, Flora Gossink, Jillian McCarthy, Jimmy Lai, Bradford C. Dickerson, Howard Chertkow, Lucile Rapin, Everard Vijverberg, Welmoed Krudop, Annemieke Dols, Yolande Pijnenburg
The Frontotemporal Dementia versus Primary Psychiatric Disorder (FTD versus PPD) Checklist: A Bedside Clinical Tool to Identify Behavioral Variant FTD in Patients with Late-Onset Behavioral Changes
Abstract: Background: Differentiating early behavioral variant frontotemporal dementia (bvFTD) and primary psychiatric disorders (PPD) is complex and biomarkers have limited accuracy, leading to inaccurate diagnoses. Objectives: Develop a simple bedside clinical tool to differentiate bvFTD from PPD. Methods: A checklist of clinical features differentiating bvFTD from PPD was developed based on literature and clinical experience. The checklist was filled prospectively for 29 consecutive patients (Montreal Neurological Hospital) with late-onset (≥ age 40) behavioral changes suggestive of bvFTD. The checklist was subsequently retrospectively completed on the baseline visit (N=137) of the Late-Onset Frontal Lobe study (Amsterdam). In both cohorts, patients were followed 2 years to establish a final best clinical diagnosis, categorizing patients into Probable FTD (N=46), Possible FTD (N=8), Other Cognitive Disorder (N=36), Other Neurological Disorder (N=10), or PPD (N=66). Results: All items distinguished the two groups except “duration more than 5 years”, which was removed to create a final 17-item version. Mean checklist scores were significantly different across all groups (Oneway ANOVA F(4,161)=27.462, p<0.001). The PPD group had lower scores than all other dementia categories, with the largest difference between Probable FTD (X̄=12.04) and PPD (X̄=7.48). A score ≥11 was found to be strongly indicative of bvFTD (specificity 93.9%, sensitivity 71.1%, PPV 89.2%). Scores ≤8 were strongly indicative of a PPD (specificity 91.3%, sensitivity 77.3%, PPV 92.7%). Patient with scores of 9-10 are considered indeterminate. Conclusions: Although further prospective validation is required, the “FTD vs PPD Checklist” could provide a simple tool to improve diagnostic accuracy, particularly in non-specialized settings.
Andrea R. Zammit, Graciela Muniz-Terrera, Mindy J. Katz, Charles B. Hall, Ali Ezzati, David A. Bennett, Richard B. Lipton
Subtypes Based on Neuropsychological Performance Predict Incident Dementia: Findings from the Rush Memory and Aging Project
Abstract: Background: In a previous report, we used latent class analysis (LCA) to identify natural subgroups of older adults in the Einstein Aging Study (EAS) based on neuropsychological performance. These subgroups differed in demographics, genetic profile, and prognosis. Herein, we assess the generalizability of these findings to an independent sample, the Rush Memory and Aging Project (MAP), which used an overlapping, but distinct neuropsychological battery. Objective: Our aim was to identify the association of natural subgroups based on neuropsychological performance in the MAP cohort with incident dementia and compare them with the associations identified in the EAS. Methods: MAP is a community-dwelling cohort of older adults living in the northeastern Illinois, Chicago. Latent class models were applied to baseline scores of 10 neuropsychological measures across 1,662 dementia-free MAP participants. Results were compared to prior findings from the EAS. Results: LCA resulted in a 5-class model: Mixed-Domain Impairment (n = 71, 4.3%), Memory-specific-Impairment (n = 274, 16.5%), Average (n = 767, 46.1%), Frontal Impairment (n = 222, 13.4%), and a class of Superior Cognition (n = 328, 19.7%). Similar to the EAS, the Mixed-Domain Impairment, the Memory-Specific Impairment, and the Frontal Impairment classes had higher risk of incident Alzheimer’s disease when compared to the Average class. By contrast, the Superior Cognition had a lower risk of Alzheimer’s disease when compared to the Average class. Conclusions: Natural cognitive subgroups in MAP are similar to those identified in EAS. These similarities, despite study differences in geography, sampling strategy, and cognitive tests, suggest that LCA is capable of identifying classes that are not limited to a single sample or a set of cognitive tests.
Meirong Yang*, Yan Wang*, Ge Liang, Zhendong Xu, Charleen T. Chu, Huafeng Wei *These authors contributed equally to this work.
Alzheimer’s Disease Preselinin-1 Mutation Sensitizes Neurons to Impaired Autophagy Flux and Propofol Neurotoxicity: Role of Calcium Dysregulation
Abstract: Background: Disruption of intracellular Ca2+ homeostasis and associated autophagy dysfunction contribute to neuropathology in Alzheimer’s disease (AD). Objective: To study the effects of propofol on cell viability via its effects on intracellular Ca2+ homeostasis, and the impact of autophagy, in a neuronal model of presenilin-mutated familial AD (FAD). Methods: We treated PC12 cells, stably transfected with either mutated presenilin-1 (L286V) or wild type (WT) controls, with propofol at different doses and durations, in the presence or absence of extracellular Ca2+, antagonists of inositol trisphosphate receptors (InsP3R, xestospongin C) and/or ryanodine receptors (RYR, dantrolene), or an inhibitor of autophagy flux (Bafilomycin). We determined cell viability, cytosolic Ca2+ concentrations ([Ca2+]c), vATPase protein expression, and lysosomal acidification. Results: The propofol dose- and time-dependently decreased cell viability significantly more in L286V than WT cells, especially at the pharmacological dose (>50 µM), and together with bafilomycin (40 nM). Clinically used concentrations of propofol (< 20 µM) tended to increase cell viability. Propofol significantly increased [Ca2+]c more in L286V than in WT cells, which was associated with decrease of vATPase expression and localization to the lysosome. Both toxicity and increased Ca2+ levels were ameliorated by inhibiting InsP3R/RYR. However, the combined inhibition of both receptors paradoxically increased [Ca2+]c, by inducing Ca2+ influx from the extracellular space, causing greater cytotoxicity. Conclusion: Impairment in autophagy function acts to deteriorate cell death induced by propofol in FAD neuronal cells. Cell death is ameliorated by either RYR or InsP3R antagonists on their own, but not when both are co-administered.
Sabrina Strobel, Edna Grünblatt, Helmut Heinsen, Peter Riederer, Thomas Espach, Michael Meder, Camelia-Maria Monoranu
Astrocyte- and Microglia-Specific Mitochondrial DNA Deletions Levels in Sporadic Alzheimer’s Disease
Abstract: Oxidative stress is implicated in the pathogenesis of neurodegenerative diseases, including sporadic Alzheimer’s disease (AD). Mitochondrial DNA (mtDNA) deletions are markers of oxidative damage with an age-dependent accumulation. In a previous study, we analyzed mtDNA levels in diverse neuronal cell types in order to unravel the impact of oxidative stress in brains of AD patients. The aim of this study was to identify possible correlations between mtDNA deletion levels of selected astrocytes and microglia from three brain regions with different vulnerability to AD pathology and different stages of disease compared to controls. Our results reflect a higher vulnerability of hippocampal astrocytes and microglia to oxidative stress compared to other brain regions, such as cerebellum and brain stem.
Gamze Guven, Başar Bilgic, Zeynep Tufekcioglu, Nihan Erginel Unaltuna, Hasmet Hanagasi, Hakan Gurvit, Andrew Singleton, John Hardy, Murat Emre, Cagri Gulec, Jose Bras, Rita Guerreiro*, Ebba Lohmann* (Handling Associate Editor: Alberto Lleó) *These authors contributed equally to this work.
Peripheral GRN mRNA and Serum Progranulin Levels as a Potential Indicator for Both the Presence of Splice Site Mutations and Individuals at Risk for Frontotemporal Dementia
Abstract: Progranulin (GRN) gene mutations are a major cause of frontotemporal dementia (FTD). Most mutations identified to date are null mutations, which are predicted to cause the pathology via haploinsufficiency. Decreased peripheral progranulin protein (PGRN) levels are associated with the presence of GRN null mutations and are accepted as reliable biomarkers. In this study, our aim was to test whether the presence of specific GRN splice site mutations (c.-8+2T>G and c.708+6_9del), could be predicted by peripheral mRNA or protein GRN levels, by studying affected and asymptomatic individuals from FTD families. We also tested four missense GRN variants to assess if altered GRN levels depended on the type of mutation. Our results confirmed a reduction in both mRNA and protein PGRN levels in the splice site mutation carriers, which is consistent with previous reports for null mutations. Our results also suggested that both decreased peripheral GRN mRNA and serum PGRN levels indicate the presence of pathogenic mutations in affected individuals, and identify the asymptomatic individuals at risk, without previous knowledge of genetic status. Both inferences suggest a potential use of peripheral GRN mRNA or serum PGRN levels as biomarkers for families with FTD.
Haibo Zhang*, Ding Wang*, Ping Gong, Aihua Lin, Yan Zhang, Richard D. Ye, Yang Yu (Handling Associate Editor: Chengxin Gong) *These authors contributed equally to this work.
Formyl Peptide Receptor 2 Deficiency Improves Cognition and Attenuates Tau Hyperphosphorylation and Astrogliosis in a Mouse Model of Alzheimer’s Disease
Abstract: Alzheimer’s disease (AD) is characterized by progressive loss of memory and other cognitive functions. Accumulation of amyloid-β (Aβ) and hyperphosphorylated tau are two major neuropathological features of AD. Formyl peptide receptor 2 (FPR2), contributing to innate immunity and inflammation, has been implicated in the uptake and clearance of Aβ. It remains unclear whether FPR2 affects cognition and tau phosphorylation. The effects of FPR2 in cognition and tau phosphorylation were examined using FPR2 knock-out (Fpr2-/-) mice receiving intracerebroventricular (ICV) injection of streptozotocin (STZ). The general behaviors and cognitive functions were evaluated using rotarod, open field test, and Morris water maze test. The alteration in tau hyperphosphorylation and activation of astrocytes were determined by using western blotting and/or immunofluorescence staining. ICV injection of STZ impaired spatial learning and memory of mice in Morris water maze. FPR2 deficiency improved spatial learning and memory of ICV-STZ mice. In the hippocampus and cortex of ICV-STZ mice, a marked increase was observed in tau phosphorylation at Ser199, Thr205, and Ser396 compared with ICV-saline control mice. However, FPR2 deficiency attenuated the hyperphosphorylation of tau at Ser199 and Ser396. In addition, the expression of GFAP was significantly increased in hippocampus and cortex of ICV-STZ mice. FPR2 deletion reduced the increase of GFAP expression induced by ICV injection of STZ. These results indicate that FPR2 deficiency is associate with improved cognition, reduced tau hyperphosphorylation, and activation of astrocytes in the mouse AD model tested. FPR2 may be a potential target in AD prevention and therapy.
Christopher G. Schwarz, Jeffrey L. Gunter, Val J. Lowe, Stephen Weigand, Prashanthi Vemuri, Matthew L. Senjem, Ronald C. Petersen, David S. Knopman, Clifford R. Jack, Jr
A Comparison of Partial Volume Correction Techniques for Measuring Change in Serial Amyloid PET SUVR
Abstract: Longitudinal PET studies in aging and Alzheimer’s disease populations rely on accurate and precise measurements of change over time from serial PET scans. Various methods for partial volume correction (PVC) are commonly applied to such studies, but existing comparisons and validations of these PVC methods have focused on cross-sectional measurements. Rate of change measurements inherently have smaller magnitudes than cross-sectional measurements, so levels of noise amplification due to PVC must be smaller, and it is necessary to re-evaluate methods in this context. Here we compare the relative precision in longitudinal measurements from serial amyloid PET scans when using geometric transfer matrix (GTM) PVC versus the traditional two-compartment (Meltzer-style), three-compartment (Müller-Gärtner-style), and no-PVC approaches. We used two independent implementations of standardized uptake value ratio (SUVR) measurement and PVC (one in-house pipeline based on SPM12 and ANTs, and one using FreeSurfer 6.0). For each approach, we also tested longitudinal-specific variants. Overall, we found that measurements using GTM PVC had significantly worse relative precision (unexplained within-subject variability ≈4-8%) than those using two-compartment, three-compartment, or no PVC (≈2-4%). Longitudinally-stabilized approaches did not improve these properties. This data suggests that GTM PVC methods may be less suitable than traditional approaches when measuring within-person change over time in longitudinal amyloid PET.
Lara Hvidsten, Knut Engedal, Geir Selbæk, Torgeir Bruun Wyller, Jūratė Šaltytė Benth, Hege Kersten
Quality of Life in People with Young-Onset Dementia: A Nordic Two-Year Observational Multicenter Study
Abstract: Background: Cross-sectional studies of quality of life (QOL) of people with young-onset dementia shows diverging results. Objective: To identify factors associated with QOL in people with young-onset Alzheimer’s (AD) and frontotemporal dementia (FTD) and explore development in QOL over a two-year period, including differences between the two subtypes. Methods: A two-year cohort study of 88 community-dwelling people with young-onset AD and FTD recruited from Nordic memory clinics. QOL was assessed using the proxy version of the Quality of Life – Alzheimer’s Disease questionnaire, dementia severity was rated with the Clinical Dementia Rating scale, depressive symptoms by the Cornell Scale for Depression in Dementia, awareness with the Reed anosognosia scale, and needs using the Camberwell Assessment of Needs in the Elderly questionnaire. Factors associated with QOL and development in QOL over time were explored with growth mixture model trajectories and mixed model analyses. Results: We identified two groups of people following trajectories with better (n = 35) versus poorer (n = 53) QOL. People with more depressive symptoms at baseline had higher odds of belonging to poorer QOL group, OR 1.2 (CI 1.1; 1.5, p = 0.011). Having Alzheimer’s disease was associated with significantly better QOL (p = 0.047 at baseline, p = 0.009 at T1 and p = 0.033 at T2). Increasing number of unmet needs was significantly associated with poorer QOL at baseline (p=0.007), but not later in follow-up. Conclusion: Early assessment and treatment based on dementia subtype, depression, and individual needs may enhance quality of life in young-onset dementia.
Hugo Lövheim, Tove Norman, Bodil Weidung, Jan Olsson, Maria Josefsson, Rolf Adolfsson, Lars Nyberg, Fredrik Elgh
Herpes Simplex Virus, APOE ε4, and Cognitive Decline in Old Age: Results from the Betula Cohort Study
Abstract: Background: Herpes simplex virus (HSV) has been suggested to play a role in Alzheimer’s disease (AD) development. Objective: The aim of the present study was to investigate the early AD-related symptom episodic memory decline in relation to HSV and carriage of allele 4 of the apolipoprotein E gene (APOE ε4) in a large population-based cohort with a long follow-up time. Methods: The study included 3,413 persons, with longitudinal data available for 1,293 persons with a mean follow-up time of 11.6 years. The associations between HSV carriage, APOE ε4 carriage, and episodic memory was investigated at baseline, as well as in longitudinal analyses where individuals with and without HSV antibodies (HSV1/2 non-specific) were matched and episodic memory decline compared. Results: Cross-sectional analyses revealed an age-dependent association of HSV carriage with lower episodic memory function, particularly among APOE ε4 carriers (p = 0.008). Longitudinal analyses showed an increased risk of episodic memory decline in HSV carriers (≥ 65 years: p < 0.001, all ages: non-significant), and a significant interaction between HSV and APOE ε4 for episodic memory decline (p < 0.001). Conclusion: In this large population-based cohort study, both cross-sectional and longitudinal results support an association between HSV carriage and declining episodic memory function, especially among APOE ε4 carriers. The results strengthen the hypothesis that HSV is associated with AD development.
Xue-Jie Wang, Wei Xu, Jie-Qiong Li, Xi-Peng Cao, Lan Tan, Jin-Tai Yu (Handling Associate Editor: Ling-Qiang Zhu)
Early-Life Risk Factors for Dementia and Cognitive Impairment in Later Life: A Systematic Review and Meta-Analysis
Abstract: Background: Early-life environment is related to childhood brain development and cognitive function in later life. However, the associations of early-life risk factors with dementia and cognitive impairment were still controversial. Objective: Our study aims to investigate early-life risk factors for dementia and cognitive impairment. Methods: PubMed and Cochrane Library were searched to identify prospective cohort and retrospective case-control studies exploring early-life factors for dementia and cognitive impairment. Pooled effect estimates for each factor were calculated by random-effect model. Results: Thirty-seven studies with 46,727 participants were included. The pooled results indicated significant associations of dementia with food deficiency (OR= 2.05, 95% CI= 1. 22-3.44), low education level (RR= 1.80, 95% CI= 1.60-2.02), and shorter leg length (OR= 1.19, 95% CI= 1.07-1.32). Other potential risk factors identified in the systematic review include rural residence, number of siblings, history of head trauma, early parental death or re-marriage, and poor learning ability. Conclusion: Early-life factors, including education level, leg length, history of childhood head trauma, family-related factors and learning ability, were associated with the risk of dementia and cognitive impairment in later life. Further high-quality longitudinal studies are needed to verify the causality between early-life risk factors and dementia and cognitive impairment.
Fadia El Bitar, Najeeb Qadi, Saad Al Rajeh, Amna Majrashi, Sara Abdulaziz, Nada Majrashi, Maznah Al Inizi, Asma Taher, Nada Al Tassan (Handling Associate Editor: Amalia C. Bruni)
Genetic Study of Alzheimer’s Disease in Saudi Population
Abstract: Background: Alzheimer’s disease (AD) is a chronic neurological disorder associated with mental decline and dementia. Several studies focused on investigating the molecular basis of the disease that led to the identification of several causative genes and risk associated alleles. Replication of these studies and findings from different populations is very important. Objective: Molecular assessment of a cohort of 117 familial and sporadic AD cases from Saudi Arabia. Methods: Comprehensive screening for point mutations was carried out by direct sequencing of coding regions in the three known AD causative genes: PSEN1, PSEN2, APP, as well as the AD associated gene SORL1. All patients were also genotyped for APOE alleles. In silico 3D protein structure analysis was performed for two novel SORL1 variants. Results: We identified a total of eight potential pathogenic missense variants in all studied genes. Five of these variants were not previously reported including four in SORL1 (p.Val297Met, p.Arg1084Cys, p.Asp1100Asn, and p.Pro1213Ser) and one in APP (p.Glu380Lys). The frequency of APOE-ε4 allele was 21.37% of total investigated cases. In silico 3D protein structure analysis of two SORL1 novel missense variants (p.Pro1213Ser and p.Arg1084Cys) suggested that these variants may affect the folding of the proteins and disturb their structure. Conclusions: Our comprehensive analysis of the open reading frame of the known genes have identified potential pathogenic rare variants in 18/117 cases. We found the point mutations in AD main genes (PSEN1, PSEN2, and APP) were underrepresented in our cohort of patients. Our results confirm involvement of SORL1 in familial and sporadic AD cases.
Cristian Bonvicini*, Catia Scassellati*, Luisa Benussi, Emilio Di Maria, Carlo Maj, Miriam Ciani, Silvia Fostinelli, Anna Mega, Martina Bocchetta, Gaetana Lanzi, Edoardo Giacopuzzi, Sergio Ferraboli, Michela Pievani, Virginia Fedi, Carlo Alberto Defanti, Silvia Giliani, Alzheimer’s Disease Neuroimaging Initiative, Giovanni Battista Frisoni, Roberta Ghidoni, Massimo Gennarelli (Handling Associate Editor: Stefan Teipel) *These authors contributed equally to this work.
Next Generation Sequencing Analysis in Early Onset Dementia Patients
Abstract: Background: Early onset dementias (EOD) are rare neurodegenerative dementias that present before 65 years. Genetic factors have a substantially higher pathogenetic contribution in EOD patients than in late onset dementia. Objective: To identify known and/or novel rare variants in major candidate genes associated to EOD by high-throughput sequencing. Common-risk variants of apolipoprotein E (APOE) and prion protein (PRNP) genes were also assessed. Methods: We studied 22 EOD patients recruited in Memory Clinics, in the context of studies investigating genetic forms of dementia. Two methodological approaches were applied for the target-Next Generation Sequencing (NGS) analysis of these patients. In addition, we performed progranulin plasma dosage, C9Orf72 hexanucleotide repeat expansion analysis, and APOE genotyping. Results: We detected three rare known pathogenic mutations in the GRN and PSEN2 genes and eleven unknown-impact mutations in the GRN, VCP, MAPT, FUS, TREM2, and NOTCH3 genes. Six patients were carriers of only common risk variants (APOE and PRNP), and one did not show any risk mutation/variant. Overall, 69% (n=9) of our early onset Alzheimer’s disease (EAOD) patients, compared with 34% (n=13) of sporadic late onset Alzheimer’s disease (LOAD) patients and 27% (n=73) of non-affected controls (ADNI, whole genome data), were carriers of at least two rare/common risk variants in the analyzed candidate genes panel, excluding the full penetrant mutations. Conclusion: This study suggests that EOD patients without full penetrant mutations are characterized by higher probability to carry polygenic risk alleles that patients with LOAD forms. This finding is in line with recently reported evidence, thus suggesting that the genetic risk factors identified in LOAD might modulate the risk also in EOAD.
Makoto Ishii, Hooman Kamel, Costantino Iadecola (Handling Associate Editor: Michelle Mielke))
Retinol Binding Protein 4 Levels Are Not Altered in Preclinical Alzheimer’s Disease and Not Associated with Cognitive Decline or Incident Dementia
Abstract: Accumulating evidence suggests that disparate pathways from systemic metabolism to retinoic acid/vitamin A signaling can contribute to Alzheimer’s disease (AD) pathobiology. Retinol binding protein 4 (RBP4) is an adipocyte-secreted hormone (adipokine) that regulates insulin signaling and is also a key transporter of retinoic acid and its derivatives. While earlier studies found alterations in the brain and cerebrospinal fluid (CSF) levels of RBP4 in later stages of AD, it is not known if circulating RBP4 is altered in preclinical AD or if it can be a useful biomarker for cognitive decline and dementia. In this study, we used ELISA to measure plasma RBP4 levels in cognitively normal individuals (Clinical Dementia Rating, CDR 0). Subjects with preclinical AD were identified by previously established CSF criteria (preclinical AD: 20 men, 18 women; control: 45 men, 73 women). Plasma RBP4 levels were similar between preclinical AD and control subjects in men (preclinical AD: 30.0 ± 7.4 μg/mL; control: 30.0 ± 8.7 μg/mL; p = 0.97) and women (preclinical AD 30.9 ± 7.9 μg/mL; control: 31.7 ± 8.5 μg/mL; p = 0.72). Additionally, RBP4 levels were not related to body mass index or CSF AD biomarkers levels of amyloid-β42, tau, or phosphorylated tau. Baseline plasma RBP4 levels were not associated with the incidence of CDR ≥ 0.5, all-cause dementia, or AD diagnosis. Collectively, these results do not support peripheral RBP4 as a clinical biomarker or therapeutic target in the early stages of AD.
Eduardo Torrealba, Pilar Garcia-Morales, Juan Carlos Cejudo, Mario Diaz, Francisco Rodriguez-Esparragon, Oscar Fabre, Fatima Mesa-Herrera, Raquel Marin, Florentino Sanchez-Garcia, Aurelio Rodriguez-Perez, Nina Gramunt
In-Out-Test: A New Paradigm for Sorting the Wheat from the Chaff in Prodromal Alzheimer’s Disease
Abstract: Background: Assessment of hippocampal amnesia is helpful to distinguish between normal cognition and mild cognitive impairment (MCI), but not for identifying converters to dementia. Here biomarkers are useful but novel neuropsychological approaches are needed in their absence. The In-out-test assesses episodic memory using a new paradigm hypothesized to avoid reliance on executive function, which may compensate for damaged memory networks. Objective: To assess the validity of the In-out-test in identifying prodromal Alzheimer’s disease (PAD) in a clinical setting, by comparing this to the Free and Cued Selective Reminding Test (FCSRT) and cerebrospinal fluid biomarkers. Methods: A cross-sectional study of 32 cognitively healthy, 32 MCI, and 30 progressive dementia subjects. All participants were given both the In-out-test and the FCSRT; 40 of them also received a lumbar puncture. Results: Internal consistency was demonstrated using Cronbach Alpha (r= 0.81) and Inter-rater reliability with Kappa (k=0.94). Intraclass correlation (ICC) for test-retest reliability: r=0.57 (p= 0.57). ICC between the In-out-test and FCSRT r= 0.87 (p=0.001). ICC between the In-out-test and Aβ42 and P-tau/Aβ42 for controls: 0.73 and 0.75, respectively; P-tau for MCI: 0.77 and total sample: 0.70; Aβ42 for dementia: 0.71. All ICC measures between FCSRT and biomarkers were ≤ 0.264. AD diagnosis: In-out-test k=0.71; FCSRT k= 0.49. PAD diagnosis (N=35): In-out-test k=0.69; FCSRT k= 0.44. Conclusions: The In-out-test detected prodromal AD with a higher degree of accuracy than a conventional hippocampal-based memory test. These results suggest that this new paradigm could be of value in clinical settings, predicting which patients with MCI will go on to develop AD.
Simin Mahinrad, Ian Ferguson, Peter W. Macfarlane, Elaine N. Clark, David J. Stott, Ian Ford, Simon P. Mooijaart, Stella Trompet, Diana van Heemst, J. Wouter Jukema, Behnam Sabayan (Handling Associate Editor: M. Arfan Ikram)
Spatial QRS-T Angle and Cognitive Decline in Older Subjects
Abstract: Background: An abnormally wide spatial QRS-T angle on an ECG is a marker of heterogeneity in electrical activity of cardiac ventricles and is linked with cardiovascular events. Growing evidence suggests that cardiac dysfunction might signal future cognitive decline. Objective: In this study, we investigated whether spatial QRS-T angle associates with future cognitive decline in older subjects at high cardiovascular risk. Methods: We included 4,172 men and women (mean age 75.2 ± 3.3 years) free of cardiac arrhythmias from the PROSPER cohort. Spatial QRS-T angle was calculated from baseline 12-lead ECGs using a matrix transformation method. Cognitive function was assessed using 4 neuropsychological tests including Stroop test, letter-digit coding test, immediate and delayed picture word learning tests. Cognitive function was assessed at baseline and repeatedly during a mean follow-up time of 3.2 years. Using linear mixed models, we calculated the annual changes of cognitive scores in sex-specific thirds of spatial QRS-T angle. Results: Participants with wider spatial QRS-T angle had a steeper decline in letter-digit coding test (β=-0.0106, p=0.004), immediate picture-word learning test (β=-0.0049, p=0.001), and delayed picture-word learning test (β=-0.0055, p=0.013). All associations were independent of arrhythmias, cardiovascular risk factors, comorbidities, medication use, cardiovascular events, and other ECG abnormalities including QRS duration, QTc interval, T wave abnormalities, and left ventricular hypertrophy. Conclusion: Abnormal cardiac electrical activity characterized by wide spatial QRS-T angle associates with accelerated cognitive decline independent of conventional cardiovascular factors. These findings suggest a link between a non-traditional ECG measure of pre-clinical cardiac pathology and future cognitive decline.
Gali H. Weissberger, Tamar H. Gollan, Mark W. Bondi, Daniel A. Nation, Lawrence A. Hansen, Douglas Galasko, David P. Salmon
Neuropsychological Deficit Profiles, Vascular Risk Factors, and Neuropathological Findings in Hispanic Older Adults with Autopsy-Confirmed Alzheimer’s Disease
Abstract: This study aimed to determine if patterns of neuropsychological deficits, vascular risk factors, and neuropathology differ in Hispanic and Non-Hispanic patients with autopsy-confirmed Alzheimer’s disease (AD). Participants were enrolled in a longitudinal study at the Shiley-Marcos AD Research Center at the University of California, San Diego. Hispanic (n=14) and Non-Hispanic (n=20) patients with autopsy-confirmed AD who scored ≥95 on the Dementia Rating Scale (DRS) were included. Patient groups were matched on age, education, global mental status, and severity of functional decline; they were compared to Hispanic (n=14) or Non-Hispanic (n=20) cognitively-normal controls of similar age and education. Ethnicity (Hispanic, Non-Hispanic) by disease state (autopsy-confirmed AD or cognitively normal) comparisons were made for cognitive test performance and vascular risk factors. Patient groups were further compared on measures of AD (Braak stage, neuritic plaques, neurofibrillary tangles), vascular neuropathology, and performance across cognitive domains of memory, language, attention, executive functions, and visuospatial abilities after scores were z-transformed based on respective culturally-appropriate control groups. Patient groups had similar overall AD pathology burden, whereas Hispanics with AD had more small parenchymal arteriolar disease and amyloid angiopathy than Non-Hispanics with AD. Despite largely similar pathology, Hispanics with AD were less cognitively impaired (relative to respective NC groups) than Non-Hispanics with AD, and exhibited a different pattern of deficits across cognitive domains. Findings suggest that cognitive deficits that are usually prominent in AD may be less salient in Hispanic patients and this may adversely impact the ability to clinically detect the disease in mild to moderate stages.
Lutz Frölich, Alireza Atri, Clive Ballard, Pierre N. Tariot, José Luis Molinuevo, Neli Boneva, Marie A. Geist, Lars L. Raket, Jeffrey L. Cummings (Handling Associate Editor: Patrizia Mecocci)
Open-Label, Multicenter, Phase III Extension Study of Idalopirdine as Adjunctive to Donepezil for the Treatment of Mild-Moderate Alzheimer’s Disease
Abstract: This open-label extension study evaluated the long-term safety and tolerability of idalopirdine 60 mg/day as adjunctive therapy in patients with mild-moderate Alzheimer’s disease (AD). This extension study was a continuation of Studies 1 and 2 of the Phase III development program for idalopirdine and comprised a 28-week open-label treatment period (“OLEX”) and a subsequent 24-week open-label treatment period with memantine (“MEMOLEX”) in selected patients. The previous studies had shown no evidence of efficacy with idalopirdine as adjunctive treatment to donepezil but with good tolerability (of 1,791 patients randomized, 1,609 [90%] completed the double-blind studies). Of those, 1,463 patients (91%) entered the open-label extension study. During the 28-week OLEX period, the percentage of patients having treatment-emergent adverse events (TEAEs) ranged between 51% and 59% across the treatment groups originating from the lead-in studies. During the subsequent 24-week MEMOLEX period, 51% of the patients had TEAEs. Increases in liver enzymes (occurring in 1-3% of trial participants) were transient and no new safety signals were observed with longer term exposure. No consistent effects demonstrating benefits with idalopirdine were observed on efficacy parameters when patients transitioned to 60 mg in the extension study. Overall, idalopirdine was safe and well tolerated when added to donepezil, and when memantine was added to a prior combination of idalopirdine and donepezil. There were no new safety signals observed with up to 18 months of exposure at the described doses to idalopirdine.
Kuan-Yu Pan, Weili Xu, Francesca Mangialasche, Serhiy Dekhtyar, Laura Fratiglioni, Hui-Xin Wang
Working Life Psychosocial Conditions in Relation to Late-Life Cognitive Decline: A Population-Based Cohort Study
Abstract: While the importance of working conditions on cognitive function has been tentatively suggested previously, few studies have considered cumulative effects of exposure throughout the working life. We examined the association between job demand-control status and late-life cognitive decline, taking into account exposure durations. In the population-based cohort study, Swedish National Study on Aging and Care-Kungsholmen, 2,873 dementia-free participants aged 60+ were followed up to nine years. Cognitive function was measured using the Mini-Mental State Examination. The entire working life was outlined through interview and occupations were graded with a psychosocial job-exposure matrix. Multivariate linear mixed-effects models were used. Slower cognitive decline was observed among people with high job control (β: 0.10, 95% CI: 0.03, 0.19) and demands (β: 0.15, 95% CI: 0.07, 0.22) in the longest-held job. Compared to active job, faster decline was shown in low strain (β: -0.17, 95% CI: -0.26, -0.08), high strain (β: -0.13, 95% CI: -0.24, -0.03), and passive job (β: -0.22, 95% CI: -0.34, -0.11). Longer duration of active jobs was associated with slower cognitive decline (β: 0.24, 95% CI: 0.16, 0.32), whereas faster decline was associated with longer durations of low strain (β: -0.12, 95% CI: -0.19, -0.05), high strain (β: -0.13, 95% CI: -0.21, -0.04), and passive jobs (β: -0.12, 95% CI: -0.20, -0.04). In conclusion, not only psychologically stressful jobs, but also low-stimulating and passive jobs are associated with faster cognitive decline in later life. Duration of exposure may play a role in the psychosocial working condition-cognitive decline association.
M. Florencia Iulita*, Aravind Ganesh*, Rowan Pentz, Lisi Flores Aguilar, Palma Gubert, Adriana Ducatenzeiler, Sharon Christie, Gordon K. Wilcock, A. Claudio Cuello *These authors contributed equally to this work.
Identification and Preliminary Validation of a Plasma Profile associated with Cognitive Decline in Dementia and At-Risk Individuals: A Retrospective Cohort Analysis
Abstract: Biomarker discovery is a major need for earlier dementia diagnosis. We evaluated a plasma signature of amyloid, metallo-proteinases (MMPs), and inflammatory markers in a cohort of at-risk individuals and individuals clinically diagnosed with probable Alzheimer’s disease (pAD). Using multiplex arrays, we measured Aβ40, Aβ42, MMP-1, MMP-3, MMP-9, IFN-γ, TNF-α, IL-6, IL-8, and IL-10 in plasma from 107 individuals followed every 6 months for 3 years. Final diagnoses included: pAD (n=28), mild cognitive impairment (MCI, n=30), subjective memory impairment (SMI, n=30), and asymptomatic (NCI, n=19). Blood was drawn at final follow-up. We used linear and logistic regressions to examine biomarker associations with prior known decline on the Montreal Cognitive Assessment (MoCA) and the Cambridge Cognitive Examination (CAMCOG); as well disease progression by the time of blood-draw. We derived a biomarker composite from the individual markers, and tested its association with a clinical diagnosis of pAD. Lower Aβ40 and Aβ42 and higher IL-8, IL-10, and TNF-α were associated with greater cognitive decline per the MoCA and CAMCOG. MMP-3 was higher in SMI, MCI, and pAD than NCI. Whereas the other investigative molecules did not differ between groups, composite scores created using MoCA/CAMCOG-based trends in Aβ40, Aβ42, MMP-1, MMP-3, IL-8, IL-10, and TNF-α were associated with a final diagnosis of pAD (c-statistic 0.732 versus 0.602 for age-sex alone). Thus, plasma amyloid, MMP, and inflammatory biomarkers demonstrated differences in individuals with cognitive deterioration and/or progression to MCI/pAD. Our findings support studying these markers earlier in the continuum of probable AD as well as in specific dementias.
Javiera Gavilan, Daniela Mennickent, Oscar Ramirez-Molina, Sergio Triviño, Claudia Perez, Tiare Silva-Grecchi, Pamela Godoy, Jose Becerra, Luis G. Aguayo, Gustavo Moraga-Cid, Victoria San Martin, Gonzalo E. Yevenes, Patricio A. Castro, Leonardo Guzman, Jorge Fuentealba
17-Oxo-Sparteine and Lupanine, Obtained from Cytisus scoparius, Exert a Neuroprotection against Soluble Oligomers of Amyloid-β Toxicity by Nicotinic Acetylcholine Receptors
Abstract: Alzheimer’s disease (AD) is a neurodegenerative pathology, which is characterized by progressive and irreversible cognitive impairment. Most of the neuronal perturbations described in AD can be associated with soluble amyloid-β oligomers (SO-Aβ). There is a large amount of evidence demonstrating the neuroprotective effect of Nicotine neurotransmission in AD, mainly through nicotinic acetylcholine receptor (nAChR) activation and antiapoptotic PI3K/Akt/Bcl-2 pathway signaling. Using HPLC and GC/MS, we isolated and characterized two alkaloids obtained from C. scoparius, Lupanine (Lup), and 17-oxo-sparteine (17-ox), and examined their neuroprotective properties in a cellular model of SO-Aβ toxicity. Our results showed that Lup and 17-ox (both at 0.03 μM) prevented SO-Aβ-induced toxicity in PC12 cells (Lup: 64±7%; 17-ox: 57±6%). Similar results were seen in hippocampal neurons where these alkaloids prevented SO-Aβ neurotoxicity (Lup: 57±2%; 17-ox: 52±3%) and increased the frequency of spontaneous calcium transients (Lup: 60 ± 4%; 17-Ox: 40 ± 3%), suggesting an enhancing effect on neural network activity and synaptic activity potentiation. All of the neuroprotective effects elicited by both alkaloids were completely blocked by α-bungarotoxin. Additionally, we observed that the presence of both Lup and 17-ox increased Akt phosphorylation levels (52±4% and 35±7%, respectively) in cells treated with SO-Aβ (3 h). Taken together, our results suggest that the activation of nAChR by Lup and 17-ox induces neuroprotection in different cellular models, and appears to be an interesting target for the development of new pharmacological tools and strategies against AD.
Mei Xu, Lin Zhang, Ning Jiang, Wenxia Zhou, Yongxiang Zhang
Pathological Changes in Alzheimer’s Disease Analyzed Using Induced Pluripotent Stem Cell-Derived Human Microglia-Like Cells
Abstract: Microglia constitute the majority of innate immune cells in the brain, and their dysfunction is associated various central nervous system diseases. Human microglia are extremely difficult to obtain experimentally, thereby limiting studies on their role in complex diseases. Microglia derived from human stem cells provide new tools to assess the pathogenesis of complex diseases and to develop effective treatment methods. This study aimed to develop a reliable method to derive human microglial-like cells (iMGLs) from induced pluripotent stem cells (iPSCs) expressing microglia-specific markers IBA1 and TMEM119 and respond to lipopolysaccharide (LPS) stimulation. Thereafter, we compared iMGL functions from Alzheimer's disease (AD) patients and cognitive normal controls (CNCs). AD-iMGLs displayed stronger phagocytic ability with or without stimulation. High LPS concentrations (>2 μg/ml) caused death in CNC-iMGLs, while AD-iMGLs did not display significant cell death. Cytokine analysis revealed that TNF-α, IL-6, and IL-10 secreted by AD-iMGLs were significantly increased upon LPS stimulation compared to those in CNC-iMGLs. The present results indicate that AD-iMGLs exhibit significant inflammatory characteristics and can reflect some pathological changes in microglia in AD, thereby providing new valuable tools to screen candidate drugs for AD and to elucidate the mechanisms underlying AD pathogenesis.
Sabrina Islamoska, Kazi Ishtiak-Ahmed, Åse Marie Hansen, Matias Brødsgaard Grynderup, Erik Lykke Mortensen, Anne Helene Garde, Finn Gyntelberg, Eva Irene Bossano Prescott, Eszter Török, Gunhild Waldemar, Kirsten Nabe-Nielsen (Handling Associate Editor: Shireen Sindi)
Vital Exhaustion and Incidence of Dementia: Results from the Copenhagen City Heart Study
Abstract: Background: Psychological distress is potentially linked to the risk of dementia through neurologic and cardiovascular mechanisms. Vital exhaustion (VE) is a mental state of psychological distress, which could be a risk factor for dementia. Objective: To investigate whether VE is a risk factor for dementia in later life. Methods: We used data from 6,807 participants attending the third survey of the Copenhagen City Heart Study in 1991-1994. VE was assessed by 17 symptoms (score: 0-17) from the Maastricht Questionnaire. Information on dementia was obtained from national registers. Risk time for dementia was counted from five years after VE assessment for participants >55 years at the time of VE assessment. For younger participants, risk time for dementia was counted from the year they turned 60 years and onwards. Participants were followed until 2016. We used Poisson regression to calculate incidence rate ratios (IRR) and their 95% confidence intervals (CI). Results: During an average follow-up of 10 years, 872 participants were registered with dementia. We found a dose-response relation between the number of VE symptoms and the incidence of dementia. For every additional VE symptom, the dementia incidence increased by 2% (IRR = 1.024; 95% CI: 1.004-1.043). Adjustment for socio-demographic and health-related factors did not change the results substantially. Neither did stratification by age, sex, educational level, and marital status. Conclusion: We found evidence that VE is a risk factor for dementia. Our sensitivity analyses supported that this association was not only due to VE being a potential prodromal sign of dementia.
Carolina Delgado, Rodrigo C. Vergara, Melissa Martínez, Gada Musa, Fernando Henríquez, Andrea Slachevsky (Handling Associate Editor: Krista Lanctôt)
Neuropsychiatric Symptoms in Alzheimer’s Disease Are the Main Determinants of Functional Impairment in Advanced Everyday Activities
Abstract: Background: Neuropsychiatric symptoms and cognitive impairment are independent contributors of functional impairment in activities of daily living (ADL) in Alzheimer’s disease (AD) patients. ADL could be divided according to its complexity in three subdomains: basic (BADL), instrumental (IADL), and advanced (a-ADL). Objective: Studying the cognitive and neuropsychiatric determinants of BADL, IADL, and a-ADL in normal cognitive elders and AD patients. Methods: 144 subjects were graduated using the clinical dementia rating (CDR) in CDR=0, n=52 (control group) and 92 AD patients CDR=0.5, n=34 and CDR=1&2, n=58. They were assessed with measures of cognitive performance and neuropsychiatric symptoms that were included in regression models to measure the best predictors for each ADL subdomain at every CDR status. Results: AD patients were significantly older, and had significantly more severe functional impairment, neuropsychiatric symptoms, and cognitive decline than controls. The best predictors of functional impairment in controls and CDR=0.5 AD patients were neuropsychiatric symptoms; in the CDR 0.5 patients, apathy severity was the most important determinant of IADL and a-ADL impairment. While in the CDR 1&2 AD patients, cognitive impairment was the principal determinant of functional impairment, being memory the best determinant of IADL and a-ADL impairment, while global cognition was of BADL impairment. Conclusions: The contribution of cognitive impairment and neuropsychiatric symptoms varied according to the subdomain of ADL, and the CDR. In very mild AD and controls the neuropsychiatric symptoms are the best predictors of more complex ADL impairment, while cognitive impairment is more important at mild to moderate states of AD.
Liang Hui, Mahmoud L. Soliman, Nicholas H. Geiger, Nicole M. Miller, Zahra Afghah, Koffi L. Lakpa, Xuesong Chen*, Jonathan D. Geiger
Acidifying Endolysosomes Prevented Low-Density Lipoprotein-Induced Amyloidogenesis
Abstract: Cholesterol dyshomeostasis has been linked to the pathogenesis of sporadic Alzheimer’s disease (AD). In furthering the understanding of mechanisms by which increased levels of circulating cholesterol augments the risk of developing sporadic AD, others and we have reported that low-density lipoprotein (LDL) enters brain parenchyma by disrupting the blood-brain barrier and that endolysosome de-acidification plays a role in LDL-induced amyloidogenesis in neurons. Here, we tested the hypothesis that endolysosome de-acidification was central to amyloid-β (Aβ) generation and that acidifying endolysosomes protects against LDL-induced increases in Aβ levels in neurons. We demonstrated that LDL, but not HDL, de-acidified endolysosomes and increased intraneuronal and secreted levels of Aβ. ML-SA1, an agonist of endolysosome-resident TRPML1 channels, acidified endolysosomes, and TRPML1 knockdown attenuated ML-SA1-induced endolysosome acidification. ML-SA1 blocked LDL-induced increases in intraneuronal and secreted levels of Aβ as well as Aβ accumulation in endolysosomes, prevented BACE1 accumulation in endolysosomes, and decreased BACE1 activity levels. LDL downregulated TRPML1 protein levels, and TRPML1 knockdown worsens LDL-induced increases in Aβ. Our findings suggest that endolysosome acidification by activating TRPML1 may represent a protective strategy against sporadic AD.
Michael Malek-Ahmadi, Kewei Chen, Sylvia E. Perez, Elliott J. Mufson
Cerebral Amyloid Angiopathy and Neuritic Plaque Pathology Correlate with Cognitive Decline in Elderly Non-Demented Individuals
Abstract: Background: Cerebral amyloid angiopathy (CAA) is a vascular neuropathology commonly reported in non-cognitively impaired (NCI), mild cognitive impairment, and Alzheimer’s disease (AD) brains. However, it is unknown whether similar findings are present in non-demented elderly subjects. Objective: This study determined the association between CAA and cognition among elderly NCI subjects with varying levels of AD pathology. Methods: Data from 182 cases that received a diagnosis of NCI at their first clinical assessment were obtained from the Rush Religious Orders study (RROS). A cognitive composite score was used to measure cognitive decline. CAA was dichotomized as present or absent. Cases were also dichotomized according to CERAD neuropathological diagnosis and Braak staging. A mixed model-repeated measures analysis assessed decline on the cognitive composite score. Results: CAA, alone, was not associated with cognitive decline [-0.87 (95% CI: -3.33, 1.58), p = 0.49]. However, among those with CAA, the High CERAD group had significantly greater decline relative to the Low CERAD group [-4.08 (95% CI: -7.10, -1.06), p = 0.008]. The High and Low CERAD groups were not significantly different [-1.77 (95% CI: -6.14, 2.60), p = 0.43] in those without CAA. Composite score decline in the High and Low Braak groups with [-1.32 (95% CI: -4.40, 1.75), p = 0.40] or without [0.27 (95% CI: -4.01, 4.56), p = 0.90] CAA was not significantly different. Conclusion: The current data shows that an interaction between CAA and plaque load is associated with greater decline on a cognitive composite score used to test non-cognitively impaired elderly participants in AD prevention trials.