Publications by authors named "Julie A Schneider"

367 Publications

Analysis of genes (TMEM106B, GRN, ABCC9, KCNMB2, and APOE) implicated in risk for LATE-NC and hippocampal sclerosis provides pathogenetic insights: a retrospective genetic association study.

Acta Neuropathol Commun 2021 09 15;9(1):152. Epub 2021 Sep 15.

Department of Biostatistics, College of Public Health, University of Kentucky, 201 Multidisciplinary Science Building, 725 Rose Street, Lexington, KY, 40536-0082, USA.

Limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) is the most prevalent subtype of TDP-43 proteinopathy, affecting up to 1/3rd of aged persons. LATE-NC often co-occurs with hippocampal sclerosis (HS) pathology. It is currently unknown why some individuals with LATE-NC develop HS while others do not, but genetics may play a role. Previous studies found associations between LATE-NC phenotypes and specific genes: TMEM106B, GRN, ABCC9, KCNMB2, and APOE. Data from research participants with genomic and autopsy measures from the National Alzheimer's Coordinating Center (NACC; n = 631 subjects included) and the Religious Orders Study and Memory and the Rush Aging Project (ROSMAP; n = 780 included) were analyzed in the current study. Our goals were to reevaluate disease-associated genetic variants using newly collected data and to query whether the specific genotype/phenotype associations could provide new insights into disease-driving pathways. Research subjects included in prior LATE/HS genome-wide association studies (GWAS) were excluded. Single nucleotide variants (SNVs) within 10 kb of TMEM106B, GRN, ABCC9, KCNMB2, and APOE were tested for association with HS and LATE-NC, and separately for Alzheimer's pathologies, i.e. amyloid plaques and neurofibrillary tangles. Significantly associated SNVs were identified. When results were meta-analyzed, TMEM106B, GRN, and APOE had significant gene-based associations with both LATE and HS, whereas ABCC9 had significant associations with HS only. In a sensitivity analysis limited to LATE-NC + cases, ABCC9 variants were again associated with HS. By contrast, the associations of TMEM106B, GRN, and APOE with HS were attenuated when adjusting for TDP-43 proteinopathy, indicating that these genes may be associated primarily with TDP-43 proteinopathy. None of these genes except APOE appeared to be associated with Alzheimer's-type pathology. In summary, using data not included in prior studies of LATE or HS genomics, we replicated several previously reported gene-based associations and found novel evidence that specific risk alleles can differentially affect LATE-NC and HS.
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http://dx.doi.org/10.1186/s40478-021-01250-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8442328PMC
September 2021

Association of Amyloid-β Pathology with Decision Making and Scam Susceptibility.

J Alzheimers Dis 2021 ;83(2):879-887

Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, USA.

Background: Recent findings suggest that poor decision making and increased scam susceptibility are harbingers of Alzheimer's disease (AD) dementia and may be among the earliest behavioral manifestations of pathologic cognitive aging. However, the degree to which poor decision making and scam susceptibility reflect accumulating Alzheimer's disease (AD) pathology remains unclear.

Objective: To investigate the associations of AD pathology with decision making and scam susceptibility in older adults without dementia.

Methods: Data came from 198 deceased participants without clinical dementia (mean age at death = 90 years; 69%women) from two ongoing studies of aging. All underwent annual clinical evaluations, completed assessments of healthcare and financial decision making and scam susceptibility, and brain donation. Neuropathologic evaluations quantified pathologic hallmarks of AD, amyloid-β and tau-tangles, Lewy body pathology, and TDP-43 proteinopathy.

Results: In linear regression models adjusted for demographics, amyloid-β pathology was associated with lower decision making (estimate = -0.35; SE = 0.16, p = 0.03), particularly healthcare decision making (estimate = -0.20; SE = 0.09, p = 0.03), as well as greater scam susceptibility (estimate = 0.12; SE = 0.04, p = 0.003); tau-tangle pathology was not related. Further, TDP-43 pathology was associated with greater scam susceptibility (estimate = 0.10; SE = 0.04; p = 0.02).

Conclusion: Accumulating AD pathology, particularly amyloid-β, is associated with poor decision making and increased scam susceptibility among older persons without overt cognitive impairment. These findings provide compelling evidence that decision making and scam susceptibility are sensitive to the earliest pathological changes of AD.
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http://dx.doi.org/10.3233/JAD-210356DOI Listing
January 2021

MIND Diet, Common Brain Pathologies, and Cognition in Community-Dwelling Older Adults.

J Alzheimers Dis 2021 ;83(2):683-692

Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, USA.

Background: MIND diet, a hybrid of the Mediterranean diet and the Dietary Approaches to Stop Hypertension diet, is associated with a slower cognitive decline and lower risk of Alzheimer's disease (AD) dementia in older adults.

Objective: We aim to examine whether the association of the MIND diet with cognition is independent of common brain pathologies.

Methods: Utilizing data from the Rush Memory and Aging Project (MAP), a longitudinal clinical-pathologic study, we studied 569 decedents with valid dietary data, cognitive testing proximate to death, and complete autopsy data at the time of these analyses. A series of regression analyses were used to examine associations of the MIND diet, dementia-related brain pathologies, and global cognition proximate to death adjusting for age, sex, education, APOEɛ4, late-life cognitive activities, and total energy intake.

Results: A higher MIND diet score was associated with better global cognitive functioning proximate to death (β= 0.119, SE = 0.040, p = 0.003), and neither the strength nor the significance of association changed substantially when AD pathology and other brain pathologies were included in the model. The β-estimate after controlling for global AD pathology was 0.111 (SE = 0.037, p = 0.003). The MIND diet-cognition relationship remained significant when we restricted our analysis to individuals without mild cognitive impairment at the baseline (β= 0.121, SE = 0.042, p = 0.005) or in people diagnosed with postmortem diagnosis of AD based on NIA-Reagan consensus recommendations (β= 0.114, SE = 0.050, p = 0.023).

Conclusion: MIND diet is associated with better cognitive functioning independently of common brain pathology, suggesting that the MIND diet may contribute to cognitive resilience in the elderly.
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http://dx.doi.org/10.3233/JAD-210107DOI Listing
January 2021

ARTS: A novel In-vivo classifier of arteriolosclerosis for the older adult brain.

Neuroimage Clin 2021 24;31:102768. Epub 2021 Jul 24.

Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL, USA; Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, USA; Dept. of Diagnostic Radiology & Nuc Med, Rush University Medical Center, Chicago, IL, USA. Electronic address:

Brain arteriolosclerosis, one of the main pathologies of cerebral small vessel disease, is common in older adults and has been linked to lower cognitive and motor function and higher odds of dementia. In spite of its frequency and associated morbidity, arteriolosclerosis can only be diagnosed at autopsy. Therefore, the purpose of this work was to develop an in-vivo classifier of arteriolosclerosis based on brain MRI. First, an ex-vivo classifier of arteriolosclerosis was developed based on features related to white matter hyperintensities, diffusion anisotropy and demographics by applying machine learning to ex-vivo MRI and pathology data from 119 participants of the Rush Memory and Aging Project (MAP) and Religious Orders Study (ROS), two longitudinal cohort studies of aging that recruit non-demented older adults. The ex-vivo classifier showed good performance in predicting the presence of arteriolosclerosis, with an average area under the receiver operating characteristic curve AUC = 0.78. The ex-vivo classifier was then translated to in-vivo based on available in-vivo and ex-vivo MRI data on the same participants. The in-vivo classifier was named ARTS (short for ARTerioloSclerosis), is fully automated, and provides a score linked to the likelihood a person suffers from arteriolosclerosis. The performance of ARTS in predicting the presence of arteriolosclerosis in-vivo was tested in a separate, 91% dementia-free group of 79 MAP/ROS participants and exhibited an AUC = 0.79 in persons with antemortem intervals shorter than 2.4 years. This level of performance in mostly non-demented older adults is notable considering that arteriolosclerosis can only be diagnosed at autopsy. The scan-rescan reproducibility of the ARTS score was excellent, with an intraclass correlation of 0.99, suggesting that application of ARTS in longitudinal studies may show high sensitivity in detecting small changes. Finally, higher ARTS scores in non-demented older adults were associated with greater decline in cognition two years after baseline MRI, especially in perceptual speed which has been linked to arteriolosclerosis and small vessel disease. This finding was shown in a separate group of 369 non-demented MAP/ROS participants and was validated in 72 non-demented Black participants of the Minority Aging Research Study (MARS) and also in 244 non-demented participants of the Alzheimer's Disease Neuroimaging Initiative 2 and 3. The results of this work suggest that ARTS may have broad implications in the advancement of diagnosis, prevention and treatment of arteriolosclerosis. ARTS is publicly available at https://www.nitrc.org/projects/arts/.
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http://dx.doi.org/10.1016/j.nicl.2021.102768DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8329541PMC
September 2021

Off-label use of aducanumab for cerebral amyloid angiopathy.

Lancet Neurol 2021 08 5;20(8):596-597. Epub 2021 Jul 5.

Department of Brain Repair and Rehabilitation, Stroke Research Centre, University College London Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK.

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http://dx.doi.org/10.1016/S1474-4422(21)00213-1DOI Listing
August 2021

Physical activity, brain tissue microstructure, and cognition in older adults.

PLoS One 2021 7;16(7):e0253484. Epub 2021 Jul 7.

Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, United States of America.

Objective: To test whether postmortem MRI captures brain tissue characteristics that mediate the association between physical activity and cognition in older adults.

Methods: Participants (N = 318) were older adults from the Rush Memory and Aging Project who wore a device to quantify physical activity and also underwent detailed cognitive and motor testing. Following death, cerebral hemispheres underwent MRI to quantify the transverse relaxation rate R2, a metric related to tissue microstructure. For analyses, we reduced the dimensionality of the R2 maps from approximately 500,000 voxels to 30 components using spatial independent component analysis (ICA). Via path analysis, we examined whether these R2 components attenuated the association between physical activity and cognition, controlling for motor abilities and indices of common brain pathologies.

Results: Two of the 30 R2 components were associated with both total daily physical activity and global cognition assessed proximate to death. We visualized these components by highlighting the clusters of voxels whose R2 values contributed most strongly to each. One of these spatial signatures spanned periventricular white matter and hippocampus, while the other encompassed white matter of the occipital lobe. These two R2 components partially mediated the association between physical activity and cognition, accounting for 12.7% of the relationship (p = .01). This mediation remained evident after controlling for motor abilities and neurodegenerative and vascular brain pathologies.

Conclusion: The association between physically activity and cognition in older adults is partially accounted for by MRI-based signatures of brain tissue microstructure. Further studies are needed to elucidate the molecular mechanisms underlying this pathway.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0253484PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8262790PMC
July 2021

The association of epigenetic clocks in brain tissue with brain pathologies and common aging phenotypes.

Neurobiol Dis 2021 Sep 19;157:105428. Epub 2021 Jun 19.

Rush Alzheimer's Disease Center, Chicago, IL, United States of America; Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, United States of America.

Epigenetic clocks are calculated by combining DNA methylation states across select CpG sites to estimate biologic age, and have been noted as the most successful markers of biologic aging to date. Yet, limited research has considered epigenetic clocks calculated in brain tissue. We used DNA methylation states in dorsolateral prefrontal cortex specimens from 721 older participants of the Religious Orders Study and Rush Memory and Aging Project, to calculate DNA methylation age using four established epigenetic clocks: Hannum, Horvath, PhenoAge, GrimAge, and a new Cortical clock. The four established clocks were trained in blood samples (Hannum, PhenoAge, GrimAge) or using 51 human tissue and cell types (Horvath); the recent Cortical clock is the first trained in postmortem cortical tissue. Participants were recruited beginning in 1994 (Religious Orders Study) and 1997 (Memory and Aging Project), and followed annually with questionnaires and clinical evaluations; brain specimens were obtained for 80-90% of participants. Mean age at death was 88.0 (SD 6.7) years. We used linear regression, logistic regression, and linear mixed models, to examine relations of epigenetic clock ages to neuropathologic and clinical aging phenotypes, controlling for chronologic age, sex, education, and depressive symptomatology. Hannum, Horvath, PhenoAge and Cortical clock ages were related to pathologic diagnosis of Alzheimer's disease (AD), as well as to Aβ load (a hallmark pathology of Alzheimer's disease). However, associations were substantially stronger for the Cortical than other clocks; for example, each standard deviation (SD) increase in Hannum, Horvath, and PhenoAge clock age was related to approximately 30% greater likelihood of pathologic AD (all p < 0.05), while each SD increase in Cortical age was related to 90% greater likelihood of pathologic AD (odds ratio = 1.91, 95% confidence interval 1.38, 2.62). Moreover, Cortical age was significantly related to other AD pathology (eg, mean tau tangle density, p = 0.003), and to odds of neocortical Lewy body pathology (for each SD increase in Cortical age, odds ratio = 2.00, 95% confidence 1.27, 3.17), although no clocks were related to cerebrovascular neuropathology. Cortical age was the only epigenetic clock significantly associated with the clinical phenotypes examined, from dementia to cognitive decline (5 specific cognitive systems, and a global cognitive measure averaging 17 tasks) to Parkinsonian signs. Overall, our findings provide evidence of the critical necessity for bespoke clocks of brain aging for advancing research to understand, and eventually prevent, neurodegenerative diseases of aging.
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http://dx.doi.org/10.1016/j.nbd.2021.105428DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8373772PMC
September 2021

Association of Lewy Bodies With Age-Related Clinical Characteristics in Black and White Decedents.

Neurology 2021 08 4;97(8):e825-e835. Epub 2021 Jun 4.

From the Departments of Pathology (Neuropathology) (S.N., J.A.S.), Neurological Sciences (L.L.B., L.Y., A.S.B., D.A.B., J.A.S., R.S.W.), and Psychiatry and Behavioral Sciences (L.L.B., R.S.W.), Rush Alzheimer Disease Center and Rush University Medical Center, Chicago, IL.

Objective: The associations of Lewy bodies (LBs) with olfactory dysfunction, parkinsonism, and higher odds of dementia were assessed in Black and White community-dwelling elders and racial differences in these associations were tested.

Methods: Black decedents (n = 81) were matched 2-to-1 by age, sex, years of education, and follow-up time in the study with White decedents (n = 154) from 4 longitudinal studies of dementia and aging. Participants underwent uniform clinical examination and cognitive, motor, and olfactory testing. LBs were detected in 7 brain regions by α-synuclein immunohistochemistry and racial differences in their association with olfaction, parkinsonism, and odds of dementia were determined using regression analyses.

Results: The mean scores of the odor test, global parkinsonism signs, and global cognition were lower in Black than White decedents; the frequency of dementia was similar in both groups. The frequency of LBs was similar in Black and White decedents (∼25%), as was the frequency of LBs in individual brain regions, while the mean LB counts/mm were similar in all regions except the cingulate cortex, which showed higher mean LB counts in Black decedents. In regression analyses, LBs were associated with impaired olfaction (-2.23, 95% confidence interval [CI] -3.45 to -1.01) and higher odds of dementia (odds ratio 3.0, 95% CI 1.10-8.17) in both racial groups; an association with parkinsonism was stronger in Black than White decedents.

Conclusions: The frequency, distribution, and clinical manifestations of LBs are similar in Black and White elders.
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http://dx.doi.org/10.1212/WNL.0000000000012324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8397586PMC
August 2021

A Genetic Study of Cerebral Atherosclerosis Reveals Novel Associations with and CNOT3.

Genes (Basel) 2021 05 26;12(6). Epub 2021 May 26.

Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA.

Cerebral atherosclerosis is a leading cause of stroke and an important contributor to dementia. Yet little is known about its genetic basis. To examine the association of common single nucleotide polymorphisms with cerebral atherosclerosis severity, we conducted a genomewide association study (GWAS) using data collected as part of two community-based cohort studies in the United States, the Religious Orders Study (ROS) and Rush Memory and Aging Project (MAP). Both studies enroll older individuals and exclude participants with signs of dementia at baseline. From our analysis of 1325 participants of European ancestry who had genotype and neuropathologically assessed cerebral atherosclerosis measures available, we found a novel locus for cerebral atherosclerosis in . The locus comprises eight SNPs, including two independent significant SNPs: rs6664221 ( = -0.27, 95% CI = (-0.35, -0.19), = 1.29 × 10) and rs10881463 ( = -0.20, 95% CI = (-0.27, -0.13), = 3.40 × 10). We further found that the SNPs may influence cerebral atherosclerosis by regulating brain protein expression of CNOT3. CNOT3 is a subunit of CCR4-NOT, which has been shown to be a master regulator of mRNA stability and translation and an important complex for cholesterol homeostasis. In summary, we identify a novel genetic locus for cerebral atherosclerosis and a potential mechanism linking this variation to cerebral atherosclerosis progression. These findings offer insights into the genetic effects on cerebral atherosclerosis.
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http://dx.doi.org/10.3390/genes12060815DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8228534PMC
May 2021

The "cognitive clock": A novel indicator of brain health.

Alzheimers Dement 2021 Jun 1. Epub 2021 Jun 1.

Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, Illinois, USA.

Introduction: We identified a "cognitive clock," a novel indicator of brain health that provides person-specific estimates of cognitive age, and tested the hypothesis that cognitive age is a better predictor of brain health than chronological age in two independent datasets.

Methods: The initial analyses were based on 1057 participants from the Rush Memory and Aging Project and the Religious Orders Study who began without impairment and underwent cognitive assessments up to 24 years. A shape invariant model characterized the latent pattern of cognitive decline, conceptualized here as the "cognitive clock," and yielded person-specific estimates of cognitive age. Survival analyses examined cognitive versus chronological age for predicting Alzheimer's disease dementia, mild cognitive impairment and mortality, and regression analyses examined associations of cognitive versus chronological age with neuropathology and brain atrophy. Finally, we applied the cognitive clock to an independent validation sample of 2592 participants from the Chicago Health and Aging Project, a biracial population-based study, to confirm the predictive utility of cognitive age.

Results: The "cognitive clock" showed that cognition remained stable until a cognitive age of about 80, then declined moderately until 90, then declined precipitously. In the initial dataset, cognitive age was a better predictor of dementia, mild cognitive impairment and mortality than chronological age, and was more strongly associated with neuropathology and brain atrophy. Application of the cognitive clock to the independent validation sample provided further support for the utility of cognitive age as a strong prognostic indicator of adverse outcomes.

Discussion: Cognitive age is a robust prognostic indicator of adverse health outcomes and may serve as a useful biomarker in aging research.
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http://dx.doi.org/10.1002/alz.12351DOI Listing
June 2021

B and T Lymphocyte Densities Remain Stable With Age in Human Cortex.

ASN Neuro 2021 Jan-Dec;13:17590914211018117

Department of Neurology and Neurological Sciences, Stanford School of Medicine, California, United States.

One hallmark of human aging is increased brain inflammation represented by glial activation. With age, there is also diminished function of the adaptive immune system, and modest decreases in circulating B- and T-lymphocytes. Lymphocytes traffic through the human brain and reside there in small numbers, but it is unknown how this changes with age. Thus we investigated whether B- and T-lymphocyte numbers change with age in the normal human brain. We examined 16 human subjects in a pilot study and then 40 human subjects from a single brain bank, ranging in age from 44-96 years old, using rigorous criteria for defining neuropathological changes due to age alone. We immunostained post-mortem cortical tissue for B- and T-lymphocytes using antibodies to CD20 and CD3, respectively. We quantified cell density and made a qualitative assessment of cell location in cortical brain sections, and reviewed prior studies. We report that density and location of both B- and T-lymphocytes do not change with age in the normal human cortex. Solitary B-lymphocytes were found equally in intravascular, perivascular, and parenchymal locations, while T-lymphocytes appeared primarily in perivascular clusters. Thus, any change in number or location of lymphocytes in an aging brain may indicate disease rather than normal aging.
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http://dx.doi.org/10.1177/17590914211018117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8168031PMC
May 2021

Synaptic proteins associated with cognitive performance and neuropathology in older humans revealed by multiplexed fractionated proteomics.

Neurobiol Aging 2021 09 24;105:99-114. Epub 2021 Apr 24.

Massachusetts General Hospital Department of Neurology, Charlestown, MA, USA; Harvard Medical School, Boston, MA, USA.

Alzheimer's disease (AD) is defined by the presence of abundant amyloid-β (Aβ) and tau neuropathology. While this neuropathology is necessary for AD diagnosis, it is not sufficient for causing cognitive impairment. Up to one third of community dwelling older adults harbor intermediate to high levels of AD neuropathology at death yet demonstrate no significant cognitive impairment. Conversely, there are individuals who exhibit dementia with no gross explanatory neuropathology. In prior studies, synapse loss correlated with cognitive impairment. To understand how synaptic composition changes in relation to neuropathology and cognition, multiplexed liquid chromatography mass-spectrometry was used to quantify enriched synaptic proteins from the parietal association cortex of 100 subjects with contrasting levels of AD pathology and cognitive performance. 123 unique proteins were significantly associated with diagnostic category. Functional analysis showed enrichment of serotonin release and oxidative phosphorylation categories in normal (cognitively unimpaired, low neuropathology) and "resilient" (unimpaired despite AD pathology) individuals. In contrast, frail individuals, (low pathology, impaired cognition) showed a metabolic shift towards glycolysis and increased presence of proteasome subunits.
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http://dx.doi.org/10.1016/j.neurobiolaging.2021.04.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8338777PMC
September 2021

Cortical proteins may provide motor resilience in older adults.

Sci Rep 2021 May 28;11(1):11311. Epub 2021 May 28.

Rush Alzheimer's Disease Center, Rush University Medical Center, 1750 West Harrison Street, Jelke Building, Suite 100, Chicago, IL, 60612, USA.

Motor resilience proteins may be a high value therapeutic target that offset the negative effects of pathologies on motor function. This study sought to identify cortical proteins associated with motor decline unexplained by brain pathologies that provide motor resilience. We studied 1226 older decedents with annual motor testing, postmortem brain pathologies and quantified 226 proteotypic peptides in prefrontal cortex. Twenty peptides remained associated with motor decline in models controlling for ten brain pathologies (FDR < 0.05). Higher levels of nine peptides and lower levels of eleven peptides were related to slower decline. A higher motor resilience protein score based on averaging the levels of all 20 peptides was related to slower motor decline, less severe parkinsonism and lower odds of mobility disability before death. Cortical proteins may provide motor resilience. Targeting these proteins in further drug discovery may yield novel interventions to maintain motor function in old age.
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http://dx.doi.org/10.1038/s41598-021-90859-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8163829PMC
May 2021

Tripartite Relationship Among Synaptic, Amyloid, and Tau Proteins: An In Vivo and Postmortem Study.

Neurology 2021 May 4. Epub 2021 May 4.

Memory and Aging Center, Department of Neurology, Weill Institute for Neurosciences, University of California, San Francisco, CA.

Objective: To test the hypothesis that fundamental relationships along the amyloid, tau, and neurodegeneration (A/T/N) cascade depend on synaptic integrity in older adults and postmortem.

Methods: Two independent observational, cross-sectional cohorts: 1) community-dwelling, clinically normal adults from the UCSF Memory and Aging Center completed lumbar puncture and MRI (exclusion criteria, CDR>0), and 2) postmortem decedents from the Rush Memory and Aging Project (exclusion criteria, inability to sign informed consent). measures included cerebrospinal fluid (CSF) synaptic proteins (synaptotagmin-1, SNAP-25, neurogranin, and GAP-43), Aβ, ptau and MRI gray matter volume (GMV). Postmortem measures captured brain tissue levels of presynaptic proteins (complexin-I, complexin-II, VAMP, and SNARE complex), and neuritic plaque and neurofibrillary tangle (NFT) counts. Regression models tested statistical moderation of synaptic protein levels along the A/T/N cascade (synaptic proteins*amyloid on tau, and synaptic proteins*tau on GMV).

Results: 68 in-vivo older adults (age=71y, 43%F) and 633 decedents (age=90y, 68%F, 34% clinically normal) were included. Each CSF synaptic protein moderated the relationship between Aβ and ptau (-0.23<𝛽s<-0.12, ps<0.05) and the relationship between ptau and GMV (-0.49<𝛽s<-0.32, ps<0.05). Individuals with more abnormal CSF synaptic protein demonstrated expected relationships between Aβ-ptau and ptau-brain volume, effects that were absent or reversed in those with more normal CSF synaptic protein. Postmortem analyses recapitulated CSF models. More normal brain tissue levels of complexin-I, VAMP, and SNARE moderated the adverse relationship between neuritic plaque and NFT counts (-0.10<𝛽s<-0.08, ps<0.05).

Conclusions: Pathogenic relationships of Aβ and tau may depend on synaptic state. Synaptic markers may help identify risk and/or resilience to AD proteinopathy.
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http://dx.doi.org/10.1212/WNL.0000000000012145DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8302153PMC
May 2021

The FDA Oncology Center of Excellence Scientific Collaborative: Charting a Course for Applied Regulatory Science Research in Oncology.

Clin Cancer Res 2021 Apr 28. Epub 2021 Apr 28.

Oncology Center of Excellence, U.S. Food and Drug Administration, Silver Spring, Maryland.

The FDA Oncology Center of Excellence (OCE) is a leader within the agency in scientific outreach activities and regulatory science research. On the basis of analysis of scientific workshops, internal meetings, and publications, the OCE identified nine scientific priority areas and one cross-cutting area of high interest for collaboration with external researchers. This article describes the process for identifying these scientific interest areas and highlights funded and unfunded opportunities for external researchers to work with FDA staff on critical regulatory science challenges.
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http://dx.doi.org/10.1158/1078-0432.CCR-20-4429DOI Listing
April 2021

Disrupted Rest-Activity Rhythms and Cerebral Small Vessel Disease Pathology in Older Adults.

Stroke 2021 Jul 27;52(7):2427-2431. Epub 2021 Apr 27.

Division of Neurology, Department of Medicine, Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada (R.S., A.S.P.L.).

Background And Purpose: The pathogenesis of cerebral small vessel disease remains incompletely understood. The relationship between circadian rhythm disturbances and histopathologic measures of cerebral small vessel disease has not been studied. We hypothesized that disrupted circadian rest-activity rhythms would be associated with a higher burden of cerebral small vessel disease pathology.

Methods: We studied 561 community-dwelling older adults (mean age at death, 91.2, 27.4% male) from the Rush Memory and Aging Project. We used actigraphy to quantify several measures of 24-hour rest-activity rhythmicity, including interdaily stability, intradaily variability, and amplitude, and used ordinal logistic regression models to relate these measures to the severity of cerebral arteriolosclerosis, atherosclerosis, macroinfarcts, and microinfarcts, assessed at autopsy.

Results: Lower interdaily stability was associated with a higher burden of arteriolosclerosis, higher intradaily variability was associated with a higher burden of atherosclerosis and subcortical infarcts, and lower amplitude was associated with a higher burden of arteriosclerosis, atherosclerosis and subcortical macroinfarcts. Moreover, the associations between interdaily stability and arteriolosclerosis and intradaily variability and subcortical infarcts were independent of cardiovascular risk factors, sleep fragmentation, and medical comorbidities.

Conclusions: Disrupted rest-activity rhythms are associated with a greater burden of cerebral small vessel disease in older adults.
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http://dx.doi.org/10.1161/STROKEAHA.120.030870DOI Listing
July 2021

Brain insulin signaling and cerebrovascular disease in human postmortem brain.

Acta Neuropathol Commun 2021 04 15;9(1):71. Epub 2021 Apr 15.

Department of Neurology and the Massachusetts Alzheimer's Disease Research Center, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Charlestown, MA, 02129, USA.

Insulin is an important hormone for brain function, and alterations in insulin metabolism may be associated with neuropathology. We examined associations of molecular markers of brain insulin signaling with cerebrovascular disease. Participants were enrolled in the Religious Orders Study (ROS), an ongoing epidemiologic community-based, clinical-pathologic study of aging from across the United States. Using cross-sectional analyses, we studied a subset of ROS: 150 persons with or without diabetes, matched 1:1 by sex on age-at-death and education. We used ELISA, immunohistochemistry, and ex vivo stimulation with insulin, to document insulin signaling in postmortem midfrontal gyrus cortex tissue. Postmortem neuropathologic data identified cerebrovascular disease including brain infarcts, classified by number (as none for the reference; one; and more than one), size (gross and microscopic infarcts), and brain region/location (cortical and subcortical). Cerebral vessel pathologies were assessed, including severity of atherosclerosis, arteriolosclerosis, and amyloid angiopathy. In separate regression analyses, greater AKT1 phosphorylation at T following ex vivo stimulation with insulin (OR = 1.916; estimate = 0.650; p = 0.007) and greater pSIRS1 immunolabeling in neuronal cytoplasm (OR = 1.610; estimate = 0.476; p = 0.013), were each associated with a higher number of brain infarcts. Secondary analyses showed consistent results for gross infarcts and microinfarcts separately, but no other association including by infarct location (cortical or subcortical). AKT S phosphorylation following insulin stimulation was associated with less amyloid angiopathy severity, but not with other vessel pathology including atherosclerosis and arteriolosclerosis. In summary, insulin resistance in the human brain, even among persons without diabetes, is associated with cerebrovascular disease and especially infarcts. The underlying pathophysiologic mechanisms need further elucidation. Because brain infarcts are known to be associated with lower cognitive function and dementia, these data are relevant to better understanding the link between brain metabolism and brain function.
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http://dx.doi.org/10.1186/s40478-021-01176-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8048276PMC
April 2021

Association of Hemoglobin A1C With TDP-43 Pathology in Community-Based Elders.

Neurology 2021 Apr 14. Epub 2021 Apr 14.

Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, USA.

Objective: We tested the hypothesis that an inverse association exists between diabetes mellitus (DM) and hemoglobin A1C (A1C) with Transactive response DNA binding protein 43 (TDP-43) levels in older adults.

Methods: We leveraged antemortem and postmortem data of decedents from three community-based clinical-pathological studies. DM status, A1C levels, and medications for DM were documented annually. TDP-43 cytoplasmic inclusions, evaluated in 6 brain regions using immunohistochemistry, were used to obtain a semiquantitative TDP-43 score (0-5) in each region, and scores were averaged across regions to obtain a TDP-43 severity score. We used linear regressions to test the association of DM and A1C with the TDP-43 severity score.

Results: On average, participants (n=817) were 90 years old at the time of death, three fourth were women, and one fourth had DM. The mean A1C was 6.0% (SD=0.6). TDP-43 was observed in 54% of participants, and the mean TDP-43 score was 0.7 (range 0-4.5). A higher level of A1C was associated with a lower TDP-43 score (estimate=-0.156, S.E.=0.060, =0.009) while DM had a borderline inverse association with the TDP-43 score (estimate=-0.163, S.E.=0.087, =0.060). The association of higher levels of A1C with lower TDP-43 scores persisted after further adjustment by 4, vascular risk factors, stroke, and hypoglycemic medications. Exclusion of the oldest old participants did not change the results.

Conclusion: Overall, the results suggest that a high level of A1C is associated with less TDP-43 proteinopathy in older persons while the relationship of DM with TDP-43 needs further study.
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http://dx.doi.org/10.1212/WNL.0000000000012025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8205465PMC
April 2021

Late-Life Vascular Risk Score in Association With Postmortem Cerebrovascular Disease Brain Pathologies.

Stroke 2021 Jun 12;52(6):2060-2067. Epub 2021 Apr 12.

Rush Alzheimer's Disease Center (S.O., L.Y., A.C., Z.A., L.L.B., J.A.S., D.A.B., A.S.B.), Rush University Medical Center, Chicago, IL.

Background And Purpose: The general cardiovascular Framingham risk score (FRS) identifies adults at increased risk for stroke. We tested the hypothesis that baseline FRS is associated with the presence of postmortem cerebrovascular disease (CVD) pathologies.

Methods: We studied the brains of 1672 older decedents with baseline FRS and measured CVD pathologies including macroinfarcts, microinfarcts, atherosclerosis, arteriolosclerosis, and cerebral amyloid angiopathy. We employed a series of logistic regressions to examine the association of baseline FRS with each of the 5 CVD pathologies.

Results: Average age at baseline was 80.5±7.0 years and average age at death was 89.2±6.7 years. A higher baseline FRS was associated with higher odds of macroinfarcts (odds ratio, 1.10 [95% CI, 1.07-1.13], <0.001), microinfarcts (odds ratio, 1.04 [95% CI, 1.01-1.07], =0.009), atherosclerosis (odds ratio, 1.07 [95% CI, 1.04-1.11], <0.001), and arteriolosclerosis (odds ratio, 1.04 [95% CI, 1.01-1.07], =0.005). C statistics for these models ranged from 0.537 to 0.595 indicating low accuracy for predicting CVD pathologies. FRS was not associated with the presence of cerebral amyloid angiopathy.

Conclusions: A higher FRS score in older adults is associated with higher odds of some, but not all, CVD pathologies, with low discrimination at the individual level. Further work is needed to develop a more robust risk score to identify adults at risk for accumulating CVD pathologies.
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http://dx.doi.org/10.1161/STROKEAHA.120.030226DOI Listing
June 2021

PLD3 is a neuronal lysosomal phospholipase D associated with β-amyloid plaques and cognitive function in Alzheimer's disease.

PLoS Genet 2021 04 8;17(4):e1009406. Epub 2021 Apr 8.

Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America.

Phospholipase D3 (PLD3) is a protein of unclear function that structurally resembles other members of the phospholipase D superfamily. A coding variant in this gene confers increased risk for the development of Alzheimer's disease (AD), although the magnitude of this effect has been controversial. Because of the potential significance of this obscure protein, we undertook a study to observe its distribution in normal human brain and AD-affected brain, determine whether PLD3 is relevant to memory and cognition in sporadic AD, and to evaluate its molecular function. In human neuropathological samples, PLD3 was primarily found within neurons and colocalized with lysosome markers (LAMP2, progranulin, and cathepsins D and B). This colocalization was also present in AD brain with prominent enrichment on lysosomal accumulations within dystrophic neurites surrounding β-amyloid plaques. This pattern of protein distribution was conserved in mouse brain in wild type and the 5xFAD mouse model of cerebral β-amyloidosis. We discovered PLD3 has phospholipase D activity in lysosomes. A coding variant in PLD3 reported to confer AD risk significantly reduced enzymatic activity compared to wild-type PLD3. PLD3 mRNA levels in the human pre-frontal cortex inversely correlated with β-amyloid pathology severity and rate of cognitive decline in 531 participants enrolled in the Religious Orders Study and Rush Memory and Aging Project. PLD3 levels across genetically diverse BXD mouse strains and strains crossed with 5xFAD mice correlated strongly with learning and memory performance in a fear conditioning task. In summary, this study identified a new functional mammalian phospholipase D isoform which is lysosomal and closely associated with both β-amyloid pathology and cognition.
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http://dx.doi.org/10.1371/journal.pgen.1009406DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8031396PMC
April 2021

To what degree is late life cognitive decline driven by age-related neuropathologies?

Brain 2021 08;144(7):2166-2175

Rush University Medical Center, Rush Alzheimer's Disease Center, Chicago, IL 60612, USA.

The ageing brain is vulnerable to a wide array of neuropathologies. Prior work estimated that the three most studied of these, Alzheimer's disease, infarcts, and Lewy bodies, account for ∼40% of the variation in late life cognitive decline. However, that estimate did not incorporate many other diseases that are now recognized as potent drivers of cognitive decline [e.g. limbic predominant age-related TDP-43 encephalopathy (LATE-NC), hippocampal sclerosis, other cerebrovascular conditions]. We examined the degree to which person-specific cognitive decline in old age is driven by a wide array of neuropathologies. Deceased participants (n = 1164) from two longitudinal clinical-pathological studies, the Rush Memory and Aging Project and Religious Orders Study, completed up to 24 annual evaluations including 17 cognitive performance tests and underwent brain autopsy. Neuropathological examinations provided 11 pathological indices, including markers of Alzheimer's disease, non- Alzheimer's disease neurodegenerative diseases (i.e. LATE-NC, hippocampal sclerosis, Lewy bodies), and cerebrovascular conditions (i.e. macroscopic infarcts, microinfarcts, cerebral amyloid angiopathy, atherosclerosis, and arteriolosclerosis). Mixed effects models examined the linear relation of pathological indices with global cognitive decline, and random change point models examined the relation of the pathological indices with the onset of terminal decline and rates of preterminal and terminal decline. Cognition declined an average of about 0.10 unit per year (estimate = -0.101, SE = 0.003, P < 0.001) with considerable heterogeneity in rates of decline (variance estimate for the person-specific slope of decline was 0.0094, P < 0.001). When considered separately, 10 of 11 pathological indices were associated with faster decline and accounted for between 2% and 34% of the variation in decline, respectively. When considered simultaneously, the 11 pathological indices together accounted for 43% of the variation in decline; Alzheimer's disease-related indices accounted for 30-36% of the variation, non-Alzheimer's disease neurodegenerative indices 4-10%, and cerebrovascular indices 3-8%. Finally, the 11 pathological indices combined accounted for less than a third of the variation in the onset of terminal decline (28%) and rates of preterminal (32%) and terminal decline (19%). Although age-related neuropathologies account for a large proportion of the variation in late life cognitive decline, considerable variation remains unexplained even after considering a wide array of neuropathologies. These findings highlight the complexity of cognitive ageing and have important implications for the ongoing effort to develop effective therapeutics and identify novel treatment targets.
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http://dx.doi.org/10.1093/brain/awab092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8370442PMC
August 2021

Proteomic identification of select protein variants of the SNARE interactome associated with cognitive reserve in a large community sample.

Acta Neuropathol 2021 05 1;141(5):755-770. Epub 2021 Mar 1.

Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada.

Age-related neuropathologies progressively impair cognitive abilities by damaging synaptic function. We aimed to identify key components within the presynaptic SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) machinery associated with cognitive performance and estimate their potential contribution to brain reserve in old age. We used targeted SRM proteomics to quantify amounts of 60 peptides, encoded in 30 different genes, in postmortem specimens of the prefrontal cortex from 1209 participants of two aging studies, with available antemortem cognitive evaluations and postmortem neuropathologic assessments. We found that select (but not all) proteoforms are strongly associated with cognitive function and the burden of Alzheimer's disease (AD) pathology. Specifically, greater abundance of STX1A (but not other syntaxins), SYT12, full-length SNAP25, and the GABAergic STXBP1 variant were robustly associated with better cognitive performance. By contrast, greater abundance of other presynaptic proteins (e.g., STXBP5 or tomosyn, STX7, or SYN2) showed a negative influence on cognition. Regression models adjusting for demographic and pathologic variables showed that altered levels of these protein species explained 7.7% additional between-subject variance in cognition (more than any individual age-related neuropathology in the model), suggesting that these molecules constitute key elements of brain reserve. Network analyses indicated that those peptides associated with brain reserve, and closest to the SNARE fusogenic activity, showed greater centrality measures and were better connected in the network. Validation assays confirmed the selective loss of the STX1A (but not STX1B) isoform in cognitively impaired cases. In rodent and human brains, STX1A was selectively located at glutamatergic terminals. However, in AD brains, STX1A was redistributed adjacent to neuritic pathology, and markedly expressed in astrocytes. Our study provides strong evidence, indicating that select presynaptic proteins are key in maintaining brain reserve. Compromised ability to sustain expression levels of these proteins may trigger synaptic dysfunction and concomitant cognitive impairment.
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http://dx.doi.org/10.1007/s00401-021-02282-7DOI Listing
May 2021

Limbic-predominant age-related TDP-43 encephalopathy neuropathologic change and microvascular pathologies in community-dwelling older persons.

Brain Pathol 2021 May 23;31(3):e12939. Epub 2021 Feb 23.

Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, USA.

Limbic-predominant age-related transactive response DNA-binding protein 43 (TDP-43) encephalopathy neuropathologic change (LATE-NC) and microvascular pathologies, including microinfarcts, cerebral amyloid angiopathy (CAA), and arteriolosclerosis are common in old age. A relationship between LATE-NC and arteriolosclerosis has been reported in some but not all studies. The objectives of this study were to investigate the frequency of co-occurring LATE-NC and microvascular pathologies and test the hypothesis that arteriolosclerosis, specifically, is related to LATE-NC in brains from community-dwelling older persons. Analyses included 749 deceased participants with completed data on LATE-NC and microvascular pathology from 3 longitudinal clinical pathologic studies of aging. Given the specific interest in arteriolosclerosis, we expanded the examination of arteriolosclerosis to include not only the basal ganglia but also two additional white matter regions from anterior and posterior watershed territories. Ordinal logistic regression models examined the association of microvascular pathology with LATE-NC. LATE-NC was present in 409 (54.6%) decedents, of which 354 (86.5%) had one or multiple microvascular pathologies including 132 (32.3%) with moderate-severe arteriolosclerosis in basal ganglia, 195 (47.6%) in anterior watershed, and 144 (35.2%) in posterior watershed; 170 (41.5%) with moderate-severe CAA, and 150 (36.6%) with microinfarcts. In logistic regression models, only posterior watershed arteriolosclerosis, but not other regions of arteriolosclerosis was associated with a higher odds of more advanced LATE-NC stages (Odds Ratio = 1.12; 95% Confidence Interval = 1.01-1.25) after controlling for demographics, AD, and other age-related pathologies. Capillary CAA, but not the severity of CAA was associated with an increased odds of LATE-NC burden (Odds Ratio = 1.71; 95% Confidence Interval = 1.13-2.58). Findings were unchanged in analyses controlling for APOE ε4, vascular risk factors, or vascular diseases. These findings suggest that LATE-NC with microvascular pathology is a very common mixed pathology and small vessel disease pathology may contribute to LATE-NC in the aging brain.
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http://dx.doi.org/10.1111/bpa.12939DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8363209PMC
May 2021

What is 'Alzheimer's disease'? The neuropathological heterogeneity of clinically defined Alzheimer's dementia.

Curr Opin Neurol 2021 04;34(2):237-245

Rush Alzheimer's Disease Center, Chicago, Illinois, USA.

Purpose Of Review: Beta-amyloid with paired helical filaments (PHF)-tau neurofibrillary tangles define hallmark Alzheimer's disease neuropathologic changes (AD-NC). Yet persons with Alzheimer's dementia, defined broadly as an amnestic multidomain progressive dementia, often exhibit postmortem evidence of other neuropathologies including other neurodegenerative (Lewy body disease and transactive response DNA-binding protein disease) and vascular-related brain lesions. Clinicopathologic and epidemiologic analyses demonstrate the significance of these substrates, as coinciding neuropathologies mitigate the threshold for diagnosis of Alzheimer's dementia. In addition, other biologic processes may also independently underlie a progressive amnestic dementia. Advances in research on the relationship between age-related cognitive decline and the underlying neuropathologic substrates indicate that consensus neuropathologic criteria or disease nomenclature may need new considerations or refinement. This review appraises seminal literature as well as mixed pathologies and biological factors that may be determinants of clinical and pathologic disease.

Recent Findings: Cognition in aging (spanning from normal cognition to dementia) represents a clinical continuum. Traditional neuropathologic substrates of dementia however do not explain the variability of cognitive decline. Conversely, not all patients with AD-NC exhibit symptomatology of Alzheimer's dementia. In addition to diagnostic plaques and tangles, other neurodegenerative, cerebrovascular, and perivascular substrates manifest through discrete tissue lesions. Factors related to energetics, neurogenetics, neuroimmunology, resilience, proteinopathies, and waste clearance are increasingly suggested to be general drivers of disease. Recognition of novel neuroimmune pathways and brain-body connections further suggest there may be broader extracranial determinants of person-specific disease.

Summary: Alzheimer's dementia is a pathologically heterogeneous and biologically multilayered disease. Recent studies and exercises in nomenclature reveal shortcomings in existing terminologies. Recognizing and overcoming these limitations is required for experts to effectively communicate about and ultimately prevent and treat Alzheimer's dementia.
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http://dx.doi.org/10.1097/WCO.0000000000000912DOI Listing
April 2021

Regional brain iron associated with deterioration in Alzheimer's disease: A large cohort study and theoretical significance.

Alzheimers Dement 2021 07 25;17(7):1244-1256. Epub 2021 Jan 25.

Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, and The University of Melbourne, Parkville, Australia.

Objective: This paper is a proposal for an update of the iron hypothesis of Alzheimer's disease (AD), based on large-scale emerging evidence.

Background: Iron featured historically early in AD research efforts for its involvement in the amyloid and tau proteinopathies, APP processing, genetics, and one clinical trial, yet iron neurochemistry remains peripheral in mainstream AD research. Much of the effort investigating iron in AD has focused on the potential for iron to provoke the onset of disease, by promoting proteinopathy though increased protein expression, phosphorylation, and aggregation.

New/updated Hypothesis: We provide new evidence from a large post mortem cohort that brain iron levels within the normal range were associated with accelerated ante mortem disease progression in cases with underlying proteinopathic neuropathology. These results corroborate recent findings that argue for an additional downstream role for iron as an effector of neurodegeneration, acting independently of tau or amyloid pathologies. We hypothesize that the level of tissue iron is a trait that dictates the probability of neurodegeneration in AD by ferroptosis, a regulated cell death pathway that is initiated by signals such as glutathione depletion and lipid peroxidation.

Major Challenges For The Hypothesis: While clinical biomarkers of ferroptosis are still in discovery, the demonstration of additional ferroptotic correlates (genetic or biomarker derived) of disease progression is required to test this hypothesis. The genes implicated in familial AD are not known to influence ferroptosis, although recent reports on APP mutations and apolipoprotein E allele (APOE) have shown impact on cellular iron retention. Familial AD mutations will need to be tested for their impact on ferroptotic vulnerability. Ultimately, this hypothesis will be substantiated, or otherwise, by a clinical trial of an anti-ferroptotic/iron compound in AD patients.

Linkage To Other Major Theories: Iron has historically been linked to the amyloid and tau proteinopathies of AD. Tau, APP, and apoE have been implicated in physiological iron homeostasis in the brain. Iron is biochemically the origin of most chemical radicals generated in biochemistry and thus closely associated with the oxidative stress theory of AD. Iron accumulation is also a well-established consequence of aging and inflammation, which are major theories of disease pathogenesis.
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http://dx.doi.org/10.1002/alz.12282DOI Listing
July 2021

A cortical immune network map identifies distinct microglial transcriptional programs associated with β-amyloid and Tau pathologies.

Transl Psychiatry 2021 01 14;11(1):50. Epub 2021 Jan 14.

Center for Translational & Computational Neuroimmunology, Department of Neurology, Columbia University Medical Center, New York, NY, USA.

Microglial dysfunction has been proposed as one of the many cellular mechanisms that can contribute to the development of Alzheimer's disease (AD). Here, using a transcriptional network map of the human frontal cortex, we identify five modules of co-expressed genes related to microglia and assess their role in the neuropathologic features of AD in 540 subjects from two cohort studies of brain aging. Two of these transcriptional programs-modules 113 and 114-relate to the accumulation of β-amyloid, while module 5 relates to tau pathology. We replicate these associations in brain epigenomic data and in two independent datasets. In terms of tau, we propose that module 5, a marker of activated microglia, may lead to tau accumulation and subsequent cognitive decline. We validate our model further by showing that three representative module 5 genes (ACADVL, TRABD, and VASP) encode proteins that are upregulated in activated microglia in AD.
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http://dx.doi.org/10.1038/s41398-020-01175-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7809035PMC
January 2021

Early Selective Vulnerability of the CA2 Hippocampal Subfield in Primary Age-Related Tauopathy.

J Neuropathol Exp Neurol 2021 01;80(2):102-111

Institute of Neurology, Medical University of Vienna, Vienna, Austria.

Primary age-related tauopathy (PART) is a neurodegenerative entity defined as Alzheimer-type neurofibrillary degeneration primarily affecting the medial temporal lobe with minimal to absent amyloid-β (Aβ) plaque deposition. The extent to which PART can be differentiated pathoanatomically from Alzheimer disease (AD) is unclear. Here, we examined the regional distribution of tau pathology in a large cohort of postmortem brains (n = 914). We found an early vulnerability of the CA2 subregion of the hippocampus to neurofibrillary degeneration in PART, and semiquantitative assessment of neurofibrillary degeneration in CA2 was significantly greater than in CA1 in PART. In contrast, subjects harboring intermediate-to-high AD neuropathologic change (ADNC) displayed relative sparing of CA2 until later stages of their disease course. In addition, the CA2/CA1 ratio of neurofibrillary degeneration in PART was significantly higher than in subjects with intermediate-to-high ADNC burden. Furthermore, the distribution of tau pathology in PART diverges from the Braak NFT staging system and Braak stage does not correlate with cognitive function in PART as it does in individuals with intermediate-to-high ADNC. These findings highlight the need for a better understanding of the contribution of PART to cognitive impairment and how neurofibrillary degeneration interacts with Aβ pathology in AD and PART.
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http://dx.doi.org/10.1093/jnen/nlaa153DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8453611PMC
January 2021

Single cell RNA sequencing of human microglia uncovers a subset associated with Alzheimer's disease.

Nat Commun 2020 11 30;11(1):6129. Epub 2020 Nov 30.

Center for Translational and Computational Neuroimmunology, Columbia University Medical Center, New York, NY, USA.

The extent of microglial heterogeneity in humans remains a central yet poorly explored question in light of the development of therapies targeting this cell type. Here, we investigate the population structure of live microglia purified from human cerebral cortex samples obtained at autopsy and during neurosurgical procedures. Using single cell RNA sequencing, we find that some subsets are enriched for disease-related genes and RNA signatures. We confirm the presence of four of these microglial subpopulations histologically and illustrate the utility of our data by characterizing further microglial cluster 7, enriched for genes depleted in the cortex of individuals with Alzheimer's disease (AD). Histologically, these cluster 7 microglia are reduced in frequency in AD tissue, and we validate this observation in an independent set of single nucleus data. Thus, our live human microglia identify a range of subtypes, and we prioritize one of these as being altered in AD.
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http://dx.doi.org/10.1038/s41467-020-19737-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7704703PMC
November 2020

Vitamin D and Vitamin K Concentrations in Human Brain Tissue Are Influenced by Freezer Storage Time: The Memory and Aging Project.

J Nutr 2021 01;151(1):104-108

Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA.

Background: Vitamins D and K, which are present in human brain, may have a role in neurodegenerative disease.

Objectives: Given the interest in measuring nutrient concentrations in archived brain samples, it is important to evaluate whether freezer storage time affects these concentrations. Therefore, we evaluated differences in vitamin D and vitamin K concentrations in human brain samples stored for various lengths of time.

Methods: Postmortem brain samples were obtained from 499 participants in the Rush Memory and Aging Project (mean age 92 y, 72% female). Concentrations of vitamins D and K and their metabolites were measured in 4 regions (midtemporal cortex, midfrontal cortex, cerebellum, anterior watershed white matter) using LC-MS/MS and HPLC, respectively. The predominant forms were 25-hydroxycholecalciferol [25(OH)D3] and menaquinone-4 (MK4). ANOVA was used to determine if concentrations differed according to storage time.

Results: The geometric mean of the mean 25(OH)D3 concentration (across 4 regions) in brains stored for 1.1 to 6.0 y did not differ from that in brains stored ≤1.0 y (all P ≥ 0.37), whereas 25(OH)D3 in brains stored >6.0 y was 31-40% lower (P ≤ 0.003). MK4 had similar results, with the geometric mean MK4 concentration in the brains stored ≥9.0 y being 48-52% lower than those in brains stored ≤1.0 y (P ≤ 0.012). The 25(OH)D3 and MK4 concentrations were positively correlated across all 4 regions (all Spearman ρ ≥ 0.79, P < 0.001).

Conclusions: 25(OH)D3 and MK4 appear to be stable in brain tissue from older adults stored at -80°C for up to 6 and 9 y, respectively, but not longer. Freezer storage time should be considered in the design and interpretation of studies using archived brain tissue.
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http://dx.doi.org/10.1093/jn/nxaa336DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7779216PMC
January 2021

Association of Low Systolic Blood Pressure with Postmortem Amyloid-β and Tau.

J Alzheimers Dis 2020 ;78(4):1755-1764

Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, USA.

Background: Vascular mechanisms may contribute to the accumulation of AD pathology.

Objective: We examined whether the burden of vascular risk factors proximate to death is associated with amyloid-β and tau levels or modified their known association.

Methods: We examined the brains of 1, 585 participants from two longitudinal community-based studies of older adults. Amyloid-β and tau were quantified by postmortem examination. The burden of vascular risk factors was summarized by calculating the Framingham general cardiovascular risk score (FRS) proximate to death. Using linear regressions, we examined the association of the FRS with the amyloid-β and tau levels and examined if the FRS modified the association of the amyloid-β with tau.

Results: On average, participants were nearly 90 years old and two-thirds were women. The FRS was not associated with amyloid-β (Spearman r  = -0.00, p  = 0.918) or tau (r = 0.01, p = 0.701). However, the FRS as a whole (estimate = -0.022, SE = 0.008, p = 0.009), and specifically the systolic blood pressure (SBP) component (estimate = -0.033, SE = 0.012, p = 0.009), modified the association of the amyloid-β with tau. Further analysis showed that the association between amyloid-β and tau was stronger at lower levels of SBP.

Conclusion: Late-life vascular risk scores were not related to postmortem levels of amyloid-β or tau. However, lower levels of vascular risk scores and SBP were associated with a stronger association between amyloid-β and tau. These data suggest that vascular risk factors may modify the relation of AD pathology markers to one another.
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http://dx.doi.org/10.3233/JAD-200412DOI Listing
January 2020
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