This prospective study seeks to examine the utility of subjective cognitive decline (SCD) as a marker of future progression to dementia in a community-based cohort of non-Latinx White, non-Latinx ...Black, and Latinx individuals. Debate surrounds the utility of SCD, the subjective perception of decline in one's cognition before such impairment is evident in traditional neuropsychological assessments, as an early indicator of impending Alzheimer disease. Unfortunately, most studies examining SCD have been conducted in non-Latinx White samples and commonly exclude groups of individuals shown to be most vulnerable to dementia.
Participants were enrolled into this cohort study from the Washington Heights-Inwood Columbia Aging Project if they were cognitively unimpaired, had baseline measurement of SCD, and self-identified as non-Latinx White, non-Latinx Black, or Latinx. SCD was measured as a continuous sum of 10 items assessing cognitive complaints. Competing risk models tested the main effects of baseline SCD on progression to dementia. Models were adjusted for age, sex/gender, years of education, medical comorbidity burden, enrollment cohort, and baseline memory test performance with death jointly modelled as a function of race/ethnicity.
A total of 4,043 (1,063 non-Latinx White, 1,267 non-Latinx Black, and 1,713 Latinx) participants were selected for this study with a mean age of 75 years, 67% women, and with a mean follow-up of 5 years. Higher baseline SCD was associated with increased rates of incident dementia over time in the full sample (hazard ratio HR 1.085, CI 1.047-1.125,
< 0.001) and within Latinx (HR 1.084, CI 1.039-1.130,
< 0.001) and non-Latinx Black individuals (HR 1.099, CI 1.012-1.194,
= 0.024).
Overall results of this study support SCD as a prodromal marker of dementia in a multiracial community sample, and in Latinx and non-Latinx Black individuals in particular. Because models examining the risk of dementia were adjusted for baseline memory test performance, the results support the idea that SCD, a subjective reflection of one's own current cognitive functioning, contributes information above and beyond standard memory testing. Current findings highlight the importance of carefully evaluating any memory concerns raised by older adults during routine visits and underscore the potential utility of screening older adults for SCD.
This study aimed to investigate the association between dietary prebiotic intake and risk for Alzheimer's disease (AD).
This longitudinal study includes 1,837 elderly (≥65 years) participants of a ...multi-ethnic community-based cohort study who were dementia-free at baseline and had provided dietary information from food frequency questionnaires. Total daily intake of fructan, one of the best-known prebiotics, was calculated based on consumption frequency and fructan content per serving of 8 food items. The associations of daily fructan intake with AD risk were examined using a Cox proportional hazards model, adjusted for cohort recruitment wave, age, gender, race/ethnicity, education, daily caloric intake, and APOE genotype. Effect modification by race/ethnicity, APOE genotype, and gender was tested by including an interaction term into the Cox models, as well as by stratified analyses.
Among 1,837 participants (1,263 women 69%; mean SD age = 76 6.3 years), there were 391 incident AD cases during a mean follow-up of 7.5 years (13736 person-years). Each additional gram of fructan intake was associated with 24% lower risk for AD ((95% CI)=0.60-0.97; P =0.03). Additional adjusting for smoking, alcohol consumption, and comorbidity index did not change results materially. The associations were not modified by race/ethnicity, gender, and APOE genotype, although stratified analyses showed that fructan intake was significantly associated with reduced AD risk in Hispanics but not in non-Hispanic Blacks or Whites.
Higher dietary fructan intake is associated with a reduced risk of clinical Alzheimer's disease among older adults.
Results from longitudinal studies suggest that regular leisure time physical activity (LTPA) is associated with reduced risk of dementia or Alzheimer disease. Data on the association between LTPA and ...brain magnetic resonance imaging (MRI) measures remain scarce and inconsistent.
To examine the association of LTPA and MRI-assessed brain aging measures in a multiethnic elderly population.
This cross-sectional study included 1443 older (≥65 years) adults without dementia who were participants of the Washington/Hamilton Heights-Inwood Columbia Aging Project study. LTPA, from self-reported questionnaire, was calculated as metabolic equivalent of energy expenditure. Both moderate to vigorous LTPA, assessed as meeting Physical Activity Guidelines for Americans (≥150 minutes/week) or not, and light-intensity LTPA were also examined.
LTPA.
Primary outcomes included total brain volume (TBV), cortical thickness, and white matter hyperintensity volume, all derived from MRI scans with established methods and adjusted for intracranial volume when necessary. We examined the association of LTPA with these imaging markers using regression models adjusted for demographic, clinical, and vascular risk factors.
The 1443 participants of the study had a mean (SD) age of 77.2 (6.4) years; 921 (63.8%) were women; 27.0%, 34.4%, and 36.3% were non-Hispanic White, non-Hispanic African American, and Hispanic individuals, respectively; and 27.3% carried the apolipoprotein E (APOE) ɛ4 allele. Compared with the LTPA of nonactive older adults, those with the most LTPA had larger (in cm3) TBV (β SE, 13.17 4.42 cm3; P = .003; P for trend = .006) and greater cortical thickness (β SE, 0.016 0.008 mm; P = .05; P for trend = .03). The effect size comparing the highest LTPA level with the nonactive group was equivalent to approximately 3 to 4 years of aging (β for 1 year older, -3.06 and -0.005 for TBV and cortical thickness, respectively). A dose-response association was found and even the lowest LTPA level had benefits (eg, TBV: β SE, 9.03 4.26 cm3; P = .03) compared with the nonactive group. Meeting Physical Activity Guidelines for Americans (TBV: β SE, 18.82 5.14 cm3; P < .001) and light-intensity LTPA (TBV: β SE, 9.26 4.29 cm3; P = .03) were also associated with larger brain measures. The association between LTPA and TBV was moderated by race/ethnicity, sex, and APOE status, but generally existed in all subgroups. The results remained similar after excluding participants with mild cognitive impairment.
In this study, more physical activity was associated with larger brain volume in older adults. Longitudinal studies are warranted to explore the potential role of physical activity in brain health among older individuals.
More than 75 common variant loci account for only a portion of the heritability for Alzheimer's disease (AD). A more complete understanding of the genetic basis of AD can be deduced by exploring ...associations with AD-related endophenotypes.
We conducted genome-wide scans for cognitive domain performance using harmonized and co-calibrated scores derived by confirmatory factor analyses for executive function, language, and memory. We analyzed 103,796 longitudinal observations from 23,066 members of community-based (FHS, ACT, and ROSMAP) and clinic-based (ADRCs and ADNI) cohorts using generalized linear mixed models including terms for SNP, age, SNP × age interaction, sex, education, and five ancestry principal components. Significance was determined based on a joint test of the SNP's main effect and interaction with age. Results across datasets were combined using inverse-variance meta-analysis. Genome-wide tests of pleiotropy for each domain pair as the outcome were performed using PLACO software.
Individual domain and pleiotropy analyses revealed genome-wide significant (GWS) associations with five established loci for AD and AD-related disorders (BIN1, CR1, GRN, MS4A6A, and APOE) and eight novel loci. ULK2 was associated with executive function in the community-based cohorts (rs157405, P = 2.19 × 10
). GWS associations for language were identified with CDK14 in the clinic-based cohorts (rs705353, P = 1.73 × 10
) and LINC02712 in the total sample (rs145012974, P = 3.66 × 10
). GRN (rs5848, P = 4.21 × 10
) and PURG (rs117523305, P = 1.73 × 10
) were associated with memory in the total and community-based cohorts, respectively. GWS pleiotropy was observed for language and memory with LOC107984373 (rs73005629, P = 3.12 × 10
) in the clinic-based cohorts, and with NCALD (rs56162098, P = 1.23 × 10
) and PTPRD (rs145989094, P = 8.34 × 10
) in the community-based cohorts. GWS pleiotropy was also found for executive function and memory with OSGIN1 (rs12447050, P = 4.09 × 10
) and PTPRD (rs145989094, P = 3.85 × 10
) in the community-based cohorts. Functional studies have previously linked AD to ULK2, NCALD, and PTPRD.
Our results provide some insight into biological pathways underlying processes leading to domain-specific cognitive impairment and AD, as well as a conduit toward a syndrome-specific precision medicine approach to AD. Increasing the number of participants with harmonized cognitive domain scores will enhance the discovery of additional genetic factors of cognitive decline leading to AD and related dementias.
Prior studies indicate psychiatric symptoms such as depression, apathy and anxiety are risk factors for or prodromal symptoms of incipient Alzheimer's disease. The study of persons at 50% risk for ...inheriting autosomal dominant Alzheimer's disease mutations allows characterization of these symptoms before progressive decline in a population destined to develop illness. We sought to characterize early behavioural features in carriers of autosomal dominant Alzheimer's disease mutations. Two hundred and sixty-one persons unaware of their mutation status enrolled in the Dominantly Inherited Alzheimer Network, a study of persons with or at-risk for autosomal dominant Alzheimer's disease, were evaluated with the Neuropsychiatric Inventory-Questionnaire, the 15-item Geriatric Depression Scale and the Clinical Dementia Rating Scale (CDR). Ninety-seven asymptomatic (CDR = 0), 25 mildly symptomatic (CDR = 0.5), and 33 overtly affected (CDR > 0.5) autosomal dominant Alzheimer's disease mutation carriers were compared to 106 non-carriers with regard to frequency of behavioural symptoms on the Neuropsychiatric Inventory-Questionnaire and severity of depressive symptoms on the Geriatric Depression Scale using generalized linear regression models with appropriate distributions and link functions. Results from the adjusted analyses indicated that depressive symptoms on the Neuropsychiatric Inventory-Questionnaire were less common in cognitively asymptomatic mutation carriers than in non-carriers (5% versus 17%, P = 0.014) and the odds of experiencing at least one behavioural sign in cognitively asymptomatic mutation carriers was lower than in non-carriers (odds ratio = 0.50, 95% confidence interval: 0.26-0.98, P = 0.042). Depression (56% versus 17%, P = 0.0003), apathy (40% versus 4%, P < 0.0001), disinhibition (16% versus 2%, P = 0.009), irritability (48% versus 9%, P = 0.0001), sleep changes (28% versus 7%, P = 0.003), and agitation (24% versus 6%, P = 0.008) were more common and the degree of self-rated depression more severe (mean Geriatric Depression Scale score of 2.8 versus 1.4, P = 0.006) in mildly symptomatic mutation carriers relative to non-carriers. Anxiety, appetite changes, delusions, and repetitive motor activity were additionally more common in overtly impaired mutation carriers. Similar to studies of late-onset Alzheimer's disease, we demonstrated increased rates of depression, apathy, and other behavioural symptoms in the mildly symptomatic, prodromal phase of autosomal dominant Alzheimer's disease that increased with disease severity. We did not identify any increased psychopathology in mutation carriers over non-carriers during the presymptomatic stage, suggesting these symptoms result when a threshold of neurodegeneration is reached rather than as life-long qualities. Unexpectedly, we found lower rates of depressive symptoms in cognitively asymptomatic mutation carriers.
Brain arteriolosclerosis (B-ASC) is characterized by pathologically altered brain parenchymal arterioles. B-ASC is associated with cognitive impairment and increased likelihood of clinical dementia. ...To date, no study has been conducted on genome-wide genetic risk of autopsy-proven B-ASC. We performed a genome-wide association study (GWAS) of the B-ASC phenotype using multiple independent aged neuropathologic cohorts. Included in the study were participants with B-ASC autopsy and genotype data available from the NACC, ROSMAP, ADNI, and ACT data sets. Initial Stage 1 GWAS (n = 3382) and Stage 2 mega-analysis (n = 4569) were performed using data from the two largest cohorts (NACC and ROSMAP). Replication of top variants and additional Stage 3 mega-analysis were performed incorporating two smaller cohorts (ADNI and ACT). Lead variants in the top two loci in the Stage 2 mega-analysis (rs7902929, p =
1.8
×
10
−
7
; rs2603462, p =
4
×
10
−
7
) were significant in the ADNI cohort (rs7902929, p =
0.012
; rs2603462, p =
0.012
). The rs2603462 lead variant colocalized with ELOVL4 expression in the cerebellum (posterior probability = 90.1%). Suggestive associations were also found near SORCS1 and SORCS3. We thus identified putative loci associated with B-ASC risk, but additional replication is needed.
IMPORTANCE: Mutations in APP, PSEN1, and PSEN2 lead to early-onset Alzheimer disease (EOAD) but account for only approximately 11% of EOAD overall, leaving most of the genetic risk for the most ...severe form of Alzheimer disease unexplained. This extreme phenotype likely harbors highly penetrant risk variants, making it primed for discovery of novel risk genes and pathways for AD. OBJECTIVE: To search for rare variants contributing to the risk for EOAD. DESIGN, SETTING, AND PARTICIPANTS: In this case-control study, whole-exome sequencing (WES) was performed in 51 non-Hispanic white (NHW) patients with EOAD (age at onset <65 years) and 19 Caribbean Hispanic families previously screened as negative for established APP, PSEN1, and PSEN2 causal variants. Participants were recruited from John P. Hussman Institute for Human Genomics, Case Western Reserve University, and Columbia University. Rare, deleterious, nonsynonymous, or loss-of-function variants were filtered to identify variants in known and suspected AD genes, variants in multiple unrelated NHW patients, variants present in 19 Hispanic EOAD WES families, and genes with variants in multiple unrelated NHW patients. These variants/genes were tested for association in an independent cohort of 1524 patients with EOAD, 7046 patients with late-onset AD (LOAD), and 7001 cognitively intact controls (age at examination, >65 years) from the Alzheimer’s Disease Genetics Consortium. The study was conducted from January 21, 2013, to October 13, 2016. MAIN OUTCOMES AND MEASURES: Alzheimer disease diagnosed according to standard National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer Disease and Related Disorders Association criteria. Association between Alzheimer disease and genetic variants and genes was measured using logistic regression and sequence kernel association test–optimal gene tests, respectively. RESULTS: Of the 1524 NHW patients with EOAD, 765 (50.2%) were women and mean (SD) age was 60.0 (4.9) years; of the 7046 NHW patients with LOAD, 4171 (59.2%) were women and mean (SD) age was 77.4 (8.6) years; and of the 7001 NHW controls, 4215 (60.2%) were women and mean (SD) age was 77.4 (8.6) years. The gene PSD2, for which multiple unrelated NHW cases had rare missense variants, was significantly associated with EOAD (P = 2.05 × 10−6; Bonferroni-corrected P value BP = 1.3 × 10−3) and LOAD (P = 6.22 × 10−6; BP = 4.1 × 10−3). A missense variant in TCIRG1, present in a NHW patient and segregating in 3 cases of a Hispanic family, was more frequent in EOAD cases (odds ratio OR, 2.13; 95% CI, 0.99-4.55; P = .06; BP = 0.413), and significantly associated with LOAD (OR, 2.23; 95% CI, 1.37-3.62; P = 7.2 × 10−4; BP = 5.0 × 10−3). A missense variant in the LOAD risk gene RIN3 showed suggestive evidence of association with EOAD after Bonferroni correction (OR, 4.56; 95% CI, 1.26-16.48; P = .02, BP = 0.091). In addition, a missense variant in RUFY1 identified in 2 NHW EOAD cases showed suggestive evidence of an association with EOAD as well (OR, 18.63; 95% CI, 1.62-213.45; P = .003; BP = 0.129). CONCLUSIONS AND RELEVANCE: The genes PSD2, TCIRG1, RIN3, and RUFY1 all may be involved in endolysosomal transport—a process known to be important to development of AD. Furthermore, this study identified shared risk genes between EOAD and LOAD similar to previously reported genes, such as SORL1, PSEN2, and TREM2.
Background
This study used admixture mapping to prioritize the genetic regions associated with Alzheimer's disease (AD) in African American (AA) individuals, followed by ancestry‐aware regression ...analysis to fine‐map the prioritized regions.
Methods
We analyzed 10,271 individuals from 17 different AA datasets. We performed admixture mapping and meta‐analyzed the results. We then used regression analysis, adjusting for local ancestry main effects and interactions with genotype, to refine the regions identified from admixture mapping. Finally, we leveraged in silico annotation and differential gene expression data to prioritize AD‐related variants and genes.
Results
Admixture mapping identified two genome‐wide significant loci on chromosomes 17p13.2 (p = 2.2 × 10−5) and 18q21.33 (p = 1.2 × 10−5). Our fine mapping of the chromosome 17p13.2 and 18q21.33 regions revealed several interesting genes such as the MINK1, KIF1C, and BCL2.
Discussion
Our ancestry‐aware regression approach showed that AA individuals have a lower risk of AD if they inherited African ancestry admixture block at the 17p13.2 locus.
Highlights
We identified two genome‐wide significant admixture mapping signals: on chromosomes 17p13.2 and 18q21.33, which are novel in African American (AA) populations.
Our ancestry‐aware regression approach showed that AA individuals have a lower risk of Alzheimer's disease (AD) if they inherited African ancestry admixture block at the 17p13.2 locus.
We found that the overall proportion of African ancestry does not differ between the cases and controls that suggest African genetic ancestry alone is not likely to explain the AD prevalence difference between AA and non‐Hispanic White populations.
•A genome-wide significant linkage peak (HLOD=5.1) on 9p21 was found in PR Families for AD.•A rare missense variant in UNC13B segregates within PR families and is associated with AD risk in an ...independent case-control PR WGS dataset.•Our study demonstrated the importance of family-based design and WGS in genetic study of AD.
The genetic admixture of Caribbean Hispanics provides an opportunity to discover novel genetic factors in Alzheimer disease (AD). We sought to identify genetic variants for AD through a family-based design using the Puerto Rican (PR) Alzheimer Disease Initiative (PRADI). Whole-genome sequencing (WGS) and parametric linkage analysis were performed for 100 individuals from 23 multiplex PRADI families. Variants were prioritized by minor allele frequency (<0.01), functional potential combined annotation dependent depletion score (CADD) >10, and co-segregation with AD. Variants were further ranked using an independent PR case-control WGS dataset (PR10/66). A genome-wide significant linkage peak was found in 9p21 with a heterogeneity logarithm of the odds score (HLOD) >5.1, which overlaps with an AD linkage region from two published independent studies. The region harbors C9orf72, but no expanded repeats were observed in the families. Seven variants prioritized by the PRADI families also displayed evidence for association in the PR10/66 (p < 0.05), including a missense variant in UNC13B. Our study demonstrated the importance of family-based design and WGS in genetic study of AD.
INTRODUCTION
Although large‐scale genome‐wide association studies (GWAS) have been conducted on AD, few have been conducted on continuous measures of memory performance and memory decline.
METHODS
We ...conducted a cross‐ancestry GWAS on memory performance (in 27,633 participants) and memory decline (in 22,365 participants; 129,201 observations) by leveraging harmonized cognitive data from four aging cohorts.
RESULTS
We found high heritability for two ancestry backgrounds. Further, we found a novel ancestry locus for memory decline on chromosome 4 (rs6848524) and three loci in the non‐Hispanic Black ancestry group for memory performance on chromosomes 2 (rs111471504), 7 (rs4142249), and 15 (rs74381744). In our gene‐level analysis, we found novel genes for memory decline on chromosomes 1 (SLC25A44), 11 (BSX), and 15 (DPP8). Memory performance and memory decline shared genetic architecture with AD‐related traits, neuropsychiatric traits, and autoimmune traits.
DISCUSSION
We discovered several novel loci, genes, and genetic correlations associated with late‐life memory performance and decline.
Highlights
Late‐life memory has high heritability that is similar across ancestries.
We discovered four novel variants associated with late‐life memory.
We identified four novel genes associated with late‐life memory.
Late‐life memory shares genetic architecture with psychiatric/autoimmune traits.
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