The Minority Aging Research Study: ongoing efforts to obtain brain donation in African Americans without dementia

Limbic-predominant age-related TDP-43 encephalopathy neuropathological change (LATE-NC) is associated with abnormalities in white matter structural integrity and connectivity: An ex-vivo diffusion MRI and pathology investigation

Limbic predominant age-related TDP-43 encephalopathy neuropathological change (LATE-NC) is common in older adults and is associated with neurodegeneration, cognitive decline and dementia. In this MRI and pathology investigation we tested the hypothesis that LATE-NC is associated with abnormalities in white matter structural integrity and connectivity of a network of brain regions typically harboring TDP-43 inclusions in LATE, referred to here as the "LATE-NC network". Ex-vivo diffusion MRI and detailed neuropathological data were collected on 184 community-based older adults. Linear regression revealed an independent association of higher LATE-NC stage with lower diffusion anisotropy in a set of white matter connections forming a pattern of connectivity that is consistent with the stereotypical spread of this pathology in the brain. Graph theory analysis revealed an association of higher LATE-NC stage with weaker integration and segregation in the LATE-NC network. Abnormalities were significant in stage 3, suggesting that they are detectable in later stages of the disease. Finally, LATE-NC network abnormalities were associated with faster cognitive decline, specifically in episodic and semantic memory.

Racial differences in the effect of verbal and nonverbal memory on concrete planning for future care needs among older adults: a multi-group structural equation modeling approach

Concrete planning for future care needs may positively impact older adults' subsequent mental health and quality of life. However, the cognitive factors that facilitate concrete planning among Black and White older adults are still poorly understood. We investigated whether there are significant differences between Black (n = 159) and White (n = 262) older adults in concrete planning and explored racial differences in the relationship between verbal and nonverbal episodic memory and concrete planning. Results revealed that Blacks showed lower engagement in concrete planning and lower scores than Whites on each verbal and nonverbal memory task. For Blacks, but not Whites, verbal memory and nonverbal memory performance predicted concrete planning with higher nonverbal memory relating to less concrete planning and higher verbal memory associated with more concrete planning. Our findings suggest racial differences exist in how episodic verbal and nonverbal memory affect concrete planning, a crucial factor for older adults' preparation for future care.

Overcoming Pandemic-Related Challenges in Recruitment and Screening: Strategies and Representation of Older Women With Cardiovascular Disease for a Multidomain Lifestyle Trial to Prevent Cognitive Decline

BACKGROUND

Recruiting participants with cardiovascular disease into research during the COVID-19 pandemic was challenging, particularly those at risk of health disparities.

OBJECTIVE

During the pandemic, 12 cohorts of older women with cardiovascular disease were recruited from cardiology clinics into a lifestyle intervention trial to prevent cognitive decline. Objectives were to ( a ) describe the results of modified recruitment/screening strategies to overcome pandemic-related challenges and ( b ) evaluate differences in age, race, and ethnicity between patients recruited/randomized, recruited/not randomized (entered recruitment but not randomized because of being ineligible or not interested), and not recruited (clinic patients who met preliminary criteria but did not enter recruitment).

METHODS

This was a cross-sectional descriptive analysis. In-person study strategies proposed before the COVID-19 pandemic were modified before study onset (September 2020). Women 65 years or older with cardiovascular disease were recruited from cardiology clinics by clinicians, posted flyers, and letters mailed to patients randomly selected from electronic health record data extractions. Patients were classified as recruited/randomized, recruited/not randomized, and not recruited.

RESULTS

Of 5719 patients potentially eligible, 1689 patients entered recruitment via referral (49.1%), posted flyers (0.5%), or mailed letters (50.3%), and 253 patients were successfully recruited/randomized. Recruited/randomized participants were, on average, 72.4 years old (range, 65-90 years old), non-Hispanic White (54.2%), non-Hispanic Black (38.3%), Hispanic/Latinx (1.6%), and other/not reported (5.1%). The recruited/randomized group was significantly younger with fewer patients of Hispanic/Latinx ethnicity compared with those not recruited.

CONCLUSIONS

During the pandemic, all recruitment/screening goals were met using modified strategies. Differences in sociodemographic representation indicate a need for tailored strategies.

Correlates of missed or late versus timely diagnosis of dementia in healthcare settings

INTRODUCTION

There is limited evidence about factors related to the timeliness of dementia diagnosis in healthcare settings.

METHODS

In five prospective cohorts at Rush Alzheimer's Disease Center, we identified participants with incident dementia based on annual assessments and examined the timing of healthcare diagnoses in Medicare claims. We assessed sociodemographic, health, and psychosocial correlates of timely diagnosis.

RESULTS

Of 710 participants, 385 (or 54%) received a timely claims diagnosis within 3 years prior to or 1 year following dementia onset. In logistic regressions accounting for demographics, we found Black participants (odds ratio [OR] = 2.15, 95% confidence interval [CI]: 1.21 to 3.82) and those with better cognition at dementia onset (OR = 1.48, 95% CI: 1.10 to 1.98) were at higher odds of experiencing a diagnostic delay, whereas participants with higher income (OR = 0.89, 95% CI: 0.81 to 0.97) and more comorbidities (OR = 0.94, 95% CI: 0.89 to 0.98) had lower odds.

DISCUSSION

We identified characteristics of individuals who may miss the optimal window for dementia treatment and support.

HIGHLIGHTS

We compared the timing of healthcare diagnosis relative to the timing of incident dementia based on rigorous annual evaluation. Older Black adults with lower income, higher cognitive function, and fewer comorbidities were less likely to be diagnosed in a timely manner by the healthcare system.

Sex, racial, and APOE-ε4 allele differences in longitudinal white matter microstructure in multiple cohorts of aging and Alzheimer's disease

INTRODUCTION

The effects of sex, race, and Apolipoprotein E (APOE) - Alzheimer's disease (AD) risk factors - on white matter integrity are not well characterized.

METHODS

Diffusion MRI data from nine well-established longitudinal cohorts of aging were free-water (FW)-corrected and harmonized. This dataset included 4,702 participants (age=73.06 ± 9.75) with 9,671 imaging sessions over time. FW and FW-corrected fractional anisotropy (FAFWcorr) were used to assess differences in white matter microstructure by sex, race, and APOE-ε4 carrier status.

RESULTS

Sex differences in FAFWcorr in association and projection tracts, racial differences in FAFWcorr in projection tracts, and APOE-ε4 differences in FW limbic and occipital transcallosal tracts were most pronounced.

DISCUSSION

There are prominent differences in white matter microstructure by sex, race, and APOE-ε4 carrier status. This work adds to our understanding of disparities in AD. Additional work to understand the etiology of these differences is warranted.

The influence of APOE status on rate of cognitive decline

BACKGROUND

Apolipoprotein (APOE) ɛ4 positivity and subjective cognitive decline (SCD) both increase risk of Alzheimer's disease (AD) development. However, few studies have examined the relationship between SCD and APOE status, especially using longitudinal data. The current study examined whether APOE is associated with the rate of cognitive change in SCD and mild cognitive impairment (MCI).

METHODS

A sample of 3494 older adults (1990 normal controls, NC, 775 SCD, and 729 MCI) with a mean follow-up of 9.09 years were included from the Rush Alzheimer's Disease Center Research Sharing Hub. Linear mixed effects models examined the relationship between APOE status and cognitive change in older adults with SCD normal controls, and people with MCI.

RESULTS

The presence of at least one ɛ2 allele in SCD and MCI results in cognitive change rates similar to a NC with the ɛ3ɛ3 genotype. Older adult SCD-ɛ4 individuals exhibited increased rate of cognitive decline compared to all groups, including NC-ɛ4 and MCI-ɛ4.

CONCLUSION

People with SCD with at least one ɛ4 allele experience increased rates of cognitive decline compared to cognitively healthy older adults and people with MCI. These findings have important implications for treatments and interventions and can improve future research and clinical trials by targeting people in the preclinical AD phase (i.e., SCD) who also possess at least one APOE ɛ4 allele.

Pioneering a Multi-Phase Framework to Harmonize Self-Reported Sleep Data Across Cohorts

STUDY OBJECTIVES

Harmonizing and aggregating data across studies enable pooled analyses that support external validation and enhance replicability and generalizability. However, the multidimensional nature of sleep poses challenges for data harmonization and aggregation. Here we describe and implement our process for harmonizing self-reported sleep data.

METHODS

We established a multi-phase framework to harmonize self-reported sleep data: (1) compile items; (2) group items into domains; (3) harmonize items; and (4) evaluate harmonizability. We applied this process to produce a pooled multi-cohort sample of five United States cohorts plus a separate yet fully harmonized sample from Rotterdam, Netherlands. Sleep and sociodemographic data are described and compared to demonstrate the utility of harmonization and aggregation.

RESULTS

We collected 190 unique self-reported sleep items and grouped them into 15 conceptual domains. Using these domains as guiderails, we developed 14 harmonized items measuring aspects of Satisfaction, Alertness/Sleepiness, Timing, Efficiency, Duration, Insomnia, and Sleep Apnea. External raters determined that 13 of these 14 items had moderate-to-high harmonizability. Alertness/Sleepiness items had lower harmonizability, while continuous, quantitative items (e.g., timing, total sleep time, efficiency) had higher harmonizability. Descriptive statistics identified features that are more consistent (e.g., wake-up time, duration) and more heterogeneous (e.g., time in bed, bedtime) across samples.

CONCLUSIONS

Our process can guide researchers and cohort stewards towards effective sleep harmonization and provides a foundation for further methodological development in this expanding field. Broader national and international initiatives promoting common data elements across cohorts are needed to enhance future harmonization and aggregation efforts.

The time course of motor and cognitive decline in older adults and their associations with brain pathologies: a multicohort study

BACKGROUND

Many studies have reported that impaired gait precedes cognitive impairment in older people. We aimed to characterise the time course of cognitive and motor decline in older individuals and the association of these declines with the pathologies of Alzheimer's disease and related dementias.

METHODS

This multicohort study used data from three community-based cohort studies (Religious Orders Study, Rush Memory and Aging Project, and Minority Aging Research Study, all in the USA). The inclusion criteria for all three cohorts were no clinical dementia at the time of enrolment and consent to annual clinical assessments. Eligible participants consented to post-mortem brain donation and had post-mortem pathological assessments and three or more repeated annual measures of cognition and motor functions. Clinical and post-mortem data were analysed using functional mixed-effects models. Global cognition was based on 19 neuropsychological tests, a hand strength score was based on grip and pinch strength, and a gait score was based on the number of steps and time to walk 8 feet and turn 360°. Brain pathologies of Alzheimer's disease and related dementias were assessed at autopsy.

FINDINGS

From 1994 to 2022, there were 1570 eligible cohort participants aged 65 years or older, 1303 of whom had cognitive and motor measurements and were included in the analysis. Mean age at death was 90·3 years (SD 6·3), 905 (69%) participants were female, and 398 (31%) were male. Median follow-up time was 9 years (IQR 5-11). On average, cognition was stable from 25 to 15 years before death, when cognition began to decline. By contrast, gait function and hand strength declined during the entire study. The combinations of pathologies of Alzheimer's disease and related dementias associated with cognitive and motor decline and their onsets of associations varied; only tau tangles, Parkinson's disease pathology, and macroinfarcts were associated with decline of all three phenotypes. Tau tangles were significantly associated with cognitive decline, gait function decline, and hand function decline (p<0·0001 for each); however, the association with cognitive decline persisted for more than 11 years before death, but the association with hand strength only began 3·57 years before death and the association with gait began 3·49 years before death. By contrast, the association of macroinfarcts with declining gait function began 9·25 years before death (p<0·0001) compared with 6·65 years before death (p=0·0005) for cognitive decline and 2·66 years before death (p=0·024) for decline in hand strength.

INTERPRETATION

Our findings suggest that average motor decline in older adults precedes cognitive decline. Macroinfarcts but not tau tangles are associated with declining gait function that precedes cognitive decline. This suggests the need for further studies to test if gait impairment is a clinical proxy for preclinical vascular cognitive impairment.

FUNDING

National Institutes of Health.

Everyday Discrimination Is Associated With Higher Odds of Hospitalizations Among Older African Americans

BACKGROUND

Everyday discrimination-experiences of being treated unfairly based on background characteristics like race-is linked to poor physical and mental health throughout the lifespan. Whether more experiences of discrimination are associated with higher odds of being hospitalized in older African Americans has not been explored.

METHODS

Community-dwelling participants from 3 longitudinal cohort studies (N = 446, age 65+ years) with discrimination scores and ≥12 months of linked Medicare claims were included. Hospitalizations were identified using Medicare fee-for-service claims, available for an average of 6.2 (SD: 3.7) years of follow-up after baseline.

RESULTS

In mixed-effects ordinal logistic regression models (outcomes of 0, 1, or 2+ hospitalizations per year) adjusted for age, sex, education, and income, higher discrimination was associated with higher odds of total annual hospitalizations (odds ratio [OR] per point higher = 1.09, 95% confidence intervals [95% CI]: 1.02-1.17). Results were similar when accounting for depressive symptoms.

CONCLUSIONS

Higher exposure to everyday discrimination is associated with higher odds of hospitalization among older African Americans. Mechanisms underlying associations should be explored further to understand how hospitalizations may be reduced in older African Americans.

Bridging the Gap: Multi-Omics Profiling of Brain Tissue in Alzheimer's Disease and Older Controls in Multi-Ethnic Populations

INTRODUCTION

Multi-omics studies in Alzheimer's disease (AD) revealed many potential disease pathways and therapeutic targets. Despite their promise of precision medicine, these studies lacked African Americans (AA) and Latin Americans (LA), who are disproportionately affected by AD.

METHODS

To bridge this gap, Accelerating Medicines Partnership in AD (AMP-AD) expanded brain multi-omics profiling to multi-ethnic donors.

RESULTS

We generated multi-omics data and curated and harmonized phenotypic data from AA (n=306), LA (n=326), or AA and LA (n=4) brain donors plus Non-Hispanic White (n=252) and other (n=20) ethnic groups, to establish a foundational dataset enriched for AA and LA participants. This study describes the data available to the research community, including transcriptome from three brain regions, whole genome sequence, and proteome measures.

DISCUSSION

Inclusion of traditionally underrepresented groups in multi-omics studies is essential to discover the full spectrum of precision medicine targets that will be pertinent to all populations affected with AD.

Recruiting a prospective community cohort to study Alzheimer's disease and structural and social determinants of health among adults racialized as Black: The ARCHES cohort

INTRODUCTION

This ongoing, prospective study examines the effectiveness of methods used to successfully recruit and retain 238 Black older adults in a longitudinal, observational Alzheimer's disease (AD) study.

METHODS

Recruitment strategies included traditional media, established research registries, speaking engagements, community events, and snowball sampling. Participants were asked to complete an annual office testing session, blood-based biomarker collection, optional one-time magnetic resonance imaging (MRI) scan, and community workshop.

RESULTS

Within the first 22 months of active recruitment, 629 individuals expressed interest in participating, and 238 enrolled in the ongoing study. Of the recruitment methods used, snowball sampling, community events, and speaking engagements were the most effective.

DISCUSSION

The systemic underrepresentation of Black participants in AD research impacts the ability to generalize research findings and determine the effectiveness and safety of disease-modifying treatments. Research to slow, stop, or prevent AD remains a top priority but requires diversity in sample representation.

Highlights

Provide flexible appointments in the evening or weekends, offering transportation assistance, and allowing participants to complete study visits at alternative locations, such as senior centers or community centers.Continuously monitor and analyze recruitment data to identify trends, challenges, and opportunities for improvement.Implement targeted strategies to recruit participants who are underrepresented based on sex, gender, or education to increase representation.Diversify the research team to include members who reflect the racial and cultural backgrounds of the target population, to enhance trust and rapport with prospective participants.

Changes in Body Mass Index and Incident Mild Cognitive Impairment Among African American Older Adults

BACKGROUND

Previous research suggests a decline in body mass index (BMI) among older adults is associated with negative health outcomes, including mild cognitive impairment (MCI) and incident dementia. However, no studies have examined the effects of education or developing MCI on BMI trajectories over time. The purpose of this investigation was to characterize trajectories of change in BMI among older adults who develop MCI.

METHODS

Participants were from the Minority Aging Research Study (MARS), a longitudinal cohort study of cognitive decline and Alzheimer's disease in older African Americans living in the greater Chicago, Illinois, area. The study included annual clinical evaluations of cognitive status, as well as measurements of height and weight for BMI calculation. Older African American participants without cognitive impairment at baseline were included in the present analysis (N = 436, 78% women, mean baseline age = 72 [SD = 5.7], mean education = 15 [SD = 3.5]).

RESULTS

In piecewise linear mixed-effects models that included a random intercept and 2 random slopes, BMI declined over time (B = -0.20, SE = 0.02, p < .001), with a faster decline after MCI diagnosis (additional decline, B = -0.15, SE = 0.06, p = .019). Older age was associated with lower baseline BMI (B = -0.19, SE = 0.05, p < .001), as was higher education (B = -0.34, SE = 0.09, p < .001). Further, higher education was associated with a slower decline in BMI before MCI (B = 0.02, SE = 0.006, p = .001), but a faster decline after MCI (B = -0.06, SE = 0.022, p = .003).

CONCLUSIONS

These results suggest an accelerated decline in BMI following an MCI diagnosis, with higher education related to an even faster BMI decline.

Meeting report of the fifth annual workshop on Principles and Techniques for Improving Preclinical to Clinical Translation in Alzheimer's Disease Research

The fifth annual workshop on Principles and Techniques for Improving Preclinical Translation of Alzheimer's Disease Research was held in May 2023 at The Jackson Laboratory in Bar Harbor, Maine, USA. The workshop was established in 2018 to address training gaps in preclinical translational studies for Alzheimer's disease (AD). In addition to providing fundamental knowledge and hands-on skills essential for executing rigorous in vivo studies that are designed to facilitate translation, each year the workshop aims to provide insight on state-of-the-field technological advances and new resources including novel animal models, publicly available datasets, novel biomarkers, and new medical imaging tracers. This innovative and comprehensive workshop continues to deliver training for the greater AD research community in order to provide investigators and trainees with the knowledge and skillsets essential for enabling improved preclinical to clinical translation and accelerate the process of advancing safe and effective therapeutic interventions for AD. HIGHLIGHTS: Translational research is not typically available as a course of study at academic institutions, yet there are fundamental skillsets and knowledge required to enable successful translation from preclinical experiments to clinical efficacy. It is important that there are resources and opportunities available to researchers planning preclinical translational experiments. Here we present proceedings from the fifth annual NIA-sponsored workshop focused on enabling improved preclinical to clinical translation for Alzheimer's disease research that includes didactic lectures on state-of-the-field approaches and hands-on practicums for acquiring essential translational laboratory techniques.

Chronic traumatic encephalopathy and aging-related tau astrogliopathy in community-dwelling older persons with and without moderate-to-severe traumatic brain injury

This study examined the frequency of chronic traumatic encephalopathy-neuropathologic change (CTE-NC) and aging-related tau astrogliopathy (ARTAG) in community-dwelling older adults and tested the hypothesis that these tau pathologies are associated with a history of moderate-to-severe traumatic brain injury (msTBI), defined as a TBI with loss of consciousness >30 minutes. We evaluated CTE-NC, ARTAG, and Alzheimer disease pathologies in 94 participants with msTBI and 94 participants without TBI matched by age, sex, education, and dementia status TBI from the Rush community-based cohorts. Six (3%) of brains showed the pathognomonic lesion of CTE-NC; only 3 of these had a history of msTBI. In contrast, ARTAG was common in older brains (gray matter ARTAG = 77%; white matter ARTAG = 54%; subpial ARTAG = 51%); there were no differences in severity, type, or distribution of ARTAG pathology with respect to history of msTBI. Furthermore, those with msTBI did not have higher levels of PHF-tau tangles density but had higher levels of amyloid-β load (Estimate = 0.339, SE = 0.164, p = 0.040). These findings suggest that CTE-NC is infrequent while ARTAG is common in the community and that both pathologies are unrelated to msTBI. The association of msTBI with amyloid-β, rather than with tauopathies suggests differential mechanisms of neurodegeneration in msTBI.

Changes in an in-vivo classifier of ARTerioloSclerosis (ARTS) with simultaneous change in cognition for older African Americans

At autopsy, African American decedents often have mixed Alzheimer's and cerebrovascular brain pathologies including arteriolosclerosis. We applied a novel in-vivo classifier of ARTerioloSclerosis (ARTS) in 167 older African Americans (∼75y of age) with > 2 biennial 3 T MRI scans and > 3 years of associated cognitive follow-up to determine if ARTS scores (higher score=higher likelihood of arteriolosclerosis) changed over time and if this change associated with changes in cognition in the same individuals. Mixed effects regression models tested whether ARTS scores increased over time, while simultaneous mixed effects regression models estimated the simultaneous rates of change in both ARTS and cognition and the correlation of these changes. ARTS scores increased over time (estimate=0.030, SE=0.002, p < 0.0001). Faster increases in ARTS were associated with faster rates of global cognitive decline (r = -0.447, p = 0.006) and domain-specific cognitive functions. Applying an in-vivo marker of arteriolosclerosis in an African American cohort revealed that the likelihood of arteriolosclerosis increases over time, and participants whose ARTS scores increased more rapidly tended to have faster than average rates of cognitive decline.

Sex-specific genetic architecture of late-life memory performance

BACKGROUND

Women demonstrate a memory advantage when cognitively healthy yet lose this advantage to men in Alzheimer's disease. However, the genetic underpinnings of this sex difference in memory performance remain unclear.

METHODS

We conducted the largest sex-aware genetic study on late-life memory to date (Nmales  = 11,942; Nfemales  = 15,641). Leveraging harmonized memory composite scores from four cohorts of cognitive aging and AD, we performed sex-stratified and sex-interaction genome-wide association studies in 24,216 non-Hispanic White and 3367 non-Hispanic Black participants.

RESULTS

We identified three sex-specific loci (rs67099044-CBLN2, rs719070-SCHIP1/IQCJ-SCHIP), including an X-chromosome locus (rs5935633-EGL6/TCEANC/OFD1), that associated with memory. Additionally, we identified heparan sulfate signaling as a sex-specific pathway and found sex-specific genetic correlations between memory and cardiovascular, immune, and education traits.

DISCUSSION

This study showed memory is highly and comparably heritable across sexes, as well as highlighted novel sex-specific genes, pathways, and genetic correlations that related to late-life memory.

HIGHLIGHTS

Demonstrated the heritable component of late-life memory is similar across sexes. Identified two genetic loci with a sex-interaction with baseline memory. Identified an X-chromosome locus associated with memory decline in females. Highlighted sex-specific candidate genes and pathways associated with memory. Revealed sex-specific shared genetic architecture between memory and complex traits.

Untangling a taxonomy of living from the science of the continuum of life

Medical innovation and technologic advances enrich daily living and occur within our normative worlds, that are socially constructed. These advances confront society with critical questions about the nature of human life, laying bare the inadequacies of extant norms and boundaries. Yet, society has been unable to develop consensus about when life ends. Scientific studies highlight that life is best characterized by continua without natural boundaries. Thus, scientific information alone cannot be employed to justify the socially constructed health categories required for setting norms and boundaries. An iterative process that integrates a broad range of non-scientific data with advancing scientific information is needed to facilitate consensus for updating social norms and boundaries. This can lead to a new taxonomy of living across the measurable continuum of life and align our normative worlds with the dizzying pace of medical innovation and advances in technologies transforming the world in which we live.

Longitudinal change in memory performance as a strong endophenotype for Alzheimer's disease

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.

Financial Risk Aversion Among Older Black and White Adults

OBJECTIVES

Risk aversion has a substantial impact on decision making and is associated with key demographic characteristics. However, few studies have investigated whether risk aversion varies by race.

METHODS

We investigated racial differences in financial risk aversion in 684 older Black and White adults without dementia in the Minority Aging Research Study and Rush Memory and Aging Project matched for age, education, sex, and cognition using Mahalanobis distance. We also investigated whether select contextual factors (self-reported discrimination, socioeconomic status, and literacy) mediated or affective factors (trust, loneliness, and neuroticism) moderated any observed racial differences.

RESULTS

In regression models adjusted for age, education, sex, and cognitive function, older Black adults were more risk averse than older White adults (Beta = 0.1264, standard error = 0.0227, p value ≤ .00001). None of the contextual or affective factors mediated or moderated this association.

DISCUSSION

Older Black adults are more financially risk averse than older White adults. Because risk aversion may be associated with important financial and health outcomes in older age, more research is needed to investigate the reasons for this difference.

Beyond Hypertension: Examining Variable Blood Pressure's Role in Cognition and Brain Structure

Importance

Hypertension is a known risk factor for cognitive decline and structural brain changes in aging and dementia. In addition to high blood pressure (BP), individuals may also experience variable BP, meaning that their BP fluctuates between normal and high. It is currently unclear what the effects of variable BP are on cognition and brain structure.

Objective

To investigate the influence of BP on cognition and brain structure in older adults.

Design Setting and Participants

This longitudinal cohort study included data from the Rush Alzheimer's Disease Center Research Resource Sharing Hub (RUSH) and the Alzheimer's Disease Neuroimaging Initiative (ADNI). Participants from the two studies were included if they had BP measurements and either cognitive scores or MRI scans from at least one visit.

Main Outcomes and Measures

Longitudinal gray matter, white matter, white matter hyperintensity volumes, postmortem neuropathology information, as well as cognitive test scores.

Results

A total of 4606 participants (3429 females, mean age = 76.8) with 32776 follow-ups (mean = 7 years) from RUSH and 2114 participants (1132 females, mean age = 73.3) with 9827 follow-ups (mean = 3 years) from ADNI were included in this study. Participants were divided into one of three groups: 1) normal BP, high BP, or variable BP. Older adults with variable BP exhibited the highest rate of cognitive decline followed by high BP and then normal BP. Increased GM volume loss and WMH burden was also observed in variable BP compared to high and normal BP. With respect to post-mortem neuropathology, both variable and high BP had increased severities compared to normal BP. Importantly, results were consistent across the RUSH and ADNI participants, supporting the generalizability of the findings.

Conclusion and Relevance

Limited research has examined the long-term impact of variable BP on cognition and brain structure. These findings show the importance that both high and variable BP have on cognitive decline and structural brain changes. Structural damages caused by variable BP may reduce resilience to future dementia-related pathology and increased risk of dementia. Improved treatment and management of variable BP may help reduce cognitive decline in the older adult population.

Estimating dementia risk in an African American population using the DCTclock

The prevalence of Alzheimer's disease (AD) and related dementias (ADRD) is increasing. African Americans are twice as likely to develop dementia than other ethnic populations. Traditional cognitive screening solutions lack the sensitivity to independently identify individuals at risk for cognitive decline. The DCTclock is a 3-min AI-enabled adaptation of the well-established clock drawing test. The DCTclock can estimate dementia risk for both general cognitive impairment and the presence of AD pathology. Here we performed a retrospective analysis to assess the performance of the DCTclock to estimate future conversion to ADRD in African American participants from the Rush Alzheimer's Disease Research Center Minority Aging Research Study (MARS) and African American Clinical Core (AACORE). We assessed baseline DCTclock scores in 646 participants (baseline median age = 78.0 ± 6.4, median years of education = 14.0 ± 3.2, 78% female) and found significantly lower baseline DCTclock scores in those who received a dementia diagnosis within 3 years. We also found that 16.4% of participants with a baseline DCTclock score less than 60 were significantly more likely to develop dementia in 5 years vs. those with the highest DCTclock scores (75-100). This research demonstrates the DCTclock's ability to estimate the 5-year risk of developing dementia in an African American population. Early detection of elevated dementia risk using the DCTclock could provide patients, caregivers, and clinicians opportunities to plan and intervene early to improve cognitive health trajectories. Early detection of dementia risk can also enhance participant selection in clinical trials while reducing screening costs.

Profiles of lifestyle health behaviors and cognitive decline in older adults

INTRODUCTION

We aimed to identify profiles of modifiable, late-life lifestyle health behaviors related to subsequent maintenance of cognition and explore sociodemographics and health characteristics as effect modifiers.

METHODS

Analyses used data from 715 older adults without baseline dementia from the Rush Memory and Aging Project and with lifestyle health behaviors (physical activity, cognitive activity, healthy diet, social activity) at baseline and ≥ 2 annual assessments of cognition. We used latent profile analysis to group participants based on behavior patterns and assessed change in cognition by group.

RESULTS

Three latent profiles were identified: high (n = 183), moderate (n = 441), and low (n = 91) engagement in health behaviors. Compared to high engagement, the moderate (mean difference [MD] = -0.02, 95% CI = [-0.03;-0.0002], p = 0.048) and low (MD = -0.06, 95% CI = [-0.08;-0.03], p < 0.0001) groups had faster annual rates of decline in global cognition, with no significant effects modifiers (vascular risk factors, apolipoprotein E [APOE] ε4, motor function).

DISCUSSION

Avoiding low levels of lifestyle health behaviors may help maintain cognition.

HIGHLIGHTS

Latent profile analysis (LPA) captures lifestyle health behaviors associated with cognitive function. Such behavior include physical activity, cognitive activity, healthy diet, social activity. We used LPA to examine associations of behaviors and cognitive function over time. Older adults with low lifestyle health behaviors showed more rapid decline. To a lesser degree, so did those with moderate lifestyle health behaviors. Vascular conditions and risks, APOEε4, or motor function did not modify the effect.

Cerebral Small Vessel Disease, Hypertension, and Vascular Contributions to Cognitive Impairment and Dementia

Hypertension-associated cerebral small vessel disease is a common finding in older people. Strongly associated with age and hypertension, small vessel disease is found at autopsy in over 50% of people aged ≥65 years, with a spectrum of clinical manifestations. It is the main cause of lacunar stroke and a major source of vascular contributions to cognitive impairment and dementia. The brain areas affected are subcortical and periventricular white matter and deep gray nuclei. Neuropathological sequelae are diffuse white matter lesions (seen as white matter hyperintensities on T2-weighted magnetic resonance imaging), small ischemic foci (lacunes or microinfarcts), and less commonly, subcortical microhemorrhages. The most common form of cerebral small vessel disease is concentric, fibrotic thickening of small penetrating arteries (up to 300 microns outer diameter) termed arteriolosclerosis. Less common forms are small artery atheroma and lipohyalinosis (the lesions described by C. Miller Fisher adjacent to lacunes). Other microvascular lesions that are not reviewed here include cerebral amyloid angiopathy and venous collagenosis. Here, we review the epidemiology, neuropathology, clinical management, genetics, preclinical models, and pathogenesis of hypertensive small vessel disease. Knowledge gaps include initiating factors, molecular pathogenesis, relationships between arterial pathology and tissue damage, possible reversibility, pharmacological targets, and molecular biomarkers. Progress is anticipated from multicell transcriptomic and proteomic profiling, novel experimental models and further target-finding and interventional clinical studies.

Associations of Nativity and the Role of the Hispanic Paradox on the Cognitive Health of Older Latinos Living in the United States

Background

US-based Latinos have lower education and income combined with higher health risks than non-Latino whites, but often 'paradoxically' evidence better health-related outcomes. Less work has investigated this paradox for cognitive-related outcomes despite nativity diversity.

Objective

We evaluated cognitive aging within older Latinos of diverse nativity currently living in the US and participating in Rush Alzheimer's Disease Center studies.

Methods

Participants without baseline dementia, who completed annual neuropsychological assessments (in English or Spanish) were grouped by US-born (n = 117), Mexico-born (n = 173), and born in other Latin American regions (LAr-born = 128). Separate regression models examined associations between nativity and levels of (N = 418) or change in (n = 371; maximum follow-up ∼16 years) global and domain-specific cognition.

Results

Demographically-adjusted linear regression models indicated that foreign-born nativity was associated with lower levels of global cognition and select cognitive domains compared to US-born Latinos. No associations of nativity with cognitive decline emerged from demographically-adjusted mixed-effects models; however, Mexico-born nativity appeared associated with slower declines in working memory compared to other nativity groups (p-values ≥ 0.051). Mexico-born Latinos had relatively higher vascular burden and lower education levels than other nativity groups; however, this did not alter results.

Conclusions

Nativity differences in baseline cognition may be due, in part, to accumulated stressors related to immigration and acculturation experienced by foreign-born Latinos which may hasten meeting criteria for dementia later in life. In contrast, Mexico-born participants' slower working memory declines, taken in the context of other participant characteristics including vascular burden, suggests the Hispanic Paradox may relate to factors with the potential to affect cognition.

Delayed primacy recall performance predicts post mortem Alzheimer's disease pathology from unimpaired ante mortem cognitive baseline

We propose a novel method to assess delayed primacy in the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) memory test. We then examine whether this measure predicts post mortem Alzheimer's disease (AD) neuropathology in individuals who were clinically unimpaired at baseline. A total of 1096 individuals were selected from the Rush Alzheimer's Disease Center database registry. All participants were clinically unimpaired at baseline, and had subsequently undergone brain autopsy. Average age at baseline was 78.8 (6.92). A Bayesian regression analysis was carried out with global pathology as an outcome; demographic, clinical, and apolipoprotein E (APOE) data as covariates; and cognitive predictors, including delayed primacy. Global AD pathology was best predicted by delayed primacy. Secondary analyses showed that delayed primacy was mostly associated with neuritic plaques, whereas total delayed recall was associated with neurofibrillary tangles. Sex differential associations were observed. We conclude that CERAD-derived delayed primacy is a useful metric for early detection and diagnosis of AD in unimpaired individuals.

Highlights

We propose a novel method to analyse serial position in the CERAD memory test.We analyse data from 1096 individuals who were cognitively unimpaired at baseline.Delayed primacy predicts post mortem pathology better than traditional metrics.

Race and sex differences in the longitudinal changes in multidimensional self-reported sleep health characteristics in aging older adults

OBJECTIVES

We examined within-individual changes in self-reported sleep health as community-dwelling older adults age as well as potential differences in these changes by self-reported sex and racial identity.

METHODS

Participants were from the United States and enrolled in the Rush Memory and Aging Project, Minority Aging Research Study, or Religious Orders Study (N = 3539, 20% Black, 75% female, mean 78years [range 65-103]), and they received annual, in-person clinical evaluations (median 5 visits [range 1-27]). A sleep health composite score measured the number of poor sleep characteristics among satisfaction, daytime sleepiness, efficiency, and duration. Mixed effects models estimated associations of age, race, sex, and their interactions on the composite and individual sleep measures, accounting for key confounders.

RESULTS

As they aged, Black participants shifted from reporting two poor sleep characteristics to one poor sleep characteristic, while White participants shifted from one poor characteristic to two. Regardless of age, sex, and race, participants reported that they "often" felt satisfied with their sleep and "sometimes" had trouble staying asleep. Females over age 85 and males of all ages reported the most daytime sleepiness, and older White participants (>age 90) reported the most difficulty falling asleep.

CONCLUSIONS

Although self-reported sleep characteristics were typically stable across age, identifying race and sex differences in self-reported sleep health can help guide future research to understand the mechanisms that underlie these differences.

High-throughput digital quantification of Alzheimer disease pathology and associated infrastructure in large autopsy studies

High-throughput digital pathology offers considerable advantages over traditional semiquantitative and manual methods of counting pathology. We used brain tissue from 5 clinical-pathologic cohort studies of aging; the Religious Orders Study, the Rush Memory and Aging Project, the Minority Aging Research Study, the African American Clinical Core, and the Latino Core to (1) develop a workflow management system for digital pathology processes, (2) optimize digital algorithms to quantify Alzheimer disease (AD) pathology, and (3) harmonize data statistically. Data from digital algorithms for the quantification of β-amyloid (Aβ, n = 413) whole slide images and tau-tangles (n = 639) were highly correlated with manual pathology data (r = 0.83 to 0.94). Measures were robust and reproducible across different magnifications and repeated scans. Digital measures for Aβ and tau-tangles across multiple brain regions reproduced established patterns of correlations, even when samples were stratified by clinical diagnosis. Finally, we harmonized newly generated digital measures with historical measures across multiple large autopsy-based studies. We describe a multidisciplinary approach to develop a digital pathology pipeline that reproducibly identifies AD neuropathologies, Aβ load, and tau-tangles. Digital pathology is a powerful tool that can overcome critical challenges associated with traditional microscopy methods.

High resolution 0.5mm isotropic T1-weighted and diffusion tensor templates of the brain of non-demented older adults in a common space for the MIITRA atlas

High quality, high resolution T1-weighted (T1w) and diffusion tensor imaging (DTI) brain templates located in a common space can enhance the sensitivity and precision of template-based neuroimaging studies. However, such multimodal templates have not been constructed for the older adult brain. The purpose of this work which is part of the MIITRA atlas project was twofold: (A) to develop 0.5 mm isotropic resolution T1w and DTI templates that are representative of the brain of non-demented older adults and are located in the same space, using advanced multimodal template construction techniques and principles of super resolution on data from a large, diverse, community cohort of 400 non-demented older adults, and (B) to systematically compare the new templates to other standardized templates. It was demonstrated that the new MIITRA-0.5mm T1w and DTI templates are well-matched in space, exhibit good definition of brain structures, including fine structures, exhibit higher image sharpness than other standardized templates, and are free of artifacts. The MIITRA-0.5mm T1w and DTI templates allowed higher intra-modality inter-subject spatial normalization precision as well as higher inter-modality intra-subject spatial matching of older adult T1w and DTI data compared to other available templates. Consequently, MIITRA-0.5mm templates allowed detection of smaller inter-group differences for older adult data compared to other templates. The MIITRA-0.5mm templates were also shown to be most representative of the brain of non-demented older adults compared to other templates with submillimeter resolution. The new templates constructed in this work constitute two of the final products of the MIITRA atlas project and are anticipated to have important implications for the sensitivity and precision of studies on older adults.

Differences in Life Space Activity Patterns Between Older Adults With Mild Cognitive Impairment Living Alone or as a Couple: Cohort Study Using Passive Activity Sensing

BACKGROUND

Measuring function with passive in-home sensors has the advantages of real-world, objective, continuous, and unobtrusive measurement. However, previous studies have focused on 1-person homes only, which limits their generalizability.

OBJECTIVE

This study aimed to compare the life space activity patterns of participants living alone with those of participants living as a couple and to compare people with mild cognitive impairment (MCI) with cognitively normal participants in both 1- and 2-person homes.

METHODS

Passive infrared motion sensors and door contact sensors were installed in 1- and 2-person homes with cognitively normal residents or residents with MCI. A home was classified as an MCI home if at least 1 person in the home had MCI. Time out of home (TOOH), independent life space activity (ILSA), and use of the living room, kitchen, bathroom, and bedroom were calculated. Data were analyzed using the following methods: (1) daily averages over 4 weeks, (2) hourly averages (time of day) over 4 weeks, or (3) longitudinal day-to-day changes.

RESULTS

In total, 129 homes with people living alone (n=27, 20.9%, MCI and n=102, 79.1%, no-MCI homes) and 52 homes with people living as a couple (n=24, 46.2%, MCI and n=28, 53.8%, no-MCI homes) were included with a mean follow-up of 719 (SD 308) days. Using all 3 analysis methods, we found that 2-person homes showed a shorter TOOH, a longer ILSA, and shorter living room and kitchen use. In MCI homes, ILSA was higher in 2-person homes but lower in 1-person homes. The effects of MCI status on other outcomes were only found when using the hourly averages or longitudinal day-to-day changes over time, and they depended on the household type (alone vs residing as a couple).

CONCLUSIONS

This study shows that in-home behavior is different when a participant is living alone compared to when they are living as a couple, meaning that the household type should be considered when studying in-home behavior. The effects of MCI status can be detected with in-home sensors, even in 2-person homes, but data should be analyzed on an hour-to-hour basis or longitudinally.

Retrospective Evaluation of Neuropathologic Proxies of the Minimal Atrophy Subtype Compared With Corticolimbic Alzheimer Disease Subtypes

BACKGROUND AND OBJECTIVES

Alzheimer disease (AD) is neuropathologically classified into 3 corticolimbic subtypes based on the neurofibrillary tangle distribution throughout the hippocampus and association cortices: limbic predominant, typical, and hippocampal sparing. In vivo, a fourth subtype, dubbed "minimal atrophy," was identified using structural MRI. The objective of this study was to identify a neuropathologic proxy for the neuroimaging-defined minimal atrophy subtype.

METHODS

We applied 2 strategies in the Florida Autopsied Multi-Ethnic (FLAME) cohort to evaluate a neuropathologic proxy for the minimal atrophy subtype. In the first strategy, we selected AD cases with a Braak tangle stage IV (Braak IV) because of the relative paucity of neocortical tangle involvement compared with Braak >IV. Braak IV cases were compared with the 3 AD subtypes. In the alternative strategy, typical AD was stratified by brain weight and cases having a relatively high brain weight (>75th percentile) were defined as minimal atrophy.

RESULTS

Braak IV cases (n = 37) differed from AD subtypes (limbic predominant [n = 174], typical [n = 986], and hippocampal sparing [n = 187] AD) in having the least years of education (median 12 years, group-wise p < 0.001) and the highest brain weight (median 1,140 g, p = 0.002). Braak IV cases most resembled the limbic predominant cases owing to their high proportion of APOE ε4 carriers (75%, p < 0.001), an amnestic syndrome (100%, p < 0.001), as well as older age of cognitive symptom onset and death (median 79 and 85 years, respectively, p < 0.001). Only 5% of Braak IV cases had amygdala-predominant Lewy bodies (the lowest frequency observed, p = 0.017), whereas 32% had coexisting pathology of Lewy body disease, which was greater than the other subtypes (p = 0.005). Nearly half (47%) of the Braak IV samples had coexisting limbic predominant age-related TAR DNA-binding protein 43 encephalopathy neuropathologic change. Cases with a high brain weight (n = 201) were less likely to have amygdala-predominant Lewy bodies (14%, p = 0.006) and most likely to have Lewy body disease (31%, p = 0.042) compared with those with middle (n = 455) and low (n = 203) brain weight.

DISCUSSION

The frequency of Lewy body disease was increased in both neuropathologic proxies of the minimal atrophy subtype. We hypothesize that Lewy body disease may underlie cognitive decline observed in minimal atrophy cases.

Neuropathologic correlates of cerebral microbleeds in community-based older adults

Cerebral microbleeds (CMBs) appearing as hypointense foci on T2*-weighted magnetic resonance images are small hemorrhages that have been linked to cognitive decline and increased mortality. However, the neuropathologic correlates of CMBs in community-based older adults are poorly understood. The present study investigated the association of age-related neuropathologies with CMBs in community-based older adults. Cerebral hemispheres from 289 participants of the Rush Memory and Aging Project, Religious Orders Study, Minority Aging Research Study, and Rush Alzheimer's Disease Clinical Core underwent ex vivo MRI and detailed neuropathologic examination. Following Bonferroni correction, CMBs in the cerebrum overall and in the frontal lobe were associated with cerebral amyloid angiopathy, CMBs in the frontal lobe were also associated with arteriolosclerosis, and CMBs in the basal ganglia showed a borderline significant association with microinfarcts. These findings suggest that CMBs can aid in the prediction of small vessel disease in community-based older adults. Finally, CMBs were not associated with dementia, suggesting that CMBs in community-based older adults may not be linked to substantial cognitive impairment.

Associations of Sex, Race, and Apolipoprotein E Alleles With Multiple Domains of Cognition Among Older Adults

Importance

Sex differences are established in associations between apolipoprotein E (APOE) ε4 and cognitive impairment in Alzheimer disease (AD). However, it is unclear whether sex-specific cognitive consequences of APOE are consistent across races and extend to the APOE ε2 allele.

Objective

To investigate whether sex and race modify APOE ε4 and ε2 associations with cognition.

Design, Setting, and Participants

This genetic association study included longitudinal cognitive data from 4 AD and cognitive aging cohorts. Participants were older than 60 years and self-identified as non-Hispanic White or non-Hispanic Black (hereafter, White and Black). Data were previously collected across multiple US locations from 1994 to 2018. Secondary analyses began December 2021 and ended September 2022.

Main Outcomes and Measures

Harmonized composite scores for memory, executive function, and language were generated using psychometric approaches. Linear regression assessed interactions between APOE ε4 or APOE ε2 and sex on baseline cognitive scores, while linear mixed-effect models assessed interactions on cognitive trajectories. The intersectional effect of race was modeled using an APOE × sex × race interaction term, assessing whether APOE × sex interactions differed by race. Models were adjusted for age at baseline and corrected for multiple comparisons.

Results

Of 32 427 participants who met inclusion criteria, there were 19 007 females (59%), 4453 Black individuals (14%), and 27 974 White individuals (86%); the mean (SD) age at baseline was 74 years (7.9). At baseline, 6048 individuals (19%) had AD, 4398 (14%) were APOE ε2 carriers, and 12 538 (38%) were APOE ε4 carriers. Participants missing APOE status were excluded (n = 9266). For APOE ε4, a robust sex interaction was observed on baseline memory (β = -0.071, SE = 0.014; P = 9.6 × 10-7), whereby the APOE ε4 negative effect was stronger in females compared with males and did not significantly differ among races. Contrastingly, despite the large sample size, no APOE ε2 × sex interactions on cognition were observed among all participants. When testing for intersectional effects of sex, APOE ε2, and race, an interaction was revealed on baseline executive function among individuals who were cognitively unimpaired (β = -0.165, SE = 0.066; P = .01), whereby the APOE ε2 protective effect was female-specific among White individuals but male-specific among Black individuals.

Conclusions and Relevance

In this study, while race did not modify sex differences in APOE ε4, the APOE ε2 protective effect could vary by race and sex. Although female sex enhanced ε4-associated risk, there was no comparable sex difference in ε2, suggesting biological pathways underlying ε4-associated risk are distinct from ε2 and likely intersect with age-related changes in sex biology.

Explainable deep learning approach for extracting cognitive features from hand-drawn images of intersecting pentagons

Hand drawing, which requires multiple neural systems for planning and controlling sequential movements, is a useful cognitive test for older adults. However, the conventional visual assessment of these drawings only captures limited attributes and overlooks subtle details that could help track cognitive states. Here, we utilized a deep-learning model, PentaMind, to examine cognition-related features from hand-drawn images of intersecting pentagons. PentaMind, trained on 13,777 images from 3111 participants in three aging cohorts, explained 23.3% of the variance in the global cognitive scores, 1.92 times more than the conventional rating. This accuracy improvement was due to capturing additional drawing features associated with motor impairments and cerebrovascular pathologies. By systematically modifying the input images, we discovered several important drawing attributes for cognition, including line waviness. Our results demonstrate that deep learning models can extract novel drawing metrics to improve the assessment and monitoring of cognitive decline and dementia in older adults.

Effects of Cerebrovascular and Lewy Body Pathology on Parkinsonian Signs in Community-Dwelling Older Adults

BACKGROUND AND OBJECTIVES

The roles of Lewy body (LB) and separately of cerebrovascular disease (CVD) pathologies in the severity of parkinsonian signs are well recognized in old age. We investigated whether the 2 pathologies act synergistically to further potentiate the severity of parkinsonism beyond their separate effects.

METHODS

We used postmortem data of decedents from 3 longitudinal community-based studies of aging who underwent annual clinical evaluation to assess parkinsonian signs using 26 items of the motor portion of a modified Unified Parkinson Disease Rating Scale. A summary score was developed from each item score to construct a global parkinsonian score, with a higher score indicating more severe parkinsonism. A detailed neuropathologic evaluation was performed to identify LB, Alzheimer disease pathology, nigral neuronal loss, atherosclerosis, macroscopic infarcts, and other CVD pathologies (arteriolosclerosis, cerebral amyloid angiopathy, and microscopic infarcts). A series of regression models with terms for LB, CVD pathology, and the interaction of LB with CVD pathologies was fit for global parkinsonism proximate to death and for individual parkinsonian signs scores including, parkinsonian gait, rigidity, tremor, and bradykinesia.

RESULTS

In 1,753 participants (mean age at death = 89 years; 68% women), LB was observed in 26% of participants, and CVD pathologies were present in more than two-thirds of participants. LB and 3 CVD pathologies (atherosclerosis, arteriolosclerosis, and macroscopic infarcts) were each independently associated with the severity of global parkinsonism proximate to death (LB: β = 0.318, SE = 0.08, p < 0.001; atherosclerosis: β = 0.373, SE = 0.079, p < 0.001; arteriolosclerosis: β = 0.253, SE = 0.078, p = 0.001; macroscopic infarcts: β = 0.333, SE = 0.077, p < 0.001). A linear regression model adjusted for demographics, CVD, and neurodegenerative pathologies showed interaction between LB and macroscopic infarcts (β = 0.463, SE = 0.168, p = 0.006), with LBs being associated with worse global parkinsonism when macroinfarcts are present. Similar interactions were found for atherosclerosis and LBs (β = 0.371, SE = 0.173, p = 0.032) and for parkinsonian gait as the outcome (macroscopic infarcts: β = 0.662, SE = 0.239, p = 0.005; atherosclerosis: β = 0.509, SE = 0.246, p = 0.038). Findings were not affected when the 66 participants with a clinical diagnosis of Parkinson disease were excluded. By contrast, there were no interactions between LB and other CVD pathologies or between atherosclerosis and macroscopic infarcts for global parkinsonism proximate to death.

DISCUSSION

These findings suggest that atherosclerosis and macroscopic infarcts interact with LB pathology to increase the severity of parkinsonism beyond their additive effects in older persons.

Quantification of race/ethnicity representation in Alzheimer's disease neuroimaging research in the USA: a systematic review

BACKGROUND

Racial and ethnic minoritized groups are disproportionately at risk for Alzheimer's Disease (AD), but are not sufficiently recruited in AD neuroimaging research in the United States. This is important as sample composition impacts generalizability of findings, biomarker cutoffs, and treatment effects. No studies have quantified the breadth of race/ethnicity representation in the AD literature.

METHODS

This review identified median race/ethnicity composition of AD neuroimaging US-based research samples available as free full-text articles on PubMed. Two types of published studies were analyzed: studies that directly report race/ethnicity data (i.e., direct studies), and studies that do not report race/ethnicity but used data from a cohort study/database that does report this information (i.e., indirect studies).

RESULTS

Direct studies (n = 719) have median representation of 88.9% white or 87.4% Non-Hispanic white, 7.3% Black/African American, and 3.4% Hispanic/Latino ethnicity, with 0% Asian American, Native Hawaiian/Pacific Islander, and American Indian/Alaska Native, Multiracial, and Other Race participants. Cohort studies/databases (n = 44) from which indirect studies (n = 1745) derived are more diverse, with median representation of 84.2% white, 83.7% Non-Hispanic white, 11.6% Black/African American, 4.7% Hispanic/Latino, and 1.75% Asian American participants. Notably, 94% of indirect studies derive from just 10 cohort studies/databases. Comparisons of two time periods using a median split for publication year, 1994-2017 and 2018-2022, indicate that sample diversity has improved recently, particularly for Black/African American participants (3.39% from 1994-2017 and 8.29% from 2018-2022).

CONCLUSIONS

There is still underrepresentation of all minoritized groups relative to Census data, especially for Hispanic/Latino and Asian American individuals. The AD neuroimaging literature will benefit from increased representative recruitment of ethnic/racial minorities. More transparent reporting of race/ethnicity data is needed.

Delayed primacy recall performance predicts post mortem Alzheimer's disease pathology from unimpaired ante mortem cognitive baseline

INTRODUCTION

We propose a novel method to assess delayed primacy in the CERAD memory test. We then examine whether this measure predicts post mortem Alzheimer's disease (AD) neuropathology in individuals who were clinically unimpaired at baseline.

METHODS

A total of 1096 individuals were selected from the Rush Alzheimer's Disease Center database registry. All participants were clinically unimpaired at baseline, and had subsequently undergone brain autopsy. Average age at baseline was 78.8 (6.92). A Bayesian regression analysis was carried out with global pathology as outcome; demographic, clinical and APOE data as covariates; and cognitive predictors, including delayed primacy.

RESULTS

Global AD pathology was best predicted by delayed primacy. Secondary analyses showed that delayed primacy was mostly associated with neuritic plaques, whereas total delayed recall was associated with neurofibrillary tangles.

DISCUSSION

We conclude that CERAD-derived delayed primacy is a useful metric for early detection and diagnosis of AD in unimpaired individuals.

Admixture mapping identifies novel Alzheimer's disease risk regions in African Americans

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.

Brain vitamin D forms, cognitive decline, and neuropathology in community-dwelling older adults

INTRODUCTION

Vitamin D purportedly protects against cognitive decline and dementia based on observational data using circulating 25-hydroxyvitamin D (25(OH)D). Little is known about vitamin D in the human brain and the association with dementia or neuropathology.

METHODS

Decedents of the Rush Memory and Aging Project (n = 290) had vitamin D concentrations measured in four brain regions. Associations with cognitive and neuropathological outcomes were estimated using linear and logistic regression.

RESULTS

The main form of vitamin D in all brain regions measured was 25(OH)D3 . Higher brain 25(OH)D3 concentrations were associated with a 25% to 33% lower odds of dementia or mild cognitive impairment (MCI) at the last visit before death (all P ≤ .031). However, brain 25(OH)D concentrations were not associated with any post-mortem neuropathology outcome studied.

DISCUSSION

Higher brain 25(OH)D3 concentrations were associated with better cognitive function prior to death. Additional research is needed to clarify the specific mechanisms underlying this potentially protective relationship.

Associations Between Loneliness and Cognitive Resilience to Neuropathology in Older Adults

OBJECTIVES

Loneliness in the aging population is associated with decreased cognitive function and increased neuropathology; less is understood about the association of loneliness and cognitive resilience (CR), defined as the discordance between a person's actual and expected cognition given their neuropathology. Here we assess the effect of loneliness and change in loneliness on CR at end of life and across older adulthood.

METHODS

Data were combined from 2 longitudinal studies of older adults. CR proximate to death (CRlast_level) and across time (CRslope) was obtained by independently regressing global cognition and change in cognition onto multiple neuropathology indicators and extracting the resulting residuals. We used a series of simple linear regression models to assess the effect of loneliness level and change on CRlast_level and CRslope.

RESULTS

Higher baseline loneliness was associated with lower CRlast_level (β = -0.11, 95% confidence interval [95% CI; -0.18, -0.04], p < .01); higher baseline loneliness and increasing loneliness over time was associated with lower CRslope (β = -0.13, 95% CI [-0.22, -0.05], p < .01 and β = -0.12, 95% CI [-0.20, -0.04], p < .01, respectively). Results were robust to covariate inclusion and independent of objective social isolation.

DISCUSSION

Higher and increasing loneliness was associated with lower CR in the face of neuropathology. These results suggest that some individuals are less resilient to the accumulation of neuropathology than others, and experiencing high/increasing loneliness is a key factor putting some at risk. Interventions aimed at optimizing cognitive function across older adults should include loneliness reduction as a potential area of focus.

Associations between circulating cell-free mitochondrial DNA, inflammatory markers, and cognitive and physical outcomes in community dwelling older adults

BACKGROUND

Dementia and frailty are common age-related syndromes often linked to chronic inflammation. Identifying the biological factors and pathways that contribute to chronic inflammation is crucial for developing new therapeutic targets. Circulating cell-free mitochondrial DNA (ccf-mtDNA) has been proposed as an immune stimulator and potential predictor of mortality in acute illnesses. Dementia and frailty are both associated with mitochondrial dysfunction, impaired cellular energetics, and cell death. The size and abundance of ccf-mtDNA fragments may indicate the mechanism of cell death: long fragments typically result from necrosis, while short fragments arise from apoptosis. We hypothesize that increased levels of necrosis-associated long ccf-mtDNA fragments and inflammatory markers in serum are linked to declines in cognitive and physical function, as well as increased mortality risk.

RESULTS

Our study of 672 community-dwelling older adults revealed that inflammatory markers (C-Reactive Protein, soluble tumor necrosis factor alpha, tumor necrosis factor alpha receptor 1 [sTNFR1], and interleukin-6 [IL-6]) positively correlated with ccf-mtDNA levels in serum. Although cross-sectional analysis revealed no significant associations between short and long ccf-mtDNA fragments, longitudinal analysis demonstrated a connection between higher long ccf-mtDNA fragments (necrosis-associated) and worsening composite gait scores over time. Additionally, increased mortality risk was observed only in individuals with elevated sTNFR1 levels.

CONCLUSION

In a community dwelling cohort of older adults, there are cross-sectional and longitudinal associations between ccf-mtDNA and sTNFR1 with impaired physical and cognitive function and increased hazard of death. This work suggests a role for long ccf-mtDNA as a blood-based marker predictive of future physical decline.

Neighborhood-level social vulnerability and individual-level cognitive and motor functioning over time in older non-Latino Black and Latino adults

Introduction

Despite known health disparities in cognitive aging, a comprehensive rationale for the increased burden in older minoritized populations including non-Latino Black and Latino adults has yet to be elucidated. While most work has focused on person-specific risk, studies are increasingly assessing neighborhood-level risk. We evaluated multiple aspects of the environmental milieu that may be critical when considering vulnerability to adverse health outcomes.

Methods

We investigated associations between a Census-tract derived Social Vulnerability Index (SVI) and level of and change in cognitive and motor functioning in 780 older adults (590 non-Latino Black adults, ∼73 years old at baseline; 190 Latinos, ∼70 years old baseline). Total SVI scores (higher = greater neighborhood-level vulnerability) were combined with annual evaluations of cognitive and motor functioning (follow-up ranged from 2 to 18 years). Demographically-adjusted mixed linear regression models tested for associations between SVI and cognitive and motor outcomes in analyses stratified by ethno-racial group.

Results

For non-Latino Black participants, higher SVI scores were associated with lower levels of global cognitive and motor functioning-specifically, episodic memory, motor dexterity and gait-as well as longitudinal change in visuospatial abilities and hand strength. For Latinos, higher SVI scores were associated with lower levels of global motor functioning only-specifically, motor dexterity; there were no significant associations between SVI and change in motor functioning.

Discussion

Neighborhood-level social vulnerability is associated with cognitive and motor functioning in non-Latino Black and Latino older adults, although associations appear to contribute to level more so than longitudinal change.

Late-life depressive symptoms and white matter structural integrity within older Black adults

Introduction

Older Black adults experience a high burden of depressive symptoms and cerebrovascular disease but the specific neurobiological substrates underlying the association between late-life depressive symptoms and brain integrity are understudied, particularly in within-group designs.

Methods

Using the Center for Epidemiologic Studies Depression Scale and diffusion-tensor imaging, within-Black variation in the association between late-life depressive symptoms and white matter structural integrity was examined in 297 older Black participants without dementia that were enrolled across three epidemiological studies of aging and dementia. Linear regression models were used to test associations with DTI metrics (fractional anisotropy, trace of the diffusion tensor) as the outcomes and depressive symptoms as the predictor, while adjusting for age, sex, education, scanner, serotonin-reuptake inhibitor use, total volume of white-matter hyperintensities normalized by intracranial volume, and presence of white-matter hyperintensities at the voxel level.

Results

Higher level of self-reported late-life depressive symptoms was associated with greater diffusion-tensor trace (reduced white matter integrity) in connections between commissural pathways and contralateral prefrontal regions (superior and middle frontal/dorsolateral prefrontal cortex), association pathways connecting dorsolateral prefrontal cortex with insular, striatal and thalamic regions, and association pathways connecting the parietal, temporal and occipital lobes and the thalamus.

Discussion

This study demonstrated a discernable pattern of compromised white matter structural integrity underlying late-life depressive symptoms within older Black adults.

Cognitive domain harmonization and cocalibration in studies of older adults

OBJECTIVE

Studies use different instruments to measure cognitirating cognitive tests permit direct comparisons of individuals across studies and pooling data for joint analyses.

METHOD

We began our legacy item bank with data from the Adult Changes in Thought study (n = 5,546), the Alzheimer's Disease Neuroimaging Initiative (n = 3,016), the Rush Memory and Aging Project (n = 2,163), and the Religious on such as the Mini-Mental State Examination, the Alzheimer's Disease Assessment Scale-Cognitive Subscale, the Wechsler Memory Scale, and the Boston Naming Test. CocalibOrders Study (n = 1,456). Our workflow begins with categorizing items administered in each study as indicators of memory, executive functioning, language, visuospatial functioning, or none of these domains. We use confirmatory factor analysis models with data from the most recent visit on the pooled sample across these four studies for cocalibration and derive item parameters for all items. Using these item parameters, we then estimate factor scores along with corresponding standard errors for each domain for each study. We added additional studies to our pipeline as available and focused on thorough consideration of candidate anchor items with identical content and administration methods across studies.

RESULTS

Prestatistical harmonization steps such qualitative and quantitative assessment of granular cognitive items and evaluating factor structure are important steps when trying to cocalibrate cognitive scores across studies. We have cocalibrated cognitive data and derived scores for four domains for 76,723 individuals across 10 studies.

CONCLUSIONS

We have implemented a large-scale effort to harmonize and cocalibrate cognitive domain scores across multiple studies of cognitive aging. Scores on the same metric facilitate meta-analyses of cognitive outcomes across studies or the joint analysis of individual data across studies. Our systematic approach allows for cocalibration of additional studies as they become available and our growing item bank enables robust investigation of cognition in the context of aging and dementia. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Interpretable deep learning approach for extracting cognitive features from hand-drawn images of intersecting pentagons in older adults

Hand drawing involves multiple neural systems for planning and precise control of sequential movements, making it a valuable cognitive test for older adults. However, conventional visual assessment of drawings may not capture intricate nuances that could help track cognitive states. To address this issue, we utilized a deep-learning model, PentaMind, to examine cognition-related features from hand-drawn images of intersecting pentagons. PentaMind, trained on 13,777 images from 3,111 participants in three aging cohorts, explained 23.3% of the variance in global cognitive scores, a comprehensive hour-long cognitive battery. The model’s performance, which was 1.92 times more accurate than conventional visual assessment, significantly improved the detection of cognitive decline. The improvement in accuracy was due to capturing additional drawing features that we found to be associated with motor impairments and cerebrovascular pathologies. By systematically modifying the input images, we discovered several important drawing attributes for cognition, including line waviness. Our results demonstrate that hand-drawn images can provide rich cognitive information, enabling rapid assessment of cognitive decline and suggesting potential clinical implications in dementia.

Improving generalizability and study design of Alzheimer's disease cohort studies in the United States by including under-represented populations

The poor generalizability of clinical research data due to the enrollment of highly educated, non-Latinx White participants hampers the development of therapies for Alzheimer's disease (AD). Black and Latinx older adults have a greater risk for dementia, yet it is unclear how health-care disparities and sociocultural factors influence potential AD therapies and prognosis. Low enrollment of under-represented populations may be attributable to several factors including greater exclusion due to higher rates of comorbidities, lower access to AD clinics, and the legacy of unethical treatment in medical research. This perspective outlines solutions tested in the Brain Health Registry (BHR) and the Alzheimer's Disease Neuroimaging Initiative (ADNI), including culturally-informed digital research methods, community-engaged research strategies, leadership from under-represented communities, and the reduction of exclusion criteria based on comorbidities. Our successes demonstrate that it is possible to increase the inclusion and engagement of under-represented populations into US-based clinical studies, thereby increasing the generalizability of their results.

Subjective Cognitive Decline Is Associated With Lower Baseline Cognition and Increased Rate of Cognitive Decline

OBJECTIVES

Subjective cognitive decline (SCD) is a known risk factor for Alzheimer's disease. However, little research has examined whether healthy older adults with SCD (SCD+) exhibit lower cognition and increased rates of cognitive decline compared to those without SCD (SCD-). The goal of this study was to examine if cognitive change over a 15-year period differs between SCD+ and SCD-.

METHOD

3,019 cognitively normal older adults (831 SCD+) from 3 Rush Alzheimer's Disease Center cohort studies were followed annually for up to a maximum of 15 years. Due to attrition, the average follow-up time was 5.7 years. Cognition was measured using z-scores of global cognition, episodic memory, semantic memory, perceptual speed, visuospatial ability, and working memory. Linear mixed-effects models investigated whether SCD was associated with cognitive change.

RESULTS

Both baseline cognition and cognitive change over time differed between SCD+ and SCD-. People with SCD+ exhibited lower baseline scores and a steeper decline in global cognition, episodic memory, semantic memory, and perceptual speed. People with SCD+ did not differ from SCD- in baseline visuospatial ability or working memory but exhibited increased change over time in those two domains compared to SCD-.

DISCUSSION

The observed results reveal that older adults with SCD+ have lower baseline cognition and steeper declines in cognition over time compared to SCD-. Older adults with SCD may be aware of subtle cognitive declines that occur over time in global cognition, episodic memory, semantic memory, perceptual speed, visuospatial ability, and working memory compared to those without SCD.

Rationale for the selection of dual primary endpoints in prevention studies of cognitively unimpaired individuals at genetic risk for developing symptoms of Alzheimer's disease

BACKGROUND

There is a critical need for novel primary endpoints designed to detect early and subtle changes in cognition in clinical trials targeting the asymptomatic (preclinical) phase of Alzheimer's disease (AD). The Alzheimer's Prevention Initiative (API) Generation Program, conducted in cognitively unimpaired individuals at risk of developing AD (e.g., enriched by the apolipoprotein E (APOE) genotype), used a novel dual primary endpoints approach, whereby demonstration of treatment effect in one of the two endpoints is sufficient for trial success. The two primary endpoints were (1) time to event (TTE)-with an event defined as a diagnosis of mild cognitive impairment (MCI) due to AD and/or dementia due to AD-and (2) change from baseline to month 60 in the API Preclinical Composite Cognitive (APCC) test score.

METHODS

Historical observational data from three sources were used to fit models to describe the TTE and the longitudinal APCC decline, both in people who do and do not progress to MCI or dementia due to AD. Clinical endpoints were simulated based on the TTE and APCC models to assess the performance of the dual endpoints versus each of the two single endpoints, with the selected treatment effect ranging from a hazard ratio (HR) of 0.60 (40% risk reduction) to 1 (no effect).

RESULTS

A Weibull model was selected for TTE, and power and linear models were selected to describe the APCC score for progressors and non-progressors, respectively. Derived effect sizes in terms of reduction of the APCC change from baseline to year 5 were low (0.186 for HR = 0.67). The power for the APCC alone was consistently lower compared to the power of TTE alone (58% [APCC] vs 84% [TTE] for HR = 0.67). Also, the overall power was higher for the 80%/20% distribution (82%) of the family-wise type 1 error rate (alpha) between TTE and APCC compared to 20%/80% (74%).

CONCLUSIONS

Dual endpoints including TTE and a measure of cognitive decline perform better than the cognitive decline measure as a single primary endpoint in a cognitively unimpaired population at risk of AD (based on the APOE genotype). Clinical trials in this population, however, need to be large, include older age, and have a long follow-up period of at least 5 years to be able to detect treatment effects.

Perceptions of Caring Recruitment Among Older Adults: African Americans and Non-Latinx Whites

BACKGROUND

African Americans (AAs) are underrepresented in health-related research studies. Few studies have investigated how behaviors of study recruiters affect recruitment of older AAs versus non-Latinx Whites (NLWs).

OBJECTIVES

The aim of this study was to explore whether caring behaviors influence AA and NLW older adults' decision to participate in hypothetical, high-commitment, health-related research studies and differences in participants' enrollment decisions by race.

METHODS

Using a descriptive, cross-sectional study design, guided by Kristen Swanson's middle-range theory of caring, a research-savvy sample of 60 AA and 60 NLW adults (age > 65 years) were randomly assigned one of two written vignettes. The concept of caring behaviors was manipulated and illustrated in a hypothetical recruitment scenario. A participant feedback survey was used to assess (a) participants' perceptions of caring and uncaring behaviors exhibited by the fictitious research recruiter, (b) differences in their willingness to participate based on vignette type, and (c) participants' judgment of the research recruiter as being caring or uncaring. A chi-square test assessed the association among categorical variables (caring behavior and participants' race).

RESULTS

Participants who received the vignette with the high caring recruiter were more than twice as likely to agree to participate in the study than those who received the vignette with the low caring recruiter. AA and NLW participants did not differ in their likelihood to agree to participate. Participants who received the caring vignette and judged the recruiter as caring were 5 times as likely to agree to participate in the high-commitment study than those who received the uncaring vignette ( p < .001). Associations did not vary by race.

DISCUSSION

This experimental study of equally recruited older adults from an existing longitudinal study revealed that caring behaviors in recruitment strategies are associated with an increased likelihood of participation in high-commitment research with older adults. The research-savvy AA participants were just as likely to participate in the hypothetical high-commitment research as their NLW peers when the fictional research recruiter was perceived as having caring behaviors. When targeting specific populations, it is essential to employ nuanced recruitment approaches where the study recruiters are attuned to caring behaviors.

Decision Making and Blood Sugar Indicators in Older African American Adults

Objectives: Decision making is a modifiable behavior associated with health outcomes. We investigated the association of decision making with blood sugar indicators in older community-dwelling African American adults. Methods: Participants were 328 older African American adults from community-based studies (mean age = 78). Decision making was assessed using a performance-based measure (range: 0-12). Blood sugar indicators were non-fasting hemoglobin A1c and blood glucose. Using regression, we assessed the relationship between decision making and each blood sugar indicator, controlling for demographics. We additionally examined if an association varied by known diabetes diagnosis. Results: Lower decision making was associated with higher HbA1c (b: -0.05, p-value: .03), but not blood glucose. In an interaction analysis, the association of lower decision making with higher levels of HbA1c was present only among individuals with known diabetes (b (with diabetes): -0.13, p-value: <.01). Discussion: Decision making may contribute to glycemic control in African American older adults with diabetes.

A Qualitative Examination of Knowledge, Experiences, and Considerations of PET Brain Scan Participation Among Older Black and Latino Adults

BACKGROUND

Biological biomarkers yielded from positron emission tomography (PET) brain scans serve as a pathway to understanding Alzheimer's disease pathology. PET brain scan data remain limited for populations traditionally under-included in aging research.

OBJECTIVE

The purpose of this qualitative study was to examine participant-identified barriers to PET brain scan consent and characterize participant-informed elements of educational materials needed to facilitate PET brain scan participation among older Black and Latino adults.

METHODS

Participants (N = 31) were older adults (mean age = 71 years) who self-identified as either non-Latino Black (n = 15) or Latino (n = 16). Each participant took part in a one-time, in-depth individual interview. Researchers analyzed data guided by a Grounded Theory Approach with both Open Coding and Constant Comparative Coding.

RESULTS

Four overarching themes emerged across all participants: 1) knowledge limitations; 2) requirements for consent; 3) motivators for participation; and 4) social networks. Within the four themes, there were differences based on participant ethnoracial group. For example, for Theme Three, older Black adults indicated that they would expect compensation for PET brain scan participation. Conversely, older Latinos stated that they would appreciate, but not anticipate, a financial incentive. All participants stressed the importance of written educational materials with subsequent verbal discussions with studystaff.

CONCLUSION

Findings inform the development and implementation of scientifically-relevant and culturally-cognizant engagement approaches, educational materials, and recruitment strategies to increase PET brain scan participation by diverse older adults.