Association between enrollment factors and incident cognitive impairment in Blacks and Whites: Data from the Alzheimer's Disease Center

A systematic review/meta-analysis of prevalence and incidence rates illustrates systemic underrepresentation of individuals racialized as Asian and/or Asian-American in ADRD research

We investigate Alzheimer's disease and related dementia (ADRD) prevalence, incidence rate, and risk factors in individuals racialized as Asian and/or Asian-American and assess sample representation. Prevalence, incidence rate, risk factors, and heterogeneity of samples were assessed. Random-effects meta-analysis was conducted, generating pooled estimates. Of 920 records across 14 databases, 45 studies were included. Individuals racialized as Asian and/or Asian-American were mainly from Eastern and Southern Asia, had higher education, and constituted a smaller sample relative to non-Hispanic white cohorts. The average prevalence was 10.9%, ranging from 0.4% to 46%. The average incidence rate was 20.03 (12.01-33.8) per 1000 person-years with a range of 75.19-13.59 (12.89-14.33). Risk factors included physiological, genetic, psychological, behavioral, and social factors. This review underscores the systemic underrepresentation of individuals racialized as Asian and/or Asian-American in ADRD research and the need for inclusive approaches accounting for culture, language, and immigration status. HIGHLIGHTS: There is considerable heterogeneity in the prevalence of ADRD among studies of Asian-Americans. There is limited data on group-specific risk factors for ADRD among Asian-Americans. The average prevalence of (ADRD) among Asian-Americans was found to be 7.4%, with a wide range from 0.5% to 46%.

Data-driven classification of cognitively normal and mild cognitive impairment subtypes predicts progression in the NACC dataset

INTRODUCTION

Data-driven neuropsychological methods can identify mild cognitive impairment (MCI) subtypes with stronger associations to dementia risk factors than conventional diagnostic methods.

METHODS

Cluster analysis used neuropsychological data from participants without dementia (mean age = 71.6 years) in the National Alzheimer's Coordinating Center (NACC) Uniform Data Set (n = 26,255) and the "normal cognition" subsample (n = 16,005). Survival analyses examined MCI or dementia progression.

RESULTS

Five clusters were identified: "Optimal" cognitively normal (oCN; 13.2%), "Typical" CN (tCN; 28.0%), Amnestic MCI (aMCI; 25.3%), Mixed MCI-Mild (mMCI-Mild; 20.4%), and Mixed MCI-Severe (mMCI-Severe; 13.0%). Progression to dementia differed across clusters (oCN < tCN < aMCI < mMCI-Mild < mMCI-Severe). Cluster analysis identified more MCI cases than consensus diagnosis. In the "normal cognition" subsample, five clusters emerged: High-All Domains (High-All; 16.7%), Low-Attention/Working Memory (Low-WM; 22.1%), Low-Memory (36.3%), Amnestic MCI (16.7%), and Non-amnestic MCI (naMCI; 8.3%), with differing progression rates (High-All < Low-WM = Low-Memory < aMCI < naMCI).

DISCUSSION

Our data-driven methods outperformed consensus diagnosis by providing more precise information about progression risk and revealing heterogeneity in cognition and progression risk within the NACC "normal cognition" group.

Plasma biomarkers for Alzheimer's and related dementias: A review and outlook for clinical neuropsychology

Recent technological advances have improved the sensitivity and specificity of blood-based biomarkers for Alzheimer's disease and related dementias. Accurate quantification of amyloid-ß peptide, phosphorylated tau (pTau) isoforms, as well as markers of neurodegeneration (neurofilament light chain [NfL]) and neuro-immune activation (glial fibrillary acidic protein [GFAP] and chitinase-3-like protein 1 [YKL-40]) in blood has allowed researchers to characterize neurobiological processes at scale in a cost-effective and minimally invasive manner. Although currently used primarily for research purposes, these blood-based biomarkers have the potential to be highly impactful in the clinical setting - aiding in diagnosis, predicting disease risk, and monitoring disease progression. Whereas plasma NfL has shown promise as a non-specific marker of neuronal injury, plasma pTau181, pTau217, pTau231, and GFAP have demonstrated desirable levels of sensitivity and specificity for identification of individuals with Alzheimer's disease pathology and Alzheimer's dementia. In this forward looking review, we (i) provide an overview of the most commonly used blood-based biomarkers for Alzheimer's disease and related dementias, (ii) discuss how comorbid medical conditions, demographic, and genetic factors can inform the interpretation of these biomarkers, (iii) describe ongoing efforts to move blood-based biomarkers into the clinic, and (iv) highlight the central role that clinical neuropsychologists may play in contextualizing and communicating blood-based biomarker results for patients.

COVID-19 pandemic's relationship with enrollment at US Alzheimer's Disease Research Centers

INTRODUCTION

We aimed to characterize the COVID-19 pandemic's relationship with enrollment in US Alzheimer's Disease Research Centers (ADRCs).

METHODS

Using data on 10,105 participants from 30 ADRCs, we conducted interrupted time series analyses to assess the relationship of the pandemic with enrollment and calculate projected dates of enrollment recovery.

RESULTS

Participants enrolled during the pandemic (vs pre-pandemic) were more likely to have dementia and be referred by health professionals. The pandemic was associated with a 77% drop in enrollment, with projected trend recovery in March 2024 and 100% recovery in September 2024. COVID was associated with a 91% drop in Black/African American participants, compared to 71% in White participants. Enrollment of both Hispanic and female participants was declining 1.4% and 0.3%/month pre-pandemic.

DISCUSSION

Funders and researchers should account for ongoing COVID-19 impact on ADRD research enrollment. Strategies to speed enrollment recovery are needed, especially for Black/African American and Hispanic groups.

HIGHLIGHTS

Tested COVID pandemic association with enrollment at Alzheimer's Disease Research Centers. During versus pre-pandemic enrollees differed on demographic and clinical variables. Interrupted time series analyses: immediate 77% drop in enrollment related to COVID. Recovery projections: trend recovery in March 2024, 100% recovery in September 2024. Enrollment of African American and Hispanic participants should be prioritized.

Informant sex/gender moderates associations between reported functioning and memory performance in Mexican American adults

Objective: In neuropsychological evaluations, assessing cognitive functioning is often achieved using objective neuropsychological measures, whereas subjective informant reports are typically obtained to determine manifest daily functioning. Informant reports of participant functioning and their associations with objective participant performance on neuropsychological testing have been shown to vary based on informant characteristics. However, associations among informant characteristics, reported functioning, and neuropsychological performance have not been adequately examined with Mexican American or other Hispanic/Latino samples, despite these populations' disproportionately higher rates of dementia due to Alzheimer's disease and related disorders. Method: We examined associations of informant characteristics with informant reports of participant functioning (assessed via the Functional Activities Questionnaire [FAQ]), and potential moderating effects of these characteristics on associations between reported functioning and participant performance on neuropsychological testing, for Mexican American adult participants in the National Alzheimer's Coordinating Center cohort (n = 294). Results: Female informants reported significantly worse participant functioning compared to male informants (p = .035, r = .126). Moreover, significant associations between reported functioning and memory performance were observed for participants with female informants, but not for those with male informants (p = .024, r = .138). Higher levels of informant education were associated with significantly worse participant functioning (p = .011, r = .151). However, informant education did not moderate associations between reported functioning and neuropsychological performance (ps > .05). Conclusions: Compared to male informants, female informants may provide subjective reports of Mexican American participant functioning that more closely corroborate objective participant performance in memory.

Reliability and validity of the Montreal Cognitive Assessment's auditory items (MoCA-22)

Objective: To evaluate the latent structure, internal consistency, convergent and discriminant validity, diagnostic accuracy, and criterion validity of the Montreal Cognitive Assessment's auditory items (MoCA-22), which has previously been evaluated in small samples if at all. Methods: 11,284 participants completed the MoCA over 1-2 visits to an Alzheimer Disease Research Center (Mage = 69.2, Meducation = 15.9, 57.6% women, 92.4% non-Hispanic white). MoCA-22 items were probed with alpha, omega, confirmatory factor analysis, and test-retest correlations. Scores were related to measures of neurocognition, daily functioning, behavioral-psychological symptoms (BPS), and vision performance for convergent-discriminant and criterion validity. Dementia stage was used to calculate area under the receiver operating characteristic (AUC-ROC) curves and cutoffs for mild cognitive impairment (MCI) and dementia. Results: A single-factor had good fit (CFI = .961; TLI = .945; RMSEA = .061; SRMR = .031), with good internal consistency (Omega total = .83) and test-retest consistency (ICC = .92 at 2.7 years). The strongest convergent correlations were with general cognition and executive functioning, while discriminant validity was demonstrated with its weakest and negative correlations being with BPS. There was strong classification accuracy in distinguishing MCI from normal cognition (AUC = .79; optimal cutoff point < 18), and mild-to-moderate dementia from MCI (AUC = .85; optimal cutoff point < 13). Furthermore, the MoCA-22 had negligible-to-small differences among those with and without vision limitations. Conclusions: These findings add to the evidence of the MoCA-22's utility and it serves as a useful cognitive screening tool with sound reliability and validity.

Relationships of Cognitive Measures with Cerebrospinal Fluid but Not Imaging Biomarkers of Alzheimer Disease Vary between Black and White Individuals

OBJECTIVE

Biomarkers of Alzheimer disease vary between groups of self-identified Black and White individuals in some studies. This study examined whether the relationships between biomarkers or between biomarkers and cognitive measures varied by racialized groups.

METHODS

Cerebrospinal fluid (CSF), amyloid positron emission tomography (PET), and magnetic resonance imaging measures were harmonized across four studies of memory and aging. Spearman correlations between biomarkers and between biomarkers and cognitive measures were calculated within each racialized group, then compared between groups by standard normal tests after Fisher's Z-transformations.

RESULTS

The harmonized dataset included at least one biomarker measurement from 495 Black and 2,600 White participants. The mean age was similar between racialized groups. However, Black participants were less likely to have cognitive impairment (28% vs 36%) and had less abnormality of some CSF biomarkers including CSF Aβ42/40, total tau, p-tau181, and neurofilament light. CSF Aβ42/40 was negatively correlated with total tau and p-tau181 in both groups, but at a smaller magnitude in Black individuals. CSF Aβ42/40, total tau, and p-tau181 had weaker correlations with cognitive measures, especially episodic memory, in Black than White participants. Correlations of amyloid measures between CSF (Aβ42/40, Aβ42) and PET imaging were also weaker in Black than White participants. Importantly, no differences based on race were found in correlations between different imaging biomarkers, or in correlations between imaging biomarkers and cognitive measures.

INTERPRETATION

Relationships between CSF biomarkers but not imaging biomarkers varied by racialized groups. Imaging biomarkers performed more consistently across racialized groups in associations with cognitive measures. ANN NEUROL 2024;95:495-506.

Disparate Dementia Risk Factors Are Associated with Cognitive Impairment and Rates of Decline in African Americans

OBJECTIVE

This study was undertaken to evaluate the frequency of modifiable dementia risk factors and their association with cognitive impairment and rate of decline in diverse participants engaged in studies of memory and aging.

METHODS

Modifiable dementia risk factors and their associations with cognitive impairment and cognitive decline were determined in community-dwelling African American (AA; n = 261) and non-Hispanic White (nHW; n = 193) participants who completed ≥2 visits at the Mayo Clinic Alzheimer Disease Research Center in Jacksonville, Florida. Risk factors and their associations with cognitive impairment (global Clinical Dementia Rating [CDR] ≥ 0.5) and rates of decline (CDR Sum of Boxes) in impaired participants were compared in AA and nHW participants, controlling for demographics, APOE ɛ4 status, and Area Deprivation Index.

RESULTS

Hypertension, hypercholesterolemia, obesity, and diabetes were overrepresented in AA participants, but were not associated with cognitive impairment. Depression was associated with increased odds of cognitive impairment in AA (odds ratio [OR] = 4.30, 95% confidence interval [CI] = 2.13-8.67) and nHW participants (OR = 2.79, 95% CI = 1.21-6.44) but uniquely associated with faster decline in AA participants (β = 1.71, 95% CI = 0.69-2.73, p = 0.001). Fewer AA participants reported antidepressant use (9/49, 18%) than nHW counterparts (57/78, 73%, p < 0.001). Vitamin B12 deficiency was also associated with an increased rate of cognitive decline in AA participants (β = 2.65, 95% CI = 0.38-4.91, p = 0.023).

INTERPRETATION

Modifiable dementia risk factors are common in AA and nHW participants, representing important risk mitigation targets. Depression was associated with dementia in AA and nHW participants, and with accelerated declines in cognitive function in AA participants. Optimizing depression screening and treatment may improve cognitive trajectories and outcomes in AA participants. ANN NEUROL 2024;95:518-529.

Low-Grade systemic inflammation is associated with domain-specific cognitive performance and cognitive decline in older adults: Data from the TUDA study

Studies examining the relationships between chronic inflammation, cognitive function and cognitive decline in older adults have yielded conflicting results. In a large cohort of older adults free from established dementia (n = 3270; 73.1 ± 7.9 years; 68.4% female), we evaluated the cross-sectional and longitudinal relationships between serum cytokines (IL-6, IL-10, TNF-α) and both global and domain-specific cognitive performance (Repeatable Battery for Assessment of Neuropsychological Status [RBANS]). Higher IL-6 (OR: 1.33; 1.06, 1.66, p = 0.01), TNF-α (OR: 1.35; 1.09, 1.67, p = 0.01) and IL-6:IL-10 Ratio (OR: 1.43; 1.17, 1.74, p = 0.001) were cross-sectionally associated with impaired global RBANS performance. For specific cognitive domains, greatest effect sizes were observed between higher TNF-α levels and poorer visual-spatial and attention performance. In a subset of participants (n = 725; 69.8 ± 5.5 years; 67.0% female) with repeat assessment performed at a median of 5.4 years, only higher baseline IL-6:IL-10 ratio was associated with impaired incident overall, immediate memory and visual-spatial performance. Associations were stronger in females, but not modified by age or APOE genotype.

Under-Diagnosis of Dementia with Lewy Bodies in Individuals Racialized as Black: Hypotheses Regarding Potential Contributors

Dementia with Lewy bodies (DLB) is one of the most common degenerative dementias after Alzheimer's disease (AD) dementia. DLB is under-diagnosed across populations but may be particularly missed in older Black adults. The object of this review was to examine key features of DLB and potential associations with race in order to hypothesize why DLB may be under-diagnosed in Black adults in the U.S. In terms of dementia, symptoms associated with high rates of co-pathology (e.g., AD, vascular disease) in older Black adults may obscure the clinical picture that might suggest Lewy body pathology. Research also suggests that clinicians may be predisposed to give AD dementia diagnoses to Black adults, potentially missing contributions of Lewy body pathology. Hallucinations in Black adults may be misattributed to AD or primary psychiatric disease rather than Lewy body pathology. Research on the prevalence of REM sleep behavior in diverse populations is lacking, but REM sleep behavior disorder could be under-diagnosed in Black adults due to sleep patterns or reporting by caregivers who are not bed partners. Recognition of parkinsonism could be reduced in Black adults due to clinician biases, cultural effects on self-report, and potentially underlying differences in the frequency of parkinsonism. These considerations are superimposed on structural and systemic contributions to health (e.g., socioeconomic status, education, structural racism) and individual-level social exposures (e.g., social interactions, discrimination). Improving DLB recognition in Black adults will require research to investigate reasons for diagnostic disparities and education to increase identification of core symptoms in this population.

Cognitive enrichment and education quality moderate cognitive dysfunction in black and white adults with multiple sclerosis

OBJECTIVE

To examine the extent to which three sociobehavioral proxies of cognitive reserve-years of education, education quality, and cognitive enrichment-differ in their prediction of cognitive performance among Black and White people with MS (PwMS).

METHODS

82 PwMS (Black n = 41, White n = 41) underwent a neurological examination and a neuropsychological evaluation that included tests of word recognition (Wechsler Test of Adult Reading) as well as measures of verbal memory, visuospatial memory, and processing speed (the Brief International Cognitive Assessment for MS; BICAMS). Participants rated their lifetime engagement in various cognitively-enriching activities (Cognitive Reserve Scale).

RESULTS

For the full sample, education quality and cognitive enrichment were more strongly associated with cognitive performance than were years of education. Cognitive enrichment was not associated with cognitive performance among participants with high education quality. In contrast, among participants with low education quality, cognitive enrichment was strongly associated with cognitive performance, suggesting that high engagement in cognitively-enriching activities provided similar protection to high education quality. Furthermore, among Black participants, cognitive enrichment and educational quality moderated the relationship between disability level and cognitive performance. In contrast, among White participants, cognitive enrichment did not provide additional protection beyond the buffering effect of education quality.

CONCLUSIONS

PwMS can successfully build reserve through multiple routes, including formal education or informal cognitive enrichment. Treatment for MS should incorporate cognitively-enriching activities to build resilience against cognitive decline, particularly for members of marginalized racial/ethnic groups, who are at greatest risk for poor health outcomes, and for whom years of education may not best reflect education quality.

Procedural learning, declarative learning, and working memory as predictors of learning the use of a memory compensation tool in persons with amnestic mild cognitive impairment

Persons with amnestic Mild Cognitive Impairment (aMCI) are at risk for experiencing changes in their daily functioning due to their memory impairment. The Memory Support System (MSS), a compensatory calendaring system, was developed to support functional independence in persons with aMCI (pwaMCI). This cross-sectional study examined procedural learning, declarative learning, and working memory as predictors of MSS learning efficiency in pwaMCI. Sixty pwaMCI participated in MSS training. The Serial Reaction Time Test and Mirror Tracing Test were used to assess procedural learning. The Rey Auditory Verbal Learning Test and CogState One Card Learning were used to assess declarative learning and the CogState One Back task was used to assess working memory. Multiple regression analyses were conducted to assess if procedural learning, declarative learning, and working memory predicted MSS learning efficiency. This study showed that declarative learning predicted MSS learning efficiency in pwaMCI, with less consistent results for procedural learning and non-significant results for working memory. Findings suggest that success in teaching compensatory tools is greater when training is offered in early aMCI before declarative learning skill is fully lost. Future studies should assess additional strategies to facilitate MSS learning in advanced aMCI.

Racial and ethnic differences in neuropsychiatric symptoms and progression to incident cognitive impairment among community-dwelling participants

INTRODUCTION

Neuropsychiatric symptoms (NPS) are a risk factor for dementia; however, their prevalence and severity among ethnoracial groups are poorly understood.

METHODS

We used data from the National Alzheimer's Coordinating Center (NACC) (n = 6958; ≥50 years old). Cognitively normal participants at baseline, without any NPS or dementia diagnosis, had at least one follow-up. Survival analyses assessed the hazard ratio for 12 NPS models and progression to cognitive impairment. Propensity score weighting (PSW) matched participants on age, sex, education, and race/ethnicity.

RESULTS

All 12 NPS were significantly associated with progression to cognitive impairment. In the PSW models, compared to whites, Black/African Americans were more likely to progress to cognitive impairment across all 12 NPS models, followed by Hispanic, and then Asian participants.

DISCUSSION

PSW minimized selection bias to provide robust risk estimates. There is a higher risk of progressing to cognitive impairment for ethnoracial groups with NPS. Tailored screening of NPS and cognitive impairment should incorporate patient and caregiver reports.

The importance of the dyad: Participant perspectives on sharing biomarker results in Alzheimer's disease research

BACKGROUND

In the asymptomatic "preclinical" phase of Alzheimer's disease (AD), abnormal biomarkers indicate risk for developing cognitive impairment. Biomarker information is increasingly being disclosed to participants in research settings, and biomarker testing and results disclosure will be implemented in clinical settings in the future. Biomarker disclosure has potential psychosocial benefits and harms, impacting affected individuals and their support person(s). Limited data are available about with whom research participants share their results, information that will be necessary to develop disclosure protocols and post-disclosure resources. Additionally, existing research has been conducted in largely White cohorts, limiting applicability to future clinical populations.

METHODS

We enrolled a diverse cohort of 329 adults (184 non-Hispanic White and 145 Black/African American individuals) who previously participated in AD research. After reviewing a vignette describing a hypothetical biomarker research study, participants indicated their anticipated willingness to share biomarker results with loved ones, and what reactions they anticipated from others. Using mixed-methods analysis, we identified responses related to willingness to share results.

RESULTS

A majority (78.7%) were willing to share their results with support persons. Many (59.6%) felt it would not be difficult to share, and most (90.6%) believed their loved ones would be supportive. The most common reasons for sharing were to prepare for possible future AD (41.0% of respondents), while the most common reason for not sharing was to avoid worrying loved ones (4.8% of respondents). A total of 7.3% of respondents related reasons regarding being unsure about sharing.

DISCUSSION

Participants' interest in sharing results supports integrating support persons into AD biomarker research, and may help maximize potential benefits for participants. Communicating with this "dyad" of research participant and support person(s) may improve involvement in research, and help prepare for implementation of clinical biomarker testing by clarifying communication preferences and the influence of support persons on psychosocial outcomes.

Plasma Aβ42/40 and cognitive variability are associated with cognitive function in Black Americans: Findings from the AA-FAIM cohort

Introduction

It is critical to develop more inclusive Alzheimer's disease (AD) research protocols to ensure that historically excluded groups are included in preclinical research and have access to timely diagnosis and treatment. If validated in racialized groups, plasma AD biomarkers and measures of subtle cognitive dysfunction could provide avenues to expand diversity in preclinical AD research. We sought to evaluate the utility of two easily obtained, low-burden disease markers, plasma amyloid beta (Aβ)42/40, and intra-individual cognitive variability (IICV), to predict concurrent and longitudinal cognitive performance in a sample of Black adults.

Methods

Two hundred fifty-seven Black participants enrolled in the African Americans Fighting Alzheimer's in Midlife (AA-FAIM) study underwent at least one cognitive assessment visit; a subset of n = 235 had plasma samples. Baseline IICV was calculated as the standard deviation across participants' z scores on five cognitive measures: Rey Auditory Verbal Learning Test Delayed Recall, Trail Making Test Parts A and B (Trails A and B), and Boston Naming Test. Using mixed effects regression models, we compared concurrent and longitudinal models to baseline plasma Aβ42/40 or IICV by age interactions. PrecivityAD assays quantified baseline plasma Aβ42/40.

Results

IICV was associated with concurrent/baseline performance on several outcomes but did not modify associations between age and cognitive decline. In contrast, plasma Aβ42/40 was unrelated to baseline cognitive performance, but a pattern emerged in interactions with age in longitudinal models of Trails A and B and Rey Auditory Verbal Learning Test total learning trials. Although not significant after correcting for multiple comparisons, low Aβ42/40 was associated with faster cognitive declines over time.

Discussion

Our results are promising as they extend existing findings to an Black American sample using low-cost, low-burden methods that can be implemented outside of a research center, thus supporting efforts for inclusive AD biomarker research.

Representativeness of samples enrolled in Alzheimer's disease research centers

To generalize findings on the mechanisms and prognosis in Alzheimer's disease and related dementias (ADRD), it is critical for ADRD research to be representative of the population. Sociodemographic and health characteristics across ethnoracial groups included in the National Alzheimer's Coordinating Center sample (NACC) were compared to the nationally representative Health and Retirement Study (HRS).

Baseline NACC data (n = 36,639) and the weighted 2010 HRS wave (N = 52,071,840) were included. We assessed covariate balance by calculating standardized mean differences across harmonized covariates (i.e., sociodemographic, health).

NACC participants were older, more educated, with worse subjective memory and hearing, but endorsed fewer depressive symptoms compared to HRS participants. While all racial and ethnic groups in NACC differed from HRS participants in the same way overall, these differences were further amplified between racial and ethnic groups.

NACC participants do not represent the U.S. population in key demographic and health factors, which differed by race and ethnicity.

HIGHLIGHTS

We examined selection factors included in NACC studies compared to a nationally representative sample.Selection factors included demographic and health factors and self-reported memory concerns.Results suggest that NACC participants are not representative of the U.S. population.Importantly, selection factors differed across racial and ethnic groups.Findings are suggestive of selection bias within NACC studies.

Remuneration and Recruitment of Study Participants for AD Cohort Studies From the General Public and From Minority Communities

INTRODUCTION

Offering remuneration for participation in studies of aging and Alzheimer Disease (AD) may improve recruitment, particularly among minoritized and low-income groups. But remuneration may also raise ethical problems and reduce altruistic motivations for participation.

METHODS

A nationally representative sample of Americans (N=2030) with large (N=500) Black and Hispanic oversamples was asked about willingness to participate in a longitudinal AD cohort study after random assignment of remuneration ($0, $50/visit, $100/visit). Respondents were then asked about their perceived burden, risks, and societal contribution from participation.

RESULTS

An offer of remuneration increased willingness to participate, with no difference between $50 and $100. The increase was similar across racial, ethnic, and income groups. Remuneration did not affect perceived risks or altruistic benefits. Compensation caused Whites and Hispanics, but not Blacks, to lower the perceived burden.

DISCUSSION

Modest levels of remuneration are likely to improve recruitment to AD research studies without causing collateral ethical or motivation problems. Remuneration does not differentially enhance minority recruitment.

Brief Report: An Evaluation of Item Bias on the Functional Activities Questionnaire

OBJECTIVE

To evaluate whether the Functional Activities Questionnaire (FAQ), a commonly used measure of functional status in neurodegenerative disease research, performs equivalently across demographically diverse subgroups of participants.

METHOD

The FAQs from 30,613 National Alzheimer's Coordinating Center participants were evaluated with a hybrid graded response model-logistic ordinal regression approach to determine the presence of differential item functioning (DIF) within five demographic groups: education, ethnicity, race, language, and sex.

RESULTS

Measurable DIF was observed for FAQ items in all groups; however, measures of effect size, latent trait distributions, and item characteristic curves suggested that the impact was minimal for research and practice.

CONCLUSIONS

The FAQ is able to provide minimally biased assessments of daily functioning across diverse participants, suggesting potential value for offsetting disparities in diagnosis and treatment.

External Validation of the eRADAR Risk Score for Detecting Undiagnosed Dementia in Two Real-World Healthcare Systems

BACKGROUND

Fifty percent of people living with dementia are undiagnosed. The electronic health record (EHR) Risk of Alzheimer's and Dementia Assessment Rule (eRADAR) was developed to identify older adults at risk of having undiagnosed dementia using routinely collected clinical data.

OBJECTIVE

To externally validate eRADAR in two real-world healthcare systems, including examining performance over time and by race/ethnicity.

DESIGN

Retrospective cohort study PARTICIPANTS: 129,315 members of Kaiser Permanente Washington (KPWA), an integrated health system providing insurance coverage and medical care, and 13,444 primary care patients at University of California San Francisco Health (UCSF), an academic medical system, aged 65 years or older without prior EHR documentation of dementia diagnosis or medication.

MAIN MEASURES

Performance of eRADAR scores, calculated annually from EHR data (including vital signs, diagnoses, medications, and utilization in the prior 2 years), for predicting EHR documentation of incident dementia diagnosis within 12 months.

KEY RESULTS

A total of 7631 dementia diagnoses were observed at KPWA (11.1 per 1000 person-years) and 216 at UCSF (4.6 per 1000 person-years). The area under the curve was 0.84 (95% confidence interval: 0.84-0.85) at KPWA and 0.79 (0.76-0.82) at UCSF. Using the 90th percentile as the cut point for identifying high-risk patients, sensitivity was 54% (53-56%) at KPWA and 44% (38-51%) at UCSF. Performance was similar over time, including across the transition from International Classification of Diseases, version 9 (ICD-9) to ICD-10 codes, and across racial/ethnic groups (though small samples limited precision in some groups).

CONCLUSIONS

eRADAR showed strong external validity for detecting undiagnosed dementia in two health systems with different patient populations and differential availability of external healthcare data for risk calculations. In this study, eRADAR demonstrated generalizability from a research sample to real-world clinical populations, transportability across health systems, robustness to temporal changes in healthcare, and similar performance across larger racial/ethnic groups.

Let's Not Repeat History's Mistakes: Two Cautions to Scientists on the Use of Race in Alzheimer's Disease and Alzheimer's Disease Related Dementias Research

Alzheimer's disease and Alzheimer's disease related dementias (AD/ADRD) research has advanced gene and biomarker technologies to aid identification of individuals at risk for dementia. This innovation is a lynchpin in development of disease-modifying therapies. The emerging science could transform outcomes for patients and families. However, current limitations in the racial representation and inclusion of racial diversity in research limits the relevance of these technologies: AD/ADRD research cohorts used to define biomarker cutoffs are mostly White, despite clinical and epidemiologic research that shows Black populations are among those experiencing the greatest burdens of AD/ADRD. White cohorts alone are insufficient to characterize heterogeneity in disease and in life experiences that can alter AD/ADRD's courses. The National Institute on Aging (NIA) has called for increased racial diversity in AD/ADRD research. While scientists are working to implement NIA's plan to build more diverse research cohorts, they are also seeking out opportunities to consider race in AD/ADRD research. Recently, scientists have posed two ways of including race in AD/ADRD research: ancestry-based verification of race and race-based adjustment of biomarker test results. Both warrant careful examination for how they are impacting AD/ADRD science with respect to specific study objectives and the broader mission of the field. If these research methods are not grounded in pursuit of equity and justice, biases they introduce into AD/ADRD science could perpetuate, or even worsen, disparities in AD/ADRD research and care.

Association of Traumatic Brain Injury with Late Life Neuropathological Outcomes in a Community-Based Cohort

BACKGROUND

Prior studies into the association of head trauma with neuropathology have been limited by incomplete lifetime neurotrauma exposure characterization.

OBJECTIVE

To investigate the neuropathological sequelae of traumatic brain injury (TBI) in an autopsy sample using three sources of TBI ascertainment, weighting findings to reflect associations in the larger, community-based cohort.

METHODS

Self-reported head trauma with loss of consciousness (LOC) exposure was collected in biennial clinic visits from 780 older adults from the Adult Changes in Thought study who later died and donated their brain for research. Self-report data were supplemented with medical record abstraction, and, for 244 people, structured interviews on lifetime head trauma. Neuropathology outcomes included Braak stage, CERAD neuritic plaque density, Lewy body distribution, vascular pathology, hippocampal sclerosis, and cerebral/cortical atrophy. Exposures were TBI with or without LOC. Modified Poisson regressions adjusting for age, sex, education, and APOE ɛ4 genotype were weighted back to the full cohort of 5,546 participants.

RESULTS

TBI with LOC was associated with the presence of cerebral cortical atrophy (Relative Risk 1.22, 95% CI 1.02, 1.42). None of the other outcomes was associated with TBI with or without LOC.

CONCLUSION

TBI with LOC was associated with increased risk of cerebral cortical atrophy. Despite our enhanced TBI ascertainment, we found no association with the Alzheimer's disease-related neuropathologic outcomes among people who survived to at least age 65 without dementia. This suggests the pathophysiological processes underlying post-traumatic neurodegeneration are distinct from the hallmark pathologies of Alzheimer's disease.

Pathological functional impairment: Neuropsychological correlates of the shared variance between everyday functioning and brain volumetrics

Objective

Given that several non-cognitive factors can contribute to difficulties with everyday functioning, examining the extent to which cognition is associated with brain-related changes in everyday functioning is critical to accurate characterization of cognitive disorders. In this study, we examined neuropsychological correlates of the shared variance between everyday functioning and pathological indicators of cognitive aging using MRI brain volumetrics.

Participants and methods

Participants were 600 adults aged 55 and older without dementia [432 cognitively normal; 168 mild cognitive impairment (MCI)] from the National Alzheimer's Coordinating Center cohort who underwent neuropsychological testing, informant-rated everyday functioning, and brain MRI scanning at baseline. The shared variance between everyday functioning and brain volumetrics (i.e., hippocampal volume, white matter hyperintensity volume) was extracted using the predicted value from multiple regression. The shared variance was used as an indicator of pathological everyday functional impairment. The residual variance from the regression analysis was used to examine functional reserve.

Results

Larger white matter hyperintensity volumes (p = 0.002) and smaller hippocampal volumes (p < 0.001) were significantly correlated with worse informant-rated everyday functioning. Among individuals with MCI, worse performances on delayed recall (p = 0.013) and category fluency (p = 0.012) were significantly correlated with pathological functional impairment in multiple regression analysis. In the cognitively normal group, only worse auditory working memory (i.e., digit span backward; p = 0.025) significantly correlated with pathological functioning. Functional reserve was inversely related to anxiety (p < 0.001) in the MCI group and was associated with depressive symptoms (p = 0.003) and apathy (p < 0.001) in the cognitively normal group.

Conclusion

Subtle brain-related everyday functioning difficulties are evident in MCI and track with expected preclinical Alzheimer's disease cognitive phenotypes in this largely amnestic sample. Our findings indicate that functional changes occur early in the disease process and that interventions to target neuropsychiatric symptoms may help to bolster functional reserve in those at risk.

Racial differences in longitudinal Alzheimer's disease biomarkers among cognitively normal adults

INTRODUCTION

Longitudinal changes in Alzheimer's disease (AD) biomarkers, including cerebrospinal fluid (CSF) analytes, amyloid uptakes from positron emission tomography (PET), structural outcomes from magnetic resonance imaging (MRI), and cognition, have not been compared between Blacks and Whites.

METHODS

A total of 179 Blacks and 1180 Whites who were cognitively normal at baseline and had longitudinal data from at least one biomarker modality were analyzed for the annual rates of change.

RESULTS

CSF amyloid beta (Aβ)42/Aβ40 declined more slowly (P = .0390), and amyloid (PET) accumulated more slowly (P = .0157), in Blacks than Whites. CSF Aβ42 changed in opposite directions over time between Blacks and Whites (P = .0039). The annual increase in CSF total tau and phosphorylated tau181 for Blacks was about half of that for Whites.

DISCUSSION

Longitudinal racial differences in amyloid biomarkers are observed. It will be important to comprehensively and prospectively examine the effects of apolipoprotein E genotype and sociocultural factors on these differences.

The complex relationship between depression and progression to incident cognitive impairment across race and ethnicity

INTRODUCTION

We examined baseline differences in depression and antidepressant use among cognitively normal older adults in five ethnoracial groups and assessed whether depression predicted a faster progression to incident cognitive impairment across groups.

METHODS

Data from the National Alzheimer's Coordinating Center (n = 8168) were used to examine differences between non-Hispanic Whites (nHW), African Americans (AA), Hispanics, Asians, and American Indian and Alaskan Natives in cross-sectional and longitudinal models.

RESULTS

AA had a lower risk of depression compared to nHW at baseline. No statistical interactions were noted between ethnoracial groups and depression. However, depression independently predicted a faster progression to incident cognitive impairment. Hispanics and Asian participants had a higher hazard for progression compared to nHW.

DISCUSSION

Previously established risk factors between depression and dementia were not found among AA and nHW participants. The relationship between depression and ethnoracial groups is complex and suggests differential effects on progression from cognitive normality to impairment.

Estimating the Prevalence of Dementia and Mild Cognitive Impairment in the US: The 2016 Health and Retirement Study Harmonized Cognitive Assessment Protocol Project

Importance

Nationally representative data are critical for understanding the causes, costs, and outcomes associated with dementia and mild cognitive impairment (MCI) in the US and can inform policies aimed at reducing the impact of these conditions on patients, families, and public programs. The nationally representative Health and Retirement Study (HRS) is an essential resource for such data, but the HRS substudy providing dementia diagnostic information was fielded more than 20 years ago and more recent data are needed.

Objective

The Harmonized Cognitive Assessment Protocol (HCAP) was developed to update national estimates of the prevalence of MCI and dementia in the US and examine differences by age, race, ethnicity, and sex.

Design, Setting, and Participants

HRS is an ongoing longitudinal nationally representative study of people 51 years and older with staggered entry dates from 1992 to 2022 and follow-up ranging from 4 to 30 years. HCAP is a cross-sectional random sample of individuals in HRS who were 65 years or older in 2016. Of 9972 age-eligible HRS participants, 4425 were randomly selected for HCAP, and 3496 completed a comprehensive neuropsychological test battery and informant interview, none of whom were excluded. Dementia and MCI were classified using an algorithm based on standard diagnostic criteria and comparing test performance to a robust normative sample.

Exposures

Groups were stratified by age, sex, education, race, and ethnicity.

Main Outcomes and Measures

National prevalence estimates using population weights.

Results

The mean (SD) age of the study population sample (N = 3496) was 76.4 (7.6) years, and 2095 participants (60%) were female. There were 551 participants who self-identified as Black and not Hispanic (16%), 382 who self-identified as Hispanic regardless of race (16%), 2483 who self-identified as White and not Hispanic (71%), and 80 who self-identified as another race (2%), including American Indian or Alaska Native, Asian, Native Hawaiian or Pacific Islander, or another self-described race. A total of 393 individuals (10%; 95% CI, 9-11) were classified as having dementia and 804 (22%; 95% CI, 20-24) as having MCI. Every 5-year increase in age was associated with higher risk of dementia (weighted odds ratio [OR], 1.95 per 5-year age difference; 95%, CI, 1.77-2.14) and MCI (OR, 1.17 per 5-year age difference, 95% CI, 1.09-1.26). Each additional year of education was associated with a decrease in risk of dementia (OR, 0.93 per year of school, 95% CI, 0.89-0.97) and MCI (OR, 0.94, 95% CI, 0.91-0.97). Dementia was more common among non-Hispanic Black individuals (OR, 1.81; 95% CI, 1.20-2.75) and MCI in Hispanic individuals (OR, 1.42; 95% CI, 1.03-1.96) compared with non-Hispanic White individuals. Other group comparisons by race and ethnicity were not possible owing to small numbers. No differences in prevalence were found between female individuals and male individuals.

Conclusions and Relevance

Using a comprehensive neuropsychological test battery and large sample, the national prevalence of dementia and MCI in 2016 found in this cross-sectional study was similar to that of other US-based studies, indicating a disproportionate burden of dementia and MCI among older Black and Hispanic adults and those with lower education.

Accounting for lack of representation in dementia research: Generalizing KHANDLE study findings on the prevalence of cognitive impairment to the California older population

INTRODUCTION

Most dementia studies are not population-representative; statistical tools can be applied to samples to obtain critically-needed population-representative estimates, but are not yet widely used.

METHODS

We pooled data from the Kaiser Healthy Aging and Diverse Life Experiences (KHANDLE) study and the California Behavioral Risk Factor Surveillance System (CA-BRFSS), a population-representative study. Using weights accounting for sociodemographic/health differences between KHANDLE and CA-BRFSS, we estimated cognitive impairment prevalence and age- and sex-adjusted racial/ethnic inequalities in California adults 65+ without prior dementia diagnosis.

RESULTS

After weighting KHANDLE, the estimated cognitive impairment prevalence in California was 20.3% (95% confidence interval 17.8-23.0); unweighted prevalence was 24.8% (23.1%-26.6%). Inequalities (larger prevalences) were observed among Black and Asian groups versus whites.

DISCUSSION

We used a novel statistical approach to estimate population-representative cognitive impairment prevalence and inequalities. Such statistical tools can help obtain population-representative estimates from existing studies and inform efforts to reduce racial/ethnic disparities.

Moving beyond disclosure: Stages of care in preclinical Alzheimer's disease biomarker testing

Alzheimer's disease (AD) begins with an asymptomatic "preclinical" phase, in which abnormal biomarkers indicate risk for developing cognitive impairment. Biomarker information is increasingly being disclosed in research settings, and is moving toward clinical settings with the development of cheaper and non-invasive testing. Limited research has focused on the safety and psychological effects of disclosing biomarker results to cognitively unimpaired adults. However, less is known about how to ensure equitable access and robust counseling for decision-making before testing, and how to effectively provide long-term follow-up and risk management after testing. Using the framework of Huntington's disease, which is based on extensive experience with disclosing and managing risk for a progressive neurodegenerative condition, this article proposes a conceptual model of pre-disclosure, disclosure, and post-disclosure phases for AD biomarker testing. Addressing research questions in each phase will facilitate the transition of biomarker testing into clinical practice.

Perceptions of Research Burden and Retention Among Participants in ADRC Cohorts

OBJECTIVES

Alzheimer disease (AD) and related dementias clinical research is associated with significant participant burden. The Perceived Research Burden Assessment (PeRBA) measures participants' perceptions of logistical, psychological, and physical burdens. The purpose of this study was to assess PeRBA's psychometric properties, perceptual sources, and behavioral consequences with participants in a multisite study of participant retention in longitudinal cohort studies of Alzheimer disease and related dementias.

DESIGN

Multicenter mixed methods.

SETTING

In-person or phone.

PARTICIPANTS

A total of 443 participants at 4 NIA-funded Alzheimer Disease Research Centers (ADRCs) were randomly selected and invited to participate if they were 45 years of age or more, enrolled in longitudinal studies, and had a Clinical Dementia Rating Scale global score ≤1.

MEASUREMENTS

Participants completed a 20-minute survey including the 21-item PeRBA about their research participation.

RESULTS

PeRBA demonstrated high-internal consistency and convergent validity. PeRBA scores correlated with expected perceptual factors. Higher PeRBA scores were associated with lower attendance and higher dropout rates.

CONCLUSIONS

PeRBA can be used by researchers to identify participants who may feel overburdened and tailor approaches and strategies to support participants in longitudinal AD studies, maximizing participation, and reducing dropout. Making efforts to increase participants' understanding of study procedures, and building and maintaining trust throughout the study, can contribute to reducing perceived burden and potentially increasing retention in longitudinal AD studies.

Emergency department care transition barriers: A qualitative study of care partners of older adults with cognitive impairment

INTRODUCTION

After emergency department (ED) discharge, persons living with cognitive impairment (PLWCI) and their care partners are particularly at risk for adverse outcomes. We sought to identify the barriers experienced by care partners of PLWCI during ED discharge care transitions.

METHODS

We conducted a qualitative study of 25 care partners of PLWCI discharged from four EDs. We used the validated 4AT and care partner-completed AD8 screening tools, respectively, to exclude care partners of older adults with concern for delirium and include care partners of older adults with cognitive impairment. We conducted recorded, semi-structured interviews using a standardized guide, and two team members coded and analyzed all professional transcriptions to identify emerging themes and representative quotations.

RESULTS

Care partners' mean age was 56.7 years, 80% were female, and 24% identified as African American. We identified four major barriers regarding ED discharge care transitions among care partners of PLWCI: (1) unique care considerations while in the ED setting impact the perceived success of the care transition, (2) poor communication and lack of care partner engagement was a commonplace during the ED discharge process, (3) care partners experienced challenges and additional responsibilities when aiding during acute illness and recovery phases, and (4) navigating the health care system after an ED encounter was perceived as difficult by care partners.

DISCUSSION

Our findings demonstrate critical barriers faced during ED discharge care transitions among care partners of PLWCI. Findings from this work may inform the development of novel care partner-reported outcome measures as well as ED discharge care transition interventions targeting care partners.

Vulnerability to Hypertension Is a Major Determinant of Racial Disparities in Alzheimer's Disease Risk

BACKGROUND

Higher incidence levels of Alzheimer's disease (AD) in Black Americans are well documented. However, quantitative explanations of this disparity in terms of risk-factor diseases acting through well-defined pathways are lacking.

METHODS

We applied a Blinder-Oaxaca-based algorithm modified for censored data to a 5% random sample of Medicare beneficiaries age 65+ to explain Black/White disparities in AD risk in terms of differences in exposure and vulnerability to morbidity profiles based on 10 major AD-risk-related diseases.

RESULTS

The primary contribution to racial disparities in AD risk comes from morbidity profiles that included hypertension with about 1/5th of their contribution due to differences in prevalence (exposure effect) and 4/5ths to differences in the effects of the morbidity profile on AD risk (vulnerability effect). In total, disease-related effects explained a higher proportion of AD incidence in Black Americans than in their White counterparts.

CONCLUSIONS

Disease-related causes may represent some of the most straightforward targets for targeted interventions aimed at the reduction of racial disparities in health among US older adults. Hypertension is a manageable and potentially preventable condition responsible for the majority of the Black/White differences in AD risk, making mitigation of the role of this disease in engendering higher AD incidence in Black Americans a prominent concern.

Black and White individuals differ in dementia prevalence, risk factors, and symptomatic presentation

INTRODUCTION

Although dementia prevalence differs by race, it remains unclear whether cognition and neuropsychiatric symptom severity differ between Black and White individuals with dementia.

METHODS

Using National Alzheimer's Coordinating Center (NACC) data, we evaluated dementia prevalence in non-Hispanic Black and White participants and compared their clinicodemographic characteristics. We examined race differences in cognition, neuropsychiatric symptoms, and functional abilities in participants with dementia using multivariable linear and logistic regression models.

RESULTS

We included 5,700 Black and 31,225 White participants across 39 Alzheimer's Disease Research Centers. Of these, 1,528 (27%) Black and 11,267 (36%) White participants had dementia diagnoses. Despite having lower dementia prevalence, risk factors were more prevalent among Black participants. Black participants with dementia showed greater cognitive deficits, neuropsychiatric symptoms/severity, and functional dependence.

DISCUSSION

Despite lower dementia prevalence, Black participants with dementia had more dementia risk factors, as well as greater cognitive impairment and neuropsychiatric symptom severity than White participants.

Psychological well-being and cognitive aging in Black, Native American, and White Alzheimer's Disease Research Center participants

Psychological well-being is associated with cognition in later life but has not been examined across diverse populations-including minoritized communities at disproportionately high risk of dementia. Further, most previous work has not been able to examine links between specific facets of psychological well-being and performance within distinct cognitive domains that can capture subclinical impairment. Using a well-characterized sample followed through enrollment in an NIH-funded Alzheimer's Disease Center, we sought to test these associations within three racial groups at baseline. Participants were N = 529 cognitively unimpaired Black, American Indian/Alaska Native (AI/AN), and white middle-aged and older adults (mean age = 63.6, SD = 8.1, range = 45-88 years) enrolled in the Wisconsin Alzheimer's Disease Research Center's Clinical Core. Predictors included validated NIH Toolbox Emotion Battery scales assessing positive affect, general life satisfaction, and meaning and purpose. Outcomes included performance on widely used tests of executive functioning and episodic memory. We conducted race-stratified regression models to assess within-group relationships. Black and AI/AN participants reported lower life satisfaction than white participants. Racial disparities were not observed for positive affect or meaning and purpose scores. Across groups, life satisfaction predicted better executive functioning. Similar associations were observed for positive affect in Black and AI/AN samples but not among whites. In general, well-being measures were not related to performance on tests of episodic memory. Our results highlight well-being as a potentially important determinant of late-life cognitive health, particularly executive functioning, that is modifiable if older adults are connected with appropriate resources and supports. Further, psychological well-being may represent a potent target for brain health interventions tailored for Black and Native communities.

Effect of Race on Prediction of Brain Amyloidosis by Plasma Aβ42/Aβ40, Phosphorylated Tau, and Neurofilament Light

BACKGROUND AND OBJECTIVES

To evaluate whether plasma biomarkers of amyloid (Aβ42/Aβ40), tau (p-tau181 and p-tau231), and neuroaxonal injury (neurofilament light chain [NfL]) detect brain amyloidosis consistently across racial groups.

METHODS

Individuals enrolled in studies of memory and aging who self-identified as African American (AA) were matched 1:1 to self-identified non-Hispanic White (NHW) individuals by age, APOE ε4 carrier status, and cognitive status. Each participant underwent blood and CSF collection, and amyloid PET was performed in 103 participants (68%). Plasma Aβ42/Aβ40 was measured by a high-performance immunoprecipitation-mass spectrometry assay. Plasma p-tau181, p-tau231, and NfL were measured by Simoa immunoassays. CSF Aβ42/Aβ40 and amyloid PET status were used as primary and secondary reference standards of brain amyloidosis, respectively.

RESULTS

There were 76 matched pairs of AA and NHW participants (n = 152 total). For both AA and NHW groups, the median age was 68.4 years, 42% were APOE ε4 carriers, and 91% were cognitively normal. AA were less likely than NHW participants to have brain amyloidosis by CSF Aβ42/Aβ40 (22% vs 43% positive; p = 0.003). The receiver operating characteristic area under the curve of CSF Aβ42/Aβ40 status with the plasma biomarkers was as follows: Aβ42/Aβ40, 0.86 (95% CI 0.79-0.92); p-tau181, 0.76 (0.68-0.84); p-tau231, 0.69 (0.60-0.78); and NfL, 0.64 (0.55-0.73). In models predicting CSF Aβ42/Aβ40 status with plasma Aβ42/Aβ40 that included covariates (age, sex, APOE ε4 carrier status, race, and cognitive status), race did not affect the probability of CSF Aβ42/Aβ40 positivity. In similar models based on plasma p-tau181, p-tau231, or NfL, AA participants had a lower probability of CSF Aβ42/Aβ40 positivity (odds ratio 0.31 [95% CI 0.13-0.73], 0.30 [0.13-0.71], and 0.27 [0.12-0.64], respectively). Models of amyloid PET status yielded similar findings.

DISCUSSION

Models predicting brain amyloidosis using a high-performance plasma Aβ42/Aβ40 assay may provide an accurate and consistent measure of brain amyloidosis across AA and NHW groups, but models based on plasma p-tau181, p-tau231, and NfL may perform inconsistently and could result in disproportionate misdiagnosis of AA individuals.

Health Disparities in Dementia

PURPOSE OF REVIEW

Causes of health disparities in Alzheimer disease and related dementias (ADRD) in the United States are multifactorial. This article contextualizes health disparities as they relate to the neurodegenerative processes of ADRD.

RECENT FINDINGS

Older adults' life expectancy has increased such that a 65-year-old is expected to live 19 or more years and an 85-year-old can expect to live, on average, 6 to 7 years longer. Individuals of certain ethnoracial groups (Black, Hispanic/Latino, American Indian/Alaska Native, and Native Hawaiian/Pacific Islander) may be at a higher risk of incident ADRD compared to non-Hispanic/Latino White people. These differences in a higher risk of ADRD across ethnoracial groups persist despite no statistically significant differences in the rate of cognitive decline over time. The intersectionality of social determinants of health, experiences with discrimination and oppression, and access to care are related to the issue of justice and the risk for and expression of ADRD. The theoretical frameworks of various health disparities provide organized approaches to tracking the progression of health disparities for diverse patients.

SUMMARY

ADRD health disparities are complex. Neurologists and their care teams must consider the main reasons for clinical ADRD evaluations of members of ethnoracial groups and the factors that may impact patient adherence and compliance with diagnostic and management recommendations.

Traversing the Aging Research and Health Equity Divide: Toward Intersectional Frameworks of Research Justice and Participation

Meaningful reductions in racial and ethnic inequities in chronic diseases of aging remain unlikely without major advancements in the inclusion of minoritized populations in aging research. While sparse, studies investigating research participation disparities have predominantly focused on individual-level factors and behavioral change, overlooking the influence of study design, structural factors, and social determinants of health on participation. This is also reflected in conventional practices that consistently fail to address established participation barriers, such as study requirements that impose financial, transportation, linguistic, and/or logistical barriers that disproportionately burden participants belonging to minoritized populations. These shortcomings not only risk exacerbating distrust toward research and researchers, but also introduce significant selection biases, diminishing our ability to detect differential mechanisms of risk, resilience, and response to interventions across subpopulations. This forum article examines the intersecting factors that drive both health inequities in aging and disparate participation in aging research among minoritized populations. Using an intersectional, social justice, and emancipatory lens, we characterize the role of social determinants, historical contexts, and contemporaneous structures in shaping research accessibility and inclusion. We also introduce frameworks to accelerate transformative theoretical approaches to fostering equitable inclusion of minoritized populations in aging research.

Assessing Equitable Inclusion of Underrepresented Older Adults in Alzheimer's Disease, Related Cognitive Disorders, and Aging-Related Research: A Scoping Review

BACKGROUND AND OBJECTIVES

The rapidly aging and diversifying U.S. population is challenged by increases in prevalence of Alzheimer's disease (AD) and aging-related disorders. We conducted a scoping review to assess equitable inclusion of diverse older adult populations in aging research focused on National Institutes of Health (NIH)-sponsored research.

RESEARCH DESIGN AND METHODS

The scoping review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA-Scr) Protocol. The search was limited to NIH-funded studies focusing on aging, AD and Alzheimer's disease-related dementias (ADRD) and included adults aged 55+. The priority populations and health disparities put forth by the NIA Health Disparities Framework serve as a model for guiding inclusion criteria and for interpreting the representation of these underrepresented groups, including racial ethnic minorities, socioeconomically disadvantaged, rural populations, groups with disabilities, and LGBTQ communities.

RESULTS

Our search identified 1,177 records, of which 436 articles were included in the analysis. Inclusion of individuals with ADRD and mild cognitive impairment, racial ethnic minorities, rural populations, socioeconomically disadvantaged, groups with disabilities, and LGBTQ communities were poorly specified in most studies. Studies used multiple recruitment methods, conducting studies in community settings (59%) and hospitals/clinics (38%) most frequently. Incentives, convenience factors, and sustained engagement via community-based and care partners were identified as key strategies for improved retention.

DISCUSSION AND IMPLICATIONS

This scoping review identified gaps in existing literature and aims for future work, including stronger research focus on, better inclusion of, and improved data collection and reporting of older adults from underrepresented groups.

Predictors of Willingness to Enroll in Hypothetical Alzheimer Disease Biomarker Studies that Disclose Personal Results

INTRODUCTION

We examined factors related to willingness to enroll in hypothetical Alzheimer disease (AD) biomarker studies.

METHODS

Using linear regression, we assessed the relationship among enrollment willingness and demographics, family dementia history, research attitudes, concern about AD, experiences of discrimination, and belief in AD risk modifiability. Inductive coding was used to assess qualitative data.

RESULTS

In middle-aged and older adult AD research participants (n=334), willingness to enroll in biomarker studies was driven by biomarker collection method, research attitudes, and disclosure of personal results. Predictors of willingness were similar for Black and White participants. Themes associated with increased willingness included a desire to learn biomarker results and support research.

DISCUSSION

Research attitudes were an important predictor of biomarker study willingness regardless of race. As seen elsewhere, Black participants were more hesitant to participate in biomarker research. Disclosure of biomarker results/risk can bolster willingness to enroll in biomarker studies, particularly for Black participants.

Laptop-Administered NIH Toolbox and Cogstate Brief Battery in Community-Dwelling Black Adults: Unexpected Pattern of Cognitive Performance between MCI and Healthy Controls

OBJECTIVE

Black adults are approximately twice as likely to develop Alzheimer's disease (AD) than non-Hispanic Whites and access diagnostic services later in their illness. This dictates the need to develop assessments that are cost-effective, easily administered, and sensitive to preclinical stages of AD, such as mild cognitive impairment (MCI). Two computerized cognitive batteries, NIH Toolbox-Cognition and Cogstate Brief Battery, have been developed. However, utility of these measures for clinical characterization remains only partially determined. We sought to determine the convergent validity of these computerized measures in relation to consensus diagnosis in a sample of MCI and healthy controls (HC).

METHOD

Participants were community-dwelling Black adults who completed the neuropsychological battery and other Uniform Data Set (UDS) forms from the AD centers program for consensus diagnosis (HC = 61; MCI = 43) and the NIH Toolbox-Cognition and Cogstate batteries. Discriminant function analysis was used to determine which cognitive tests best differentiated the groups.

RESULTS

NIH Toolbox crystallized measures, Oral Reading and Picture Vocabulary, were the most sensitive in identifying MCI apart from HC. Secondarily, deficits in memory and executive subtests were also predictive. UDS neuropsychological test analyses showed the expected pattern of memory and executive functioning tests differentiating MCI from HC.

CONCLUSIONS

Contrary to expectation, NIH Toolbox crystallized abilities appeared preferentially sensitive to diagnostic group differences. This study highlights the importance of further research into the validity and clinical utility of computerized neuropsychological tests within ethnic minority populations.

Diagnostic accuracy and differential associations between ratings of functioning and neuropsychological performance in non-Hispanic Black and White older adults

ObjectiveWe recently demonstrated that relative to consensus-based methods, actuarial methods may improve diagnostic accuracy across the continuum of cognitively normal (CN), mild cognitive impairment (MCI), and dementia in the overall National Alzheimer's Coordinating Center (NACC) cohort. However, the generalizability and comparative utility of current methods of diagnosing MCI and dementia due to Alzheimer's disease and related disorders (ADRD) are significantly understudied in non-Hispanic Black (NHB) older adults. Thus, we extended our previous investigation to more specifically explore the utility of consensus-based and actuarial diagnostic methods in NHB older adults.Method: We compared baseline consensus and actuarial diagnostic rates, and associations of ratings of functioning with neuropsychological performance and diagnostic outcomes, in NHB (n = 963) and non-Hispanic White (NHW; n = 4577) older adults in the NACC cohort.Results: 60.0% of the NHB subsample, versus 29.2% of the NHW subsample, included participants who met actuarial criteria for MCI despite being classified as CN or impaired-not-MCI per consensus. Additionally, associations between ratings of functioning and neuropsychological performance were less consistent in NHB participants than in NHW participants.Conclusions: Our results provide evidence of differential degrees of association between reported functioning and neuropsychological performance in NHB and NHW older adults, which may contribute to racial group differences in diagnostic rates, and prompt consideration of the strengths and weaknesses of consensus-based and actuarial diagnostic approaches in assessing neurocognitive functioning in NHB older adults.

Examination of race and gender differences in predictors of neuropsychological decline and development of Alzheimer's disease

ObjectiveBlack adults are diagnosed with Alzheimer's disease (AD) at higher rates than White adults. Biopsychosocial risk factors that differentially affect individuals by race, including health, education, and APOE e4, may explain these findings. Some research suggests that the risk for AD associated with the APOE e4 allele may differ by race. Gender differences in AD have also been identified but remain understudied. We examined race, APOE status, vascular risk factors, education, and the interaction of APOE e4 status and race as predictors of cognitive decline and the development of Alzheimer's disease between genders in a large longitudinal sample of older adults. Methods: Participants (N = 4336) were selected from the National Alzheimer's Coordinating Center's Uniform Data Set who completed measures of verbal fluency, naming, and immediate/delayed story memory across 5 years. Analyses were stratified by gender. Follow up interactions examined statistical significance of differences. Results: APOE e4 by race interactions were largely non-significant and dropped from most models. When controlling for health, education, referral source, and Uniform Data Set form (when applicable), few racial differences in cognitive performance over time emerged. Black participants obtained lower scores than White participants on a majority of baseline measures. Race findings did not differ by gender. Hypertension was more strongly predictive of decline in delayed memory among women. Conclusions: Analyses did not support that APOE e4 differentially affects Black individuals. Hypertension may be a more relevant risk factor among women. Results raise questions regarding the accuracy of baseline scores in predicting decline for Black individuals.

Predictors of Incident Mild Cognitive Impairment and Its Course in a Diverse Community-Based Population

BACKGROUND AND OBJECTIVES

To investigate sociodemographic and medical predictors of incident mild cognitive impairment (MCI) and subsequent course of MCI at follow-up, including sustained MCI diagnosis, classification as cognitively normal, and progression to dementia.

METHODS

Within a community-based cohort, diagnoses of MCI were made with a published algorithm. Diagnosis of dementia was based on clinical consensus. Cox regressions estimated hazard ratios of incident MCI associated with several predictors. Modified Poisson regressions estimated relative risks associated with predictors of diagnostic status at follow-up after incidence.

RESULTS

Among 2,903 cognitively normal participants at baseline, 752 developed MCI over an average of 6.3 (SD 4.5) years (incidence rate 56 per 1,000 person-years). Presence of APOE ε4 and higher medical burden increased risk of incident MCI, while more years of education, more leisure activities, and higher income decreased this risk. Of the incident MCI cases, after an average of 2.4 years of follow-up, 12.9% progressed to dementia, 9.6% declined in functioning and did not meet the algorithmic criteria for MCI but did not meet the clinical criteria for dementia, 29.6% continued to meet MCI criteria, and 47.9% no longer met MCI criteria. Multidomain MCI, presence of APOE ε4, depressive symptoms, and antidepressant use increased the risk of progression to dementia.

DISCUSSION

This community-based study showed that almost half of the individuals with incident MCI diagnoses were classified as cognitively normal at follow-up. Predictors of incident MCI demonstrably differed from those of subsequent MCI course; these findings can refine expectations for cognitive and functional course of those presenting with MCI.

Predictors of Mortality in Individuals with Dementia in the National Alzheimer's Coordinating Center

BACKGROUND

Dementia is one of the top causes of death worldwide, but individuals with dementia and their caregivers report that knowing what to expect, including regarding approaching end of life, is an unmet need.

OBJECTIVE

To identify predictors of death in individuals with Alzheimer disease (AD) dementia, Lewy body dementia (LBD), vascular dementia, and frontotemporal dementia.

METHODS

The study used data from National Alzheimer's Coordinating Center participants with dementia and an etiologic diagnosis of AD, Lewy body disease, frontotemporal lobar degeneration (FTLD, with or without motor neuron disease), or vascular dementia. Analyses included median survival across dementia types and predictors of death at 5 years based on baseline demographics and clinical measure performance. Five-year survival probability tables were stratified by predictor values.

RESULTS

Individuals with AD had the longest survival (median 6 years), followed by FTLD (5 years), and vascular dementia and LBD (each 4 years). The strongest predictors of death for the full cohort were dementia type (higher risk with non-AD dementias), sex (higher risk with male sex), and race and ethnicity (higher risk with white and non-Hispanic participants). Age was associated with higher mortality risk across the non-Alzheimer dementias; other significant associations included worse cognitive status (FTLD, LBD) and more depression (LBD).

CONCLUSION

Results can help clinicians counsel individuals with dementia and families regarding average dementia trajectories; findings regarding individual risk factors can aid individualizing expectations. Further research is needed to investigate drivers of mortality in the non-AD dementias to improve counseling and help identify potentially modifiable factors.

What Influences the Willingness of Blacks and African Americans to Enroll in Preclinical Alzheimer's Disease Biomarker Research? A Qualitative Vignette Analysis

BACKGROUND

Alzheimer's disease (AD) begins with an asymptomatic "preclinical" phase, in which abnormal biomarkers indicate risk for developing cognitive impairment. Research is increasingly focused on validating biomarkers to improve reliable diagnosis and timely clinical treatment of AD. Most preclinical biomarker research lacks adequate representation of Black/African American and other racially and ethnically minoritized individuals, limiting the applicability of data to these groups. This may exacerbate existing disparities by hindering diagnosis and treatment among racially and ethnically minoritized individuals.

OBJECTIVE

Understand the factors influencing willingness of Blacks/African Americans to participate in AD biomarker research and identify opportunities to improve enrollment.

METHODS

We enrolled Blacks/African Americans (N = 145) between 46-85 years of age who had previously participated in AD research. Participants gave open-ended responses to a vignette describing a hypothetical biomarker research study. Using qualitative content analysis, we identified themes that motivated and discouraged enrollment in AD biomarker research.

RESULTS

Participant responses were categorized into several themes. Themes motivating participation included a desire to know their biomarker results and to support research. Major themes discouraging participation included concerns about potential negative psychological outcomes to learning one's increased risk for AD, doubt about the usefulness of testing, and worry about the potential physical harms of testing.

CONCLUSION

Understanding themes motivating and discouraging AD preclinical biomarker research participation may inform research material development, approach to community engagement, and/or trial design to increase enrollment of Blacks/African Americans.

Retaining Participants in Longitudinal Studies of Alzheimer's Disease

BACKGROUND

Retention of study participants is essential to advancing Alzheimer's disease (AD) research and developing therapeutic interventions. However, recent multi-year AD studies have lost 10% to 54% of participants.

OBJECTIVE

We surveyed a random sample of 443 participants (Clinical Dementia Rating [CDR]≤1) at four Alzheimer Disease Research Centers to elucidate perceived facilitators and barriers to continued participation in longitudinal AD research.

METHODS

Reasons for participation were characterized with factor analysis. Effects of perceived fulfillment of one's own goals and complaints on attendance and likelihood of dropout were estimated with logistic regression models. Open-ended responses suggesting study improvements were analyzed with a Latent Dirichlet Allocation topic model.

RESULTS

Factor analyses revealed two categories, personal benefit and altruism, as drivers of continued participation. Participants with cognitive impairment (CDR > 0) emphasized personal benefits more than societal benefits. Participants with higher trust in medical researchers were more likely to emphasize broader social benefits. A minority endorsed any complaints. Higher perceived fulfillment of one's own goals and fewer complaints were related to higher attendance and lower likelihood of dropout. Facilitators included access to medical center support and/or future treatment, learning about AD and memory concerns, and enjoying time with staff. Participants' suggestions emphasized more feedback about individual test results and AD research.

CONCLUSION

The results confirmed previously identified facilitators and barriers. Two new areas, improved communication about individual test results and greater feedback about AD research, emerged as the primary factors to improve participation.

Neuropathological and Clinical Correlates of Lewy Body Disease Survival by Race and Ethnicity in the National Alzheimer's Coordinating Center

BACKGROUND

Survival and associated clinical and pathological characteristics in Lewy body disease (LBD)-related dementias are understudied. Available studies focus primarily on white non-Hispanic samples.

OBJECTIVE

We investigated demographic, clinical, and pathological correlates of survival by race and ethnicity in an autopsy-confirmed cohort of LBD cases.

METHODS

Using National Alzheimer's Coordinating Center data, we selected participants who self-identified as Black, Hispanic, or white who had neuropathological assessments showing transitional or diffuse LBD pathology. We used Kruskal-Wallis and Pearson χ2 analyses to investigate group differences in demographic and presenting clinical and pathological characteristics. We used linear regressions to identify predictors of survival with sex, age at symptom onset, education, ethnoracial status, LBD pathology type, and Braak tangle stage included in the model.

RESULTS

Data from 1,441 white, 60 Black, and 54 Hispanic participants were available for analysis. Hispanics were more likely to have transitional LBD pathology and had a longer survival than white and Black participants. After controlling for demographic and pathological variables, length of survival did not differ between Hispanics and Black or white participants. Additional key findings demonstrated discrepancies between clinical diagnoses received at last visit and pathological findings, particularly among Black participants.

CONCLUSION

LBD survival differences by race and ethnicity can be accounted for by LBD pathology type and co-occurring Alzheimer's disease pathology. The discrepancies between clinical diagnoses and pathological findings raise the concern that dementia with Lewy bodies is underdiagnosed in NACC, especially for Black older adults.

Spillover: The Approval of New Medications for Alzheimer's Disease Dementia Will Impact Biomarker Disclosure Among Asymptomatic Research Participants

In this article we address how the recent, and anticipated upcoming, FDA approvals of novel anti-amyloid medications to treat individuals with mild Alzheimer's disease (AD) dementia could impact disclosure of biomarker results among asymptomatic research participants. Currently, research is typically the context where an asymptomatic individual may have the option to learn their amyloid biomarker status. Asymptomatic research participants who learn their amyloid status may have questions regarding the meaning of this result and the implications for accessing a potential intervention. After outlining our rationale, we provide examples of how current educational materials used in research convey messages regarding amyloid positivity and the availability of treatments, or lack thereof. We suggest language to improve messaging, as well as strengths of current materials, in addressing these issues for research participants. Although novel medications are currently only approved for use among symptomatic individuals, their availability may have implications for disclosure among asymptomatic research participants with evidence of amyloid deposition, who may be especially interested in information on these interventions for potential prevention, or future treatment, of mild cognitive impairment or dementia due to AD.

Alzheimer's disease biomarkers in Black and non-Hispanic White cohorts: A contextualized review of the evidence

Black Americans are disproportionately affected by dementia. To expand our understanding of mechanisms of this disparity, we look to Alzheimer's disease (AD) biomarkers. In this review, we summarize current data, comparing the few studies presenting these findings. Further, we contextualize the data using two influential frameworks: the National Institute on Aging-Alzheimer's Association (NIA-AA) Research Framework and NIA's Health Disparities Research Framework. The NIA-AA Research Framework provides a biological definition of AD that can be measured in vivo. However, current cut-points for determining pathological versus non-pathological status were developed using predominantly White cohorts-a serious limitation. The NIA's Health Disparities Research Framework is used to contextualize findings from studies identifying racial differences in biomarker levels, because studying biomakers in isolation cannot explain or reduce inequities. We offer recommendations to expand study beyond initial reports of racial differences. Specifically, life course experiences associated with racialization and commonly used study enrollment practices may better account for observations than exclusively biological explanations.

Alzheimer disease in African American individuals: increased incidence or not enough data?

Research on racial differences in Alzheimer disease (AD) dementia has increased in recent years. Older African American individuals bear a disproportionate burden of AD and cognitive impairment compared with non-Latino white individuals. Tremendous progress has been made over the past two decades in our understanding of the neurobiological substrates of AD. However, owing to well-documented challenges of study participant recruitment and a persistent lack of biological data in the African American population, knowledge of the drivers of these racial disparities has lagged behind. Therapeutic targets and effective interventions for AD are increasingly sought, but without a better understanding of the disease in African American individuals, any identified treatments and/or cures will evade this rapidly growing at-risk population. In this Perspective, I introduce three key obstacles to progress in understanding racial differences in AD: uncertainty about diagnostic criteria, disparate cross-sectional and longitudinal findings; and a dearth of neuropathological data. I also highlight evidence-informed strategies to move the field forward.

In this Perspective, Barnes introduces three key obstacles to progress in our understanding of racial differences in Alzheimer disease and highlights evidence-informed strategies that can move the field forward.