Eligibility Rates among Racially and Ethnically Diverse US Participants in Phase 2 and Phase 3 Placebo-Controlled, Double-Blind, Randomized Trials of Lecanemab and Elenbecestat in Early Alzheimer Disease.

OBJECTIVE: Many factors contribute to inadequate diversity in Alzheimer disease (AD) clinical trials. We evaluated eligibility rates among racial and ethnic groups at US sites in large global multisite trials in early AD. METHODS: Using screening data from 4 randomized, double-blind, placebo-controlled clinical trials in early AD, we assessed rates of eligibility among racial and ethnic groups controlling for other demographic covariates. Each trial incorporated positron emission tomography and/or cerebrospinal fluid to evaluate brain amyloid pathology, as well as typical eligibility criteria used in early AD trials. RESULTS: Across the trials, 10,804 US participants were screened: 193 (2%) were of Hispanic ethnicity and Black race, 2,624 (25%) were of Hispanic ethnicity and White race, 118 (1%) were of non-Hispanic ethnicity (NH) and Asian race, 696 (7%) were of NH ethnicity and Black race, and 7,017 (65%) were of NH ethnicity and White race. Data from 156 participants who did not fit into these categories were excluded. Accounting for age, sex, and trial and using NH White participants as a reference group, we observed higher probabilities of ineligibility for amyloid biomarker criteria among Hispanic Black (odds ratio [OR] = 3.20, 95% confidence interval [CI] = 2.11-4.88), Hispanic White (OR = 4.15, 95% CI = 3.58-4.83), NH Asian (OR = 2.35, 95% CI = 1.23-4.55), and NH Black (OR = 3.75, 95% CI = 2.80-5.06) participants. INTERPRETATION: Differential eligibility may contribute to underrepresentation of some minoritized racial and ethnic groups in early AD trials. Amyloid biomarker eligibility is a requirement to confirm the diagnosis of AD and for treatment with amyloid-lowering drugs and differed among racial and ethnic groups. ANN NEUROL 2024;95:288-298.

Retention of American Indian and Alaska Native participants in the National Alzheimer's Coordinating Center Uniform Data Set.

INTRODUCTION: The number of American Indian and Alaska Native (AI/AN) elders is expected to double by 2060. Thus it is imperative to retain AI/AN participants in longitudinal research studies to identify novel risk factors and potential targets for intervention for Alzheimer's disease and related dementias in these communities. METHODS: The National Alzheimer's Coordinating Center houses uniformly collected longitudinal data from the network of National Institute on Aging (NIA)-funded Alzheimer's Disease Research Centers (ADRCs). We used logistic regression to quantify participant retention at 43 ADRCs, comparing self-identified AI/AN participants to non-Hispanic White (NHW) participants, adjusting for potential confounding factors including baseline diagnosis, age, sex, education, and smoking. RESULTS: The odds of AI/AN participant retention at the first follow-up visit were significantly lower than those for NHW participants (adjusted odds ratio [aOR]: 0.599; 95%: 0.46-0.78; p < 0.001). DISCUSSION: These results suggest the need for improved strategies to retain AI/AN participants, perhaps including improved researcher-community relationships and community engagement and education. HIGHLIGHTS: American Indian and Alaska Native (AI/AN) research participants were retained to the first follow-up appointment at lower rates than non-Hispanic White (NHW) participants. AI/AN participants are retained at lower rates than NHW participants for long-term follow-up. The majority of AI/AN participants were not retained to the second follow-up visit.

Post-disclosure distress among racial and ethnic groups in a preclinical AD trial.

INTRODUCTION: Trialists need a thorough understanding of whether reactions to Alzheimer's disease (AD) biomarker information differ among racial and ethnic groups in preclinical AD trials. METHODS: We used data from the Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease Study to analyze cognitively unimpaired participants' responses on the Impact of Event Scale (IES) 24 to 72 hours after amyloid disclosure. We fit a linear regression model to test whether mean IES scores differed among participants from specific racial and ethnic groups. We considered potential effect modification by amyloid status. RESULTS: Reactions to disclosure did not significantly differ among participant groups based on self-reported race and ethnicity. Although the results were not significant when stratified by amyloid status, all racial and ethnic groups except for participants self-reporting Hispanic/Latino ethnicity were observed to have higher mean IES in the elevated amyloid group. DISCUSSION: These results support continued use of current disclosure methods in preclinical AD trials.

Effect of gamification with a support partner to increase physical activity in older adults at risk for Alzheimer's disease: The STEP 4Life randomized clinical trial.

INTRODUCTION: Physical activity is associated with reduced risk of cognitive and functional decline but scalable, sustainable interventions for populations at risk for Alzheimer's disease (AD) and AD and related dementias (ADRD) are lacking. METHODS: A 12-week randomized-controlled trial was conducted with a 3-week follow-up using a national AD prevention registry (GeneMatch). The control group (n = 50) set step goals and received daily feedback. The intervention group (n = 44) also received a behaviorally designed game based on achieving step goals and reinforced by a support partner. RESULTS: Intervention participants (94 participants, mean age 70, 78% female) had greater change in mean daily step count than control of 1699 steps/day (95% confidence interval [CI], 1149-2249), P < 0.0001, which was sustained in the follow-up period at 1219 steps/day (95% CI, 455-1983), P = 0.0018. Carriers of the apolipoprotein E ε4 gene (high risk) did not perform differently than non-carriers; however, high self-reported risk perception was associated with higher activity. DISCUSSION: A gamified intervention was effective in promoting and sustaining higher physical activity in older adults at genetic risk for AD/ADRD. HIGHLIGHTS: A simple game played with a support partner increased walking in older adults at risk for Alzheimer's disease (AD). The game also increased minutes of moderate-to-vigorous physical activity per day. Perception of lifelong AD risk was associated with increased activity but genetic risk (apolipoprotein E ε4+) was not. TRIAL REGISTRATION: ClinicalTrials.gov: NCT05069155.

Brain Health Registry Study Partner Portal: Novel infrastructure for digital, dyadic data collection.

BACKGROUND: In Alzheimer's disease (AD) research, subjective reports of cognitive and functional decline from participant-study partner dyads is an efficient method of assessing cognitive impairment and clinical progression. METHODS: Demographics and subjective cognitive/functional decline (Everyday Cognition Scale [ECog]) scores from dyads enrolled in the Brain Health Registry (BHR) Study Partner Portal were analyzed. Associations between dyad characteristics and both ECog scores and study engagement were investigated. RESULTS: A total of 10,494 BHR participants (mean age = 66.9 ± 12.16 standard deviations, 67.4% female) have enrolled study partners (mean age = 64.3 ± 14.3 standard deviations, 49.3% female), including 8987 dyads with a participant 55 years of age or older. Older and more educated study partners were more likely to complete tasks and return for follow-up. Twenty-five percent to 27% of older adult participants had self and study partner-report ECog scores indicating a possible cognitive impairment. DISCUSSION: The BHR Study Partner Portal is a unique digital tool for capturing dyadic data, with high impact applications in the clinical neuroscience and AD fields. Highlights The Brain Health Registry (BHR) Study Partner Portal is a novel, digital platform of >10,000 dyads. Collection of dyadic online subjective cognitive and functional data is feasible. The portal has good usability as evidenced by positive study partner feedback. The portal is a potential scalable strategy for cognitive impairment screening in older adults.

Racial and ethnic differences in plasma biomarker eligibility for a preclinical Alzheimer's disease trial.

INTRODUCTION: In trials of amyloid-lowering drugs for Alzheimer's disease (AD), differential eligibility may contribute to under-inclusion of racial and ethnic underrepresented groups. We examined plasma amyloid beta 42/40 and positron emission tomography (PET) amyloid eligibility for the ongoing AHEAD Study preclinical AD program (NCT04468659). METHODS: Univariate logistic regression models were used to examine group differences in plasma and PET amyloid screening eligibility. RESULTS: Of 4905 participants screened at time of analysis, 1724 were plasma eligible to continue in screening: 13.3% Hispanic Black, 24.7% Hispanic White, 20.8% non-Hispanic (NH) Asian, 24.7% NH Black, and 38.9% NH White. Plasma eligibility differed across groups in models controlling for covariates (odds ratio from 1.9 to 4.0 compared to the NH White reference group, P < 0.001). Among plasma eligible participants, PET eligibility did not differ by group. DISCUSSION: These results suggest that prevalence of brain amyloid pathology differed, but that eligibility based on plasma was equally effective across racial and ethnic group members. HIGHLIGHTS: Plasma amyloid eligibility is lower in underrepresented racial and ethnic groups. In plasma eligible adults, positron emission tomography eligibility rates are similar across race and ethnicity. Plasma biomarker tests may be similarly effective across racial and ethnic groups.

Frameworks for estimating causal effects in observational settings: comparing confounder adjustment and instrumental variables.

To estimate causal effects, analysts performing observational studies in health settings utilize several strategies to mitigate bias due to confounding by indication. There are two broad classes of approaches for these purposes: use of confounders and instrumental variables (IVs). Because such approaches are largely characterized by untestable assumptions, analysts must operate under an indefinite paradigm that these methods will work imperfectly. In this tutorial, we formalize a set of general principles and heuristics for estimating causal effects in the two approaches when the assumptions are potentially violated. This crucially requires reframing the process of observational studies as hypothesizing potential scenarios where the estimates from one approach are less inconsistent than the other. While most of our discussion of methodology centers around the linear setting, we touch upon complexities in non-linear settings and flexible procedures such as target minimum loss-based estimation and double machine learning. To demonstrate the application of our principles, we investigate the use of donepezil off-label for mild cognitive impairment. We compare and contrast results from confounder and IV methods, traditional and flexible, within our analysis and to a similar observational study and clinical trial.

Economic hardships of Korean American family caregivers of persons with dementia: a mixed-methods study.

Objectives. This study examined the relationships between economic hardships (i.e. perceived financial hardship and job interference) and caregiver burden among Korean American family caregivers of persons with dementia and explored their lived experience caring for their loved ones.Methods. Using a mixed-methods research design, we first conducted a survey with 36 Korean American family caregivers. We also conducted semi-structured, in-depth, individual interviews (n = 33) and subsequently compared the results.Results. Cohabiting with their loved ones, the total duration of caregiving, and financial hardship were statistically significant predictors of higher levels of caregiver burden. Our thematic analysis resulted in four themes: (1) financial hardship, (2) early retirement, (3) dual responsibilities contributing to physical and emotional challenges, and (4) a lack of caregiver support.Conclusion. Our findings suggest the importance of developing culturally appropriate interventions that are affordable and accessible to Korean American family caregivers of persons with dementia.

The Collaborative Approach for Asian Americans and Pacific Islanders Research and Education (CARE): A recruitment registry for Alzheimer's disease and related dementias, aging, and caregiver-related research.

INTRODUCTION: Clinical research focused on aging, Alzheimer's disease and related dementias (ADRD), and caregiving often does not recruit Asian Americans and Pacific Islanders (AAPIs). METHODS: With funding from the National Institute on Aging, we designed and launched the Collaborative Approach for AAPIs Research and Education (CARE), a research recruitment registry to increase AAPIs' participation in ADRD, aging, and caregiving research. We present the design of this novel recruitment program. RESULTS: CARE uses community-based participatory research methods that are culturally and linguistically appropriate. Since CARE's launch, it has enrolled >7000 AAPIs in a 1-year period. The majority enrolled in CARE via community organizations and reported never having participated in any kind of research before. CARE also engages researchers by establishing a recruitment referral request protocol. DISCUSSION: CARE provides a promising venue to foster meaningful inclusion of AAPIs who are under-represented in aging and dementia-related research.

Biomarker disclosure protocols in prodromal Alzheimer's disease clinical trials.

INTRODUCTION: The development of biomarkers for Alzheimer's disease (AD) has allowed researchers to increase sample homogeneity and test candidate treatments earlier in the disease. The integration of biomarker "screening" criteria should be met with a parallel implementation of standardized methods to disclose biomarker testing results to research participants; however, the extent to which protocolized disclosure occurs in trials is unknown. METHODS: We reviewed the literature to identify prodromal AD trials published in the past 10 years. From these, we quantified the frequency of biomarker disclosure reporting and the depth of descriptions provided. RESULTS: Of 30 published trials using positron emission tomography or cerebrospinal fluid-based amyloid positivity as an eligibility criterion, only one mentioned disclosure, with no details on methods. DISCUSSION: Possible reasons for and implications of this information gap are discussed. Recommendations are provided for trialists considering biomarker screening as part of intervention trials focused on prodromal AD. HIGHLIGHTS: Few prodromal Alzheimer's disease (AD) trial papers discuss biomarker disclosure. Disclosure has implications for participants, family members, and trial success. Disclosure must be consistently integrated and reported in prodromal AD trials. Best practice guidelines and training resources for disclosure are needed.

Asian Americans' and Pacific Islanders' preferences in recruitment strategies and messaging for participation in the CARE registry: A discrete choice experiment.

INTRODUCTION: This discrete choice experiment (DCE) identified Asian American and Pacific Islander (AAPI) adults' preferences for recruitment strategies/messaging to enroll in the Collaborative Approach for AAPI Research and Education (CARE) registry for dementia-related research. METHODS: DCE recruitment strategy/messaging options were developed in English, Chinese, Korean, and Vietnamese. AAPI participants 50 years and older selected (1) who, (2) what, and (3) how they would prefer hearing about CARE. Analyses utilized conditional logistic regression. RESULTS: Participants self-identified as Asian Indian, Chinese, Filipino, Japanese, Korean, Samoan, or Vietnamese (N = 356). Overall, they preferred learning about CARE from the healthcare community (vs. community champions and faith-based organizations), joining CARE to advance research (vs. personal experiences), and hearing about CARE through social media/instant messaging (vs. flyer or workshop/seminar). Preferences varied by age, ethnic identity, and survey completion language. DISCUSSION: DCE findings may inform tailoring recruitment strategies/messaging to engage diverse AAPI in an aging-focused research registry.

Dyadic Enrollment in a Phase 3 Mild Cognitive Impairment Clinical Trial.

BACKGROUND: Dyadic enrollment of a participant and study partner is required in mild cognitive impairment (MCI) clinical trials, despite participants being functionally independent. Research examining how the study partner requirement impacts MCI trials remains limited. METHODS: Using the Alzheimer's Disease Cooperative Study donepezil and vitamin E MCI trial data, we quantified the proportions of enrolled spouse, adult child, and other dyads. We used multinomial regression to identify which baseline participant characteristics (age, sex, race and ethnicity, apolipoprotein E ε4 status, education, residence type) were associated with dyad type. RESULTS: Among 769 randomized dyads, 73% were spousal, 14% adult child, and 13% other dyads. Adjusting for multiple comparisons, underrepresented racial and ethnic background (eg, comparing Hispanic to non-Hispanic White participants: adult child vs. spouse odds ratio = 5.86; 95% confidence interval: 2.09, 16.5; other vs. spouse odds ratio = 4.95; 95% confidence interval: 1.83, 13.4), female sex, age, nonhouse residence, and apolipoprotein E ε4 noncarriage were each associated with a higher odds of having an adult child, as well as an other, study partner at enrollment. DISCUSSION: Increasing participation among nonspousal dyads may facilitate more inclusive and representative MCI trial samples.

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.

Direct Mail Recruitment to a Potential Participant Registry.

Recruitment registries are novel tools to accelerate Alzheimer disease research accrual. Optimal methods to populate such registries remain largely unstudied. We sent postcards with 3 unique taglines (Alzheimer's Prevention Research, brain health research, general research) to 100,000 local residents aged 50 years and older to assess the effectiveness of recruiting to an online recruitment registry by mail. The postcard campaign recruited 273 new registry enrollees (0.27% overall response rate). Neither the response rate nor the demographic characteristics of recruited participants differed by the postcard tagline. These results suggest that direct mail may not be the most cost-effective approach to recruit participants to online registries.

Using Direct-to-Consumer Genetic Testing Results to Accelerate Alzheimer Disease Clinical Trial Recruitment.

INTRODUCTION: The apolipoprotein E (APOE) gene is the strongest known genetic risk factor for sporadic Alzheimer disease (AD). APOE can be used as an enrichment strategy or inclusion criterion for AD prevention trials. Personal genomics companies market direct-to-consumer (DTC) genetic tests, including APOE. We assessed DTC APOE testing usage among enrollees of the University of California Irvine Consent-to-Contact Registry, an online recruitment registry, and attitudes toward using this information in clinical trial recruitment. METHODS: We emailed links to an electronic survey to registry enrollees age 50 years or older. We assessed participants' use of DTC services, willingness to learn APOE status, and willingness to share genetic information. Logistic regression models assessed relationships between DTC testing usage and demographic characteristics, and with willingness to share results to assist trial recruitment. RESULTS: Among 1312 responders (57% response rate), few (7%) had used DTC testing for APOE. Non-Hispanic Asian enrollees were 93% less likely to have used DTC testing, compared with non-Hispanic Whites [95% confidence interval: (0.01, 0.67)]. Willingness to share APOE information for study recruitment was >90% for both users and nonusers. CONCLUSIONS: Matching participants to trials on the basis of DTC APOE information may be an effective way to streamline AD prevention trial recruitment.

On the design of early-phase Alzheimer's disease clinical trials with cerebrospinal fluid tau outcomes.

BACKGROUND/AIMS: The focus of Alzheimer's disease studies has shifted to earlier disease stages, including mild cognitive impairment. Biomarker inclusion criteria are often incorporated into mild cognitive impairment clinical trials to identify individuals with "prodromal Alzheimer's disease" to ensure appropriate drug targets and enrich for participants likely to develop Alzheimer's disease dementia. The use of these eligibility criteria may affect study power. METHODS: We investigated outcome variability and study power in the setting of proof-of-concept prodromal Alzheimer's disease trials that incorporate cerebrospinal fluid levels of total tau (t-tau) and phosphorylated (p-tau) as primary outcomes and how differing biomarker inclusion criteria affect power. We used data from the Alzheimer's Disease Neuroimaging Initiative to model trial scenarios and to estimate the variance and within-subject correlation of total and phosphorylated tau. These estimates were then used to investigate the differences in study power for trials considering these two surrogate outcomes. RESULTS: Patient characteristics were similar for all eligibility criteria. The lowest outcome variance and highest within-subject correlation were obtained when phosphorylated tau was used as an eligibility criterion, compared to amyloid beta or total tau, regardless of whether total tau or phosphorylated tau were used as primary outcomes. Power increased when eligibility criteria were broadened to allow for enrollment of subjects with either low amyloid beta or high phosphorylated tau. CONCLUSION: Specific biomarker inclusion criteria may impact statistical power in trials using total tau or phosphorylated tau as the primary outcome. In concert with other important considerations such as treatment target and population of clinical interest, these results may have implications to the integrity and efficiency of prodromal Alzheimer's disease trial designs.

Research Attitudes Questionnaire scores predict Alzheimer's disease clinical trial dropout.

BACKGROUND: Missing data are a notable problem in Alzheimer's disease clinical trials. One cause of missing data is participant dropout. The Research Attitudes Questionnaire is a 7-item instrument that measures an individual's attitudes toward biomedical research, with higher scores indicating more favorable attitudes. The objective of this study was to describe the performance of the Research Attitudes Questionnaire over time and to examine whether Research Attitudes Questionnaire scores predict study dropout and other participant behaviors that affect trial integrity. METHODS: The Research Attitudes Questionnaire was collected at baseline and weeks 26 and 52 from each member of 119 participant/study partner dyads enrolled in a Phase 2, randomized, double-blind, placebo-controlled mild-to-moderate Alzheimer's disease clinical trial. Within-subject longitudinal analyses examined change in Research Attitudes Questionnaire scores over time in each population. Logistic regression analyses that controlled for trial arm and clustering in trial sites were used to assess whether baseline Research Attitudes Questionnaire scores predicted trial completion, study medication compliance, and enrollment in optional substudies. RESULTS: Participants and study partners endorsed statistically similar ratings on the Research Attitudes Questionnaire that were stable over time. Participants with baseline Research Attitudes Questionnaire scores above 28.5 were 4.7 (95% confidence interval = 1.01 to 21.95) times as likely to complete the trial compared to those with lower scores. Applying the same cutoff, baseline study partner Research Attitudes Questionnaire scores were similarly able to predict study completion (odds ratio = 4.2, 95% confidence interval = 1.71 to 10.32). Using a score cutoff of 27.5, higher participant Research Attitudes Questionnaire scores predicted study medication compliance (odds ratio = 5.85, 95% confidence interval = 1.34 to 25.54). No relationship was observed between Research Attitudes Questionnaire score and participation in optional substudies. CONCLUSION: This brief instrument that measures research attitudes may identify participants at risk for behaviors that cause missing data.

A Preliminary Study of Clinical Trial Enrollment Decisions Among People With Mild Cognitive Impairment and Their Study Partners.

OBJECTIVE: All Alzheimer disease (AD) clinical trials, including those enrolling patients with mild cognitive impairment (MCI), require dyadic participation. The purpose of this study was to elucidate how people with MCI and their study partners decide whether to enroll in clinical trials. METHODS: This was a mixed methods interview study. We interviewed patient participants with a consensus research diagnosis of MCI and their study partners. Interviews examined how dyads decide whether to enroll in a clinical trial and whether AD biomarker testing affects willingness to enroll. RESULTS: Though most MCI patients and study partners would decide in partnership whether to enroll in a clinical trial, agreement was lower among nonspousal, compared with spousal, dyads. Deterrents to enrollment included concerns about patient safety and inconvenience, especially for study partners. Motivators to enrollment included altruism, the desire to contribute to research, hope for patient benefit, and the desire to learn more about the patient's condition. When asked open-ended questions about motivators to enroll in trials, few patients cited access to biomarker testing specifically, though most expressed a desire to undergo biomarker testing when asked directly. CONCLUSION: Spousal and nonspousal MCI dyads may approach clinical trial decisions differently. Future research should investigate how AD biomarker testing affects participants' willingness to enroll in trials.

Which MCI Patients Should be Included in Prodromal Alzheimer Disease Clinical Trials?

BACKGROUND: Prodromal Alzheimer disease (AD) clinical trials enroll patients with mild cognitive impairment (MCI) meeting biomarker criteria, but specific enrollment criteria vary among trials. METHODS: We used data from AD Neuroimaging Initiative (ADNI) MCI participants to assess AD biomarker eligibility, variation in trial outcome measures, and statistical power. RESULTS: Most (65%) participants meet eligibility criteria based on low cerebrospinal fluid amyloid beta (Aß). Relative to trials enrolling exclusively based on low cerebrospinal fluid Aß, trials including participants with a high ratio of phosphorylated tau to Aß would include an additional 15% of participants. Fewer (34% to 62%) participants met criteria for Aß and tau. Differences in clinical and demographic characteristics of modeled trial samples were minimal. Those with low Aß and high tau showed the greatest change over time on outcome measures. CONCLUSIONS: Eligibility rates for prodromal trials vary depending on the specific biomarker criteria, though differences in demographics and the variation associated with outcome measures are minimal. Broadening inclusion criteria beyond amyloid alone may facilitate recruitment but include patients showing slower progression over time. Biomarker criteria selection should be informed by the goal of enrolling individuals most likely to utilize and benefit from the intervention under investigation in a particular setting.