Designing and implementing the IDEAL Study: A randomized clinical trial of genotype disclosure for late-onset Alzheimer's disease in an urban Latino population.

Introduction: The (IDEAL) Study is a randomized clinical trial investigating the psychosocial, behavioral, and cognitive impacts of apolipoprotein E () genotype disclosure for late-onset Alzheimer's disease (AD) among Latinos.

Methods: We used address-based sampling to recruit English- and Spanish-speaking Latinos aged 40-64 living in northern Manhattan for a community-based Baseline Survey about their knowledge and opinions about AD. Participants eligible for the clinical trial were invited to complete an Introductory Session, including AD and genetics education and informed consent, before undergoing genotyping for . Participants were then randomized to learn their risk of AD by age 85 (range: 21%-55%) based on either Latino ethnicity and family history alone, or the same factors and their genotype. Risk information is provided in a semi-structured genetic counseling session. Psychological impacts, health-related behavioral changes, and cognitive performance are evaluated 6 weeks, 9 months, and 15 months later via surveys and qualitative interviews. To promote cultural competence, study materials were developed by a multidisciplinary team including bilingual and bicultural staff, Latinx content experts, and genetic counselors.

Results: We sent invitations to 91,433 households; 5542 (6.1%) responded, 2120 completed the Baseline Survey (78.5% online; 21.5% via computer-assisted telephone interview), and 2087 were deemed eligible, yielding a response rate of 2.3%. Many participants expressed appreciation for the opportunity to contribute to AD research. We randomized 374 participants for the clinical trial.

Discussion: We describe the study design, recruitment and retention strategies, and interventions employed in the IDEAL Study. Our design provides a framework for future studies using rigorous mixed methods. Our findings may facilitate the development of culturally-sensitive educational materials about AD and genetic testing, as well as genetic counseling protocols, to improve coping and adjustment in response to receiving risk information.

Highlights: The (IDEAL) Study investigates apolipoprotein E () genotype disclosure among Latinos using mixed methods.We recruited adults 40-64 years of age without Alzheimer's disease (AD) for a community-based survey and randomized trial.Trial participants receives AD risk estimates with or without genotypes.Psychosocial, behavioral, and cognitive impacts are assessed over 15 months.Findings may inform AD educational materials and genetic counseling protocols.