Racial and Ethnic Representation in Dementia Clinical Trials Registered on ClinicalTrials.gov in the United States, United Kingdom, and Canada

OBJECTIVE: To evaluate racial and ethnic representation and temporal trends in phase II-IV dementia clinical trials conducted in the United States, United Kingdom, and Canada. METHODS: We interrogated ClinicalTrials.gov for interventional dementia and Alzheimer's disease (AD) trials completed since 2000. Data on age, gender, and ethnicity were extracted from 163 eligible trials. Representation was compared across two time periods (2000-2015 and 2016-2019) to assess progress in diversity. RESULTS: Of the 163 trials, 58.9% (n = 96) reported ethnicity data. Among the 12,900 participant records in these trials, 80.6% were Caucasian. Since 2016, despite improved reporting standards (100% of recent trials reported ethnicity), actual diversity declined: Asian participant representation dropped from 4.9% to 1.2%, and Hispanic/Latino representation fell from 2.2% to 0.7%. No ethnic minority group showed an increase in participation over the study period. CONCLUSIONS: Diverse ethnic groups remain significantly underrepresented in dementia clinical trials, with diversity metrics stagnating or declining over the last decade. Greater inclusivity in trial design and recruitment is urgently required to ensure that emerging dementia treatments are safe and effective for all populations.