Chan KCG, Xia F, Kukull WA. (2025) NACC data: Who is represented over time and across centers, and implications for generalizability. Alzheimer’s & Dementia; 21(9):e70657.  https://doi.org/10.1002/alz.70657

 

INTRODUCTION

Since 2005, the Alzheimer's Disease Research Centers (ADRCs) have recruited participants into the Uniform Data Set (UDS), but enrollment trends and center-level differences remain underexplored. This study investigates temporal patterns and heterogeneity in recruitment across ADRCs, with implications for generalizability.

METHODS

Using data from the National Alzheimer's Coordinating Center (NACC), we assessed trends and between-center variation in baseline characteristics, including age, sex, race, education, clinical diagnosis, referral source, family history, and co-participant relationship.

RESULTS

All characteristics except sex and family history showed directional shifts over time. Substantial between-center heterogeneity was observed in all variables examined.

DISCUSSION

Temporal changes and site-level variability in participant profiles highlight challenges and opportunities for generalizing findings from UDS data. Although not nationally representative, statements about generalization could often be made using UDS data, with strengthened inferences and enhanced transparency through analytic approaches such as sensitivity analysis or meta-analytic techniques treating centers as separate studies.

Highlights