Potential biases associated with reported parental history of dementia in the Alzheimer's Disease Research Center cohorts: Implications for secondary data analyses

Background Determinants of reported parental history of dementia among older adult research volunteers, and its relation to participation in brain aging studies, are incompletely understood. Objective We aimed to characterize older adults enrolled in Alzheimer's Disease Research Center (ADRC) cohorts by reported history of parental dementia according to age, APOE ε4 dose, sex, race, Hispanic ethnicity, education, and baseline cognitive status. Methods Data were drawn from the National Alzheimer's Coordinating Center Uniform Data Set (NACC UDS). We included all participants who were age ≥ 65 at their most recent visit (N = 34,154). Participants were classified according to reported parental history of dementia (neither parent, mother only, father only, both parents, and unknown). Multinomial regression was used to estimate the adjusted odds ratios for reported parental history of dementia. Results Dementia in at least one parent was reported by 40% of participants (n = 13,596), 52% (n = 17,881) reported that neither parent had dementia, and 8% (n = 2677) did not know. Participants reporting neither parent had dementia, or reported unknown history, were older, less educated, more likely to be minoritized, and were also most likely to be missing APOE genotype (28% and 37%, respectively) and to be diagnosed with cognitive impairment at baseline (62% and 75%, respectively). Conclusions ADRC participants who report no parental dementia history may represent a meaningfully different group of volunteers, and within this group there is also substantial heterogeneity among all of the characteristics of interest investigated, especially by race. These differences need to be carefully considered during secondary analyses of NACC UDS data.