Predictors of who Serves as an Alzheimer's Disease Research Participant's Study Partner and the Impact of their Relationship on Study Partners' Reports on Participants.

Background: Alzheimer's disease and Alzheimer's disease related dementias (AD/ADRD) research typically requires participants to enroll with a "study partner" (SP). Little is known about what predicts who steps into the SP role or whether the SP's relationship to the participant affects their reports of disease severity.Methods: Health and Retirement Study data (HRS), collected prior to the Aging, Demographics and Memory Study (ADAMS), was used to identify sociocultural factors that predict who serves as a SP in ADAMS. SP-reported outcomes were compared between three types of participant-SP relationships: spousal, adult child, and other.Results: Spouses (35%) and adult children (39%) were similarly likely to serve as SPs. Factors predicting who served differed. In multivariable analyses, adult children rated participants less impaired than spouses on measures of memory, judgment, and organizational abilities (p < .05). Conclusions: The participant-SP relationship has independent effects on the SP's reports of the severity of cognitive impairments.