Risk of depression after new-onset dementia or cognitive impairment: the Health and Retirement Study.

Background and Objectives: The risk of depression following newly occurred dementia has not been well studied, particularly in diverse populations. This study aimed to estimate the relative risk of depression after newly occurred dementia or cognitive impairment in a cohort of adults aged ≥50 years. Research Design and Methods: Participants from the Health and Retirement Study with and without newly occurred dementia or cognitive impairment, and free of depression at baseline, were included. Dementia and cognitive impairment were ascertained using the Langa-Weir Classification of cognition, and depression was defined as ≥3 symptoms on the 8-item Center for Epidemiologic Studies Depression Scale. Pooled logistic regression with inverse probability weighting was used to estimate the cumulative incidence of depression following newly occurred dementia and cognitive impairment for up to 10 years. Risk ratios (RRs) with 95% confidence intervals (CIs) were obtained using 1,000 bootstrap samples. Subgroup analyses were conducted by age, sex, and race/ethnicity. Results: Risk of depression was significantly elevated after 2 years in those with newly occurred dementia (RR = 1.62, 95% CI: 1.17-2.03) or newly occurred cognitive impairment (RR = 1.62, 95% CI: 1.45-1.79). Elevated risks persisted throughout the 10-year follow-up. These risks were similar in men and women and significantly elevated in most subgroups. Discussion and Implications: Incident dementia and cognitive impairment were associated with immediate and sustained elevated risk of depression across 10 years of follow-up. These findings highlight the importance of prevention strategies and timely screening for depression in people with newly occurred dementia or cognitive impairment.