Sibling Deaths, Racial/Ethnic Disadvantage, and Dementia in Later Life.

OBJECTIVES: Sibling loss is understudied in the bereavement and health literature. The present study considers whether experiencing the death of siblings in mid-to-late life is associated with subsequent dementia risk and how differential exposure to sibling losses by race/ethnicity may contribute to racial/ethnic disparities in dementia risk.

METHODS: We use discrete-time hazard regression models, a formal mediation test, and a counterfactual simulation to reveal how sibling loss in mid-to-late life affects dementia incidence and whether unequal exposures by race/ethnicity mediate the racial/ethnic disparities in dementia. We analyze data from the Health and Retirement Study (2000-2016). The sample includes 13,589 respondents (10,607 non-Hispanic White, 1,761 non-Hispanic Black, and 1,158 Hispanic adults) aged 65 years and older in 2000 who show no evidence of dementia at baseline.

RESULTS: Discrete-time hazard regression results show that sibling loss in mid-to-late life is associated with up to 54% higher risk for dementia. Sibling loss contributes to Black-White disparities in dementia risk. In addition, a simulation analysis shows that dementia rates would be 14% lower for Black adults if they experienced the lower rates of sibling loss experienced by White adults. This pattern was not observed among Hispanic adults.

DISCUSSION: The death of a sibling in mid-to-late life is a stressor that is associated with increased dementia risk. Black adults are disadvantaged in that they are more likely than Whites to experience the death of siblings, and such losses contribute to the already substantial racial/ethnic disadvantage in dementia.