Rivalry or Solidarity: Influence of Siblings in Childhood on Cognitive Function and Cognitive Decline in Later Life

Health disparities in cognition at older ages may be caused by cumulative disadvantages from
childhood, including the family structure in siblings. This paper draws on attachment and
confluence theory to develop hypotheses that I test with data from the Health and Retirement
Study linked to the 1940 U.S. Census. Using latent growth curve models with entropy
balancing weights by the childhood family and contextual covariates, I estimate the long-term
causal influence of sibship. A fully-adjusted model shows that having co-residing siblings in
childhood is associated with faster rates of cognitive decline in late adulthood. The results
also show heterogeneities by the sibling gender composition, with the brother-brother
siblings have worse cognitive function in later life, whereas female siblings face steeper
cognitive decline. The paper suggests that resource dilution between siblings may be a
cumulative risk factor for cognitive aging.