Social disorder, APOE-E4 genotype, and change in cognitive function among older adults living in Chicago.

The goal of this paper is to describe the simultaneous influence of social and genetic risk factors on declines in cognitive functioning among older American adults. We use detailed information about the social characteristics of older adults' neighborhoods from the Chicago Health and Aging Project (n = 1655; ages 65+) in conjunction with information about respondent's APOE genotype to predict changes in cognitive function over time. Results indicate that the presence of the ε4 allele is associated with a significantly lower cognitive function score at baseline and greater declines in cognitive function compared to those without this risk allele. Importantly, we also show significant variation in the effect of the ε4 allele across neighborhoods and our results indicate that this genotype is more strongly associated with cognitive function for residents of neighborhoods with the lowest levels of social disorder. Our findings support the non-causal social push gene-environment interaction model.