O4‐07‐06: NEIGHBORHOOD DISADVANTAGE PREDICTS HIPPOCAMPAL VOLUME AMONG PARTICIPANTS IN THE WISCONSIN REGISTRY FOR ALZHEIMER'S PREVENTION

Individual-level factors such as age, APOEɛ4 genotype and parental history of Alzheimer's disease (AD) are well-known predictors of AD, but the impact of neighborhood socioeconomic disadvantage is less well established. In other diseases, like diabetes, neighborhood disadvantage impacts risk independently of and sometimes more strongly than individual factors. The Area Deprivation Index (ADI) is a measure of neighborhood disadvantage using housing, employment, education and poverty metrics at the census block-group level drawn from the US American Community Survey. In previous studies, ADI has been associated with multiple health-related outcomes, and we have previously observed that higher ADI (a more disadvantaged neighborhood) is associated with worse performance on hippocampal-dependent memory tasks in our study population. However, the relationship between neighborhood disadvantage and AD-associated changes in brain morphometry remains unknown. Participants (N=429) were older-middle aged adults enrolled in the Wisconsin Registry for Alzheimer's Prevention study who had undergone a structural T1-weighted MRI scan. Participants were ranked by ADI, with those in the most highly disadvantaged 10% of neighborhoods compared to all others from less disadvantaged neighborhoods. Morphometric volume data of sub-cortical brain regions were obtained using FSL FIRST. Multiple linear regression was used for statistical analyses. Living within a highly disadvantaged neighborhood was associated with decreased hippocampal volume controlling for total intracranial volume, age, parental history of AD, APOE ɛ4 genotype, sex, MRI scanner and head coil (β= -375.21, p<.05). These findings suggest that living within a highly disadvantaged neighborhood impacts hippocampal volume. While the factors underlying this effect are unknown, chronic stress has been shown to lead to hippocampal volume loss and represents a possible mechanism by which neighborhood disadvantage could lead to the observed findings. Given that the hippocampus is affected early in AD, it is possible that neighborhood-level factors may exacerbate pathological brain morphometry changes in AD. Further study is needed to determine the impact of ADI on AD risk, and the potential for ADI to identify at-risk populations for AD prevention and early intervention efforts.