Life-course socioeconomic conditions and change in hippocampal volume in older adults

Several studies have reported a relationship between socioeconomic conditions and depression and cognitive functioning in late-life. However, the neurobiological pathways underlying this association remain unknown. Reduced hippocampal volume (HcV) has been linked to depression, cognitive decline, and stress.

This study aims to estimate the association between socioeconomic conditions and change in HcV in a prospective community-based cohort of older adults (N=1333, age=65-80 years). Multivariable linear regression models were used to estimate the associations between individual socioeconomic factors and life-course socioeconomic position (SEP) and the annualized percent change in HcV. The factors investigated were maternal and paternal education as indicators of childhood socioeconomic conditions, and subject's education and socio-professional category for adult socioeconomic circumstances. We explored three models of life-course SEP: 1) the cumulative (adding childhood and adulthood factors into a cumulative score); 2) the sensitive-periods (modeling all factors simultaneously); 3) and the social-mobility framework (trajectories from childhood to adulthood).

Subjects whose mothers had high educational attainment have a lower annualized percent change in HcV compared to those whose mothers had no education (coefficient=-0.44; p-value=0.04). This result remained unchanged after adjustment for potential confounders. Change in HcV was not associated with cumulative SEP or social-mobility frameworks. Under the sensitive-periods model, maternal educational level was inversely associated with change in HcV (coefficient=-0.47, p-value=0.04) and a higher subject's professional category was marginally associated with a slower HcV atrophy (coefficient=-0.15, p-value=0.08).

In conclusion, life-course SEP was not associated with HcV changes; there is some indication for a role for maternal education and participant's profession.