Social Health Is Associated With Structural Brain Changes in Older Adults: The Rotterdam Study.

Background: Social health markers have been linked to the development of dementia. We hypothesize that social health affects brain structure and consequently influences cognitive function. We aim to elucidate the cross-sectional and longitudinal associations between social health markers and structural brain changes in older adults in the general population.

Methods: Social health markers (loneliness, perceived social support, marital status) were assessed in the Rotterdam Study from 2002 to 2008. Magnetic resonance imaging of the brain was performed repeatedly between 2005 and 2015 for 3737 participants to obtain brain volumetrics, cerebral small vessel disease markers, and white matter microstructural integrity as measures of brain structure. Cross-sectional associations between social health and brain structure were studied using multivariable linear and logistic regression models. Longitudinal associations between baseline social health and changes in brain structure were examined using linear mixed models and generalized estimating equations.

Results: Loneliness was associated with smaller white matter volume at baseline (mean difference = -4.63 mL, 95% CI = -8.46 to -0.81). Better perceived social support was associated with larger total brain volume and gray matter volume at baseline and a less steep decrease in total brain volume over time. Better social support was associated with higher global fractional anisotropy and lower mean diffusivity at baseline. Participants who had never been married had a smaller total brain volume (mean difference = -8.27 mL, 95% CI = -13.16 to -3.39) at baseline than married peers.

Conclusions: Social health is associated with brain structure. Better perceived social support at baseline was associated with better brain structure over time.