Brain structure in the cingulate cortex and locus coeruleus in late life is associated with engagement in complex mental activities across the life span.

There is great interest in characterizing the activities or lifestyle factors that are important for successful aging; nevertheless, rigorous investigations using multimodal neuroimaging measures in conjunction with validated measures of activities are underrepresented in the literature. To address this gap, we assessed whether engagement in complex mental activities across early, middle, and late life, is associated with metrics of brain health in a sample of cognitively unimpaired older adults (N = 76). Complex mental activities were measured using a validated questionnaire indexing lifetime engagement in various pursuits (e.g., occupational complexity, stimulating activities). Indices of late life brain health were quantified using simultaneous PET-MRI, which included estimates of gray matter volume, cortical thickness, and tau burden. The integrity of the locus coeruleus (LC) was also assessed in a subsample of participants (N = 60) using MRI. We found that overall higher levels of complex mental activities were associated with larger estimates of gray matter volume and cortical thickness in the cingulate cortex and higher integrity of the LC. There were no associations between complex mental activities and tau burden. Exploratory analyses suggest that the associations between complex mental activities and late life brain health are life stage specific. Greater engagement in complex mental activities in early life was associated with cingulate cortex volumes and thickness, whereas greater levels of complex mental activities in late life were associated with the integrity of the LC. Together, these findings suggest that a mentally stimulating life may help to confer benefits towards brain health in late life.