Engagement in cognitive activity (CA) and physical activity (PA) during the lifespan may counteract brain atrophy later in life. Here, we investigated engagement in CA and PA during late adulthood in association with gray matter volume (GM) in normal older adults, with special focus on the hippocampus. Forty-five cognitively normal older individuals (mean age: 72) underwent T1-weighted MRI and self-reported CA and PA assessment. Whole brain voxel-wise multiple regression models were carried out to assess the relationships between CA, PA and GM volume adjusted by age and sex. Further adjustment for years of education and risk factors were performed. Voxel-wise analyses were projected on 3D hippocampal surface views. Cognitive activity and PA demonstrated independent regional associations with GM after adjustment for confounders. Cognitive activity was related to greater GM in extended brain areas including frontal, temporal and parietal cortices, while PA was associated with increased GM in the prefrontal, insular and motor cortices. Regression maps projected on the hippocampal surface showed a common association of PA and CA within the anterior part of the hippocampus, although the effect of CA was more subtle and also extended to the posterior part. Engagement in PA and CA in late adulthood were independently related to regional GM volume, notably in aging and AD vulnerable areas. These results support the idea that both PA and CA- based interventions may be suitable to promote brain health in late adulthood. The potential synergistic effects of PA and CA need to be addressed in future studies including larger samples.
Keywords: Cognitive activity; Gray matter volume; Hippocampus; Late adulthood; MRI; Physical activity.