Factors related to cognitive reserve: a comparative analysis of education, occupation, lifestyle, and social network factors based on brain measures

Cognitive reserve (CR) refers to the ability to sustain cognitive performance despite age- and disease-related brain changes, which supports prolonged independent living. Prior research suggests that education, occupational complexity, participation in cognitively engaging and social activities, lifestyle factors, and social connectedness may enhance CR. However, few studies directly compare the relative significance of these factors within the same sample, using magnetic resonance imaging (MRI) based brain markers to measure CR. We also examine whether, and to what extent, relatively proximal factors serve as downstream effects of education within a cumulative (dis)advantage framework.

We analyzed data from 279 MRI visits from 201 older adults enrolled in the Social Networks and Alzheimer's Disease study, diagnosed as cognitively normal or with mild cognitive impairment. CR was assessed as residual global cognition based on MRI-derived brain measures and demographic covariates. Multivariate models estimated standardized effect sizes for each factor, followed by mediation analyses to assess whether they are downstream of education.

As expected, higher educational attainment was significantly associated with greater CR. Among occupational measures, only complexity with people showed a significant relationship, but this association diminished in fully adjusted models. Cognitive-oriented activities and social network bridging capital were independently associated with CR, while only bridging capital remained significant in fully adjusted models and mediated ∼11% of the association between education and CR.

While early-life education appears fundamental to CR, broader and more diverse social networks are beneficial, partly reflecting downstream effects of education, and may represent a modifiable pathway to promote CR.