Characterising the covariance pattern between lifestyle factors and structural brain measures: a multivariable replication study of two independent ageing cohorts

Modifiable lifestyle factors have been shown to promote healthy brain aging. However, studies have typically focused on a single factor at a time. Given that lifestyle factors do not occur in isolation, multivariable analyses may provide a more realistic model of the lifestyle-brain relationship. Here, canonical correlation analysis (CCA) was applied to examine the relationship between nine lifestyle factors and seven MRI-derived indices of brain structure. The resulting covariance pattern was further explored with Bayesian regressions. CCA analyses were first conducted on a Danish cohort of older adults (n=251) and then replicated in a British cohort (n=668). In both cohorts, the latent lifestyle factors were positively associated with the latent structural brain measures (UK: r =0.37, p < 0.001; Denmark: r =0.27, p < 0.001). In the cross-validation study, the correlation between lifestyle-brain latent factors was r =0.10, p = 0.008. However, the pattern of associations differed between datasets. Taken together, these findings suggest that baseline characterization and tailoring toward the study sample may be beneficial for achieving targeted lifestyle interventions.