Characterising the covariance pattern between lifestyle factors and structural brain measures: a multivariable study of two cohorts of older adults

AbstractBackgroundModifiable risk factors have been shown to promote healthy brain ageing. However, most studies to date have focused on the relationship between a single risk factor and brain health. Given that risk factors do not occur in isolation, multivariable analyses may provide a more realistic model of the effects of modifiable lifestyle factors on brain ageing.MethodHere, the relationship between 9 modifiable lifestyle factors and 7 indices of brain structure were examined using canonical correlation analyses to identify a covariance pattern between lifestyle factors associated with dementia risk and MRI‐derived measures of brain structure. Analyses were first conducted on a Danish cohort of older adults (n = 251) and then cross‐validated in an independent cohort of older adults from the United Kingdom (n = 668).ResultsIn a 5‐fold cross‐validation analysis of the test dataset, a canonical correlation of 0.14 was observed between the lifestyle and brain variates. In the cross‐study validation, the lifestyle‐brain correlation was r = .10. In the Danish cohort, feelings of loneliness, BMI, depressive symptoms, and years of smoking were the primary contributors to the lifestyle variate (rs ≥ 0.3). In the British cohort, a different pattern of lifestyle factors was found to relate to brain structure the most (rs ≥ 0.3: physical activity, education, alcohol consumption, blood pressure and BMI).ConclusionIn both cohorts, we found that a latent of lifestyle factors was positively associated with age‐related measures of brain structure and this relationship was validated across cohorts of older adults. However, the covariance pattern between lifestyle and brain outcomes differed between datasets. Taken together, these findings highlight how future lifestyle interventions should be tailored to suit their target populations.