Fig. 2: Major lifestyle events are reflected in longitudinal progression of structural whole-brain asymmetry patterns.

A Two measures of structural brain asymmetry change both showcase relevant longitudinal progression. The amount of asymmetry change (MBAC) captures how much the structural imbalance between hemispheres progressed, regardless of direction. Asymmetry change (LBAC) captures how structural imbalance between hemispheres progresses, including which hemisphere showcases greater change. Mean LBAC and MBAC across all 33 statistically robust asymmetry patterns are shown. Error bars represent the standard error of the mean. All asymmetry patterns concurrently consider brain features spanning cortical and subcortical grey matter, major white matter tracts, and cerebellar grey and white matter. All LBACs were compared in terms of relative right versus left grey matter cortical change to aid in interpretation. This composite reference measure tracks aggregate cortical asymmetry change but does not reflect the hemispheric bias of any individual grey matter homologue, or the hemispheric biases of cerebellum or white matter tracts. B, C The (Cohen’s d) effect of retirement status across multiple separate patterns is larger than the (Cohen’s d) effect of the pattern with the largest sex effect. Cohen’s d effect size of LBACs between sex or employment contrasts. Three employment Cohen’s d contrasts were conducted per asymmetry pattern, comparing participants who were in full-time employment at both time points (employed), in retirement at both time points (retired) or transitioned from full-time employment at the first imaging visit to retired at the second imaging visit (retiring). Grey rectangle indicates the single largest absolute Cohen’s d for sex-contrast (pattern 21, |d | = 0.176). Source data are provided as a Source Data file.