Larger Lateral Prefrontal Cortex Volume Predicts Better Exercise Adherence Among Older Women: Evidence From Two Exercise Training Studies

BACKGROUND: Recent research has suggested an important role of lateral prefrontal cortex (lPFC) in consistent implementation of positive health behaviors and avoidance of negative health behaviors. METHODS: We examined whether gray matter volume in the lPFC prospectively predicts exercise class attendance among older women (n = 122) who underwent either a 52-week or 26-week exercise training intervention. Structural magnetic resonance imaging determined gray matter volume at baseline. RESULTS: Independent of intracranial volume, age, education, body composition, mobility, depressive symptoms, and general cognitive functioning, larger lPFC volume predicted greater exercise class attendance (all p values < .05). Follow-up whole-brain analyses further confirmed that regions in the lPFC-especially the left middle frontal gyrus (p < .005)-predicted future exercise adherence as well as identified other regions, especially in the insula and temporal cortex, that predicted exercise adherence. CONCLUSIONS: These findings suggest that sustained engagement in exercise training might rely in part on functions of the lPFC and that lPFC volume might be a reasonable proxy for such functions.