Physical Activity & CVD Risk

A new study published in the Journal of the American College of Cardiology provides some mechanistic insight into the benefits of physical activity for cardiovascular disease (CVD) risk reduction, helping to explain why some individuals may have larger benefits than others. This study examined records from over 50,000 individuals who completed a survey regarding their level of physical activity and compared it with their risk for developing CVD over a 10-year period. As might be expected, more physical activity was associated with a 20% lower risk for CVD (adjusted).

Interestingly, a subset of nearly 800 of these participants also underwent 18F-fluorodeoxyglucose positron emission tomography/computed tomographic imaging, and stress-related neural activity was defined by the ratio of resting amygdala to cortical metabolic activity (AmygAC). Metabolic activity in the amygdala has previously been well-correlated with markers of psychological/ emotional stress (as well as systemic markers of inflammation), and has also been shown to robustly predict CVD events. This recent study suggested that greater physical activity was linked to a lower AmygAC, and that this reduction partly mediated the decrease in CVD risk. In other words, reducing the stress-related activity in the brain through physical activity was partly responsible for lowering CVD risk. The magnitude of this association was even greater among study participants with pre-existing depression compared to those without depression. A previous study conducted among women with obesity found that not only were their levels of stress-associated metabolic activity in the amygdala higher, but physical activity helped to normalize this elevation, and abolished its association with systemic inflammation. This new study adds to our understanding of the potential mechanisms that underlie physical activity.