What Is the Relationship Between Exercise and Psychiatric Disorders?

Although exercise is thought to be associated with low rates of mental illness, this relationship has not been adequately studied. My colleagues and I therefore analyzed data from the National Epidemiologic Survey on Alcohol and Related Conditions collected between 2001 and 2005 to determine if the nationally recommended amount of vigorous exercise is cross-sectionally associated with lower prevalence and incidence rates, as well as higher remission rates, of various psychiatric disorders.

Nondisabled US adults younger than 65 years old (N = 23,505) were categorized into 3 groups: those who followed the national recommendations and exercised vigorously for at least 20 minutes on 3 or more days a week; those who engaged in some vigorous exercise but less than the recommended amount; and those who engaged in no vigorous exercise. The prevalence, incidence, and remission rates of substance use, anxiety, and depressive and bipolar disorders for each group were compared.

The results were unexpected. Over the preceding 4-year period, individuals who engaged in vigorous exercise were more likely than nonexercisers to develop a psychiatric disorder and less likely to attain remission from one. Bipolar II disorder and alcohol dependence were the disorders most consistently and strongly accounting for these differences, while the only disorder inversely associated with any level of exercise was dysthymia.

In addition to indicating that the relationship between exercise and anxiety/depressive disorders deserves further study, these findings raise the possibility that reward-related vulnerabilities associated with bipolar and substance use disorders—such as increased reward-oriented behavior, risk-taking, impulsivity, and sensation-seeking—may influence the pursuit of natural rewards such as exercise. Physical activity, particularly when vigorous, activates the same neurobiological reward systems that substance use or other rewards do.

Although these data suggest that a vulnerability to certain psychiatric disorders is associated with exercise engagement, they do not provide conclusive information on causality. Thus, it is possible that exercise may still have a therapeutic impact on psychiatric disorders, even among those who have a psychiatrically relevant predisposition toward regular exercise.

Consider, for example, individuals with addiction. Our data suggest that individuals predisposed to alcohol dependence exercise more, perhaps because they have reward-related vulnerabilities that lead to heightened reinforcing effects from exercise. Yet, these heightened reinforcing effects may in part explain why early investigations indicate that exercise-based strategies for addiction—where exercise is intended to displace substance-related behavior—may be effective. In other words, the very same reward-related vulnerabilities that predispose to problematic substance use can be part of the solution.

These intriguing data clearly raise more questions than they answer. Prospective studies will be helpful in clarifying the causal relationship between exercise and mental illness, as the relationship between the two is more complex than previously believed.

Financial disclosure: Dr Dakwar had no relevant personal financial relationships to report.​