Are early increases in physical activity a behavioral marker for successful antidepressant treatment?

The aim of this study was to examine whether changes in physical activity predicted reductions in depression during the 8 weeks of antidepressant treatment with vortioxetine.

One hundred individuals were recruited for the (THINC-it ®)-sensitivity to change study. Self-reported moderate-to-vigorous physical activity (MVPA) and depression severity were assessed at baseline, week 4 and week 8. Linear mixed model analyses were performed to examine whether increases in MVPA were associated with reduction in depression severity over the course of treatment and hierarchical logistic regression analyses were performed to assess whether treatment response (responders vs. non-responders) at week 8 was predicted by early change in physical activity (MVPA at week 4), after controlling for individuals' demographics (sex, age, race, education level, BMI) and baseline MVPA and depression severity.

After controlling for individuals' demographics, a significant increase in MVPA predicted reduction in depression severity, β = -2.06, 95% CI -3.18, -0.94, p <0.001. Individuals with more physical activity at week 4 relative to baseline had higher odds of treatment response at endpoint, OR 1.97, 95% CI 1.11 - 3.48, p <0.05. Twenty-one percent of total variance of depression severity was explained by change in MVPA.

The study suggests that early increases in physical activity may be a behavioral marker of antidepressant treatment response. The inclusion of physical activity measures in future clinical treatment trials of depression is recommended to explore whether changes in physical activity mediate or moderate reductions in depression severity associated with the primary treatment.