Physical activity as an adjuvant therapy for depression and influence on peripheral inflammatory markers: A randomized clinical trial

Regular exercise is recommended for people with major depressive disorder (MDD) by major treatment guidelines (e.g. the NICE guideline, 2009). In addition, an effect of antidepressant (AD) treatment on pro-inflammatory markers has been reported. However, it remains unclear whether physical activity as an adjuvant to AD treatment increases clinical response rates and is associated with levels of inflammatory markers. A four-week single-blind clinical trial involving forty people with major MDD, divided into an AD group (sertraline) and AD + exercise (40 min/day, four times weekly for four weeks) group was conducted. Peripheral inflammatory markers (IL-12, IL-10, IL-8, IL-6, IL-1β, TNF-α) and cortisol were collected at baseline and at endpoint. We observed a significant decrease in cortisol levels over time, but this change did not differ between the AD and AD + exercise groups. None of the other inflammatory markers showed a significant change in level during the trial. Also, most of the individuals who achieved remission were from the AD + exercise group. Although our study failed to find that the association of physical activity as an adjunct to antidepressants promotes a change in cortisol or interleukins in people with MDD, we found that cortisol seems to be the most sensitive biomarker to antidepressant treatment. Further studies involving larger samples of, longer duration and with other classes of antidepressants and types of exercise should be conducted to better elucidate the link between inflammatory markers and depression.