Exercise as treatment for depression

Studies have reported that physical activity can be protective against developing depression and that exercise can be as effective as pharmacotherapy or psychotherapy in the treatment of depression. However less is known about the associations of sedentary behavior with depression, the optimal intensity of exercise for treating depression, especially in the long- term and whether prescribing exercise for depression will change the patterns of physical activity and sedentary behavior after the intervention is completed.

Data for this thesis derive from the Regassa study, a randomized controlled trial, which included three exercise groups at different intensity levels and a group that received Treatment As Usual (TAU). The participants were 18-67 years old with mild to moderate depression at baseline. The aim of Study I was to measure how physically active and sedentary people suffering from depression are and the association of physical activity and sedentary behavior with depression severity. Depression severity was measured using the Montgomery-Åsberg Depression Rating Scale (MADRS). Accelerometer data was collected at baseline to assess physical activity and sedentary behavior (N=165). The aim of Study II was to determine the post- treatment (12 weeks) effect of three different exercise intensity groups (light, moderate and vigorous) on depression severity (MADRS) and compare with TAU (N=620). Study III used accelerometer data to determine whether the three exercise groups (N=68) had changed their physical activity and sedentary behavior patterns following the completion of the intervention. Study IV compared long-term effects (12 months) of the three exercise groups and TAU (N=620) on depression severity (MADRS).

The results showed that in this sample of depressed adults a large proportion of time was spent in sedentary pursuits and depression severity was associated with Light Physical Activity (LIPA) and number of sedentary bouts (Study I). Exercise, whether performed at light, moderate or vigorous intensity, was at least comparable with TAU, both in the short term (Study II) and long-term (Study IV) in reducing depression severity. Light intensity exercise was shown to have lower depression severity than TAU, both in the short (Study II) and long-term (Study IV). All exercise groups reduced sedentary and LIPA time though non- significantly following the conclusion of the intervention, but some detrimental effects were seen on sedentary patterns (fewer breaks and longer bouts) in the moderate group and a reduction of MVPA in the light and moderate groups (Study III).

The findings in this thesis show that the treatment potential is high and that exercise can be prescribed for depression at an intensity ranging from light to vigorous. Both short and long- term effects were comparable to TAU. The exercise intervention led to some positive changes in overall physical activity and sedentary behavior. However, some detrimental effects were seen, which could be further explored in future studies including a component for targeting sedentary behavior.

List of scientific papers

I. Helgadottir B, Forsell Y, Ekblom Ö. Physical actitivity patterns of people affected by depressive and anxiety disorders as measured by accelerometers: A cross sectional study. PLoS One. 2015;10(1).
https://doi.org/10.1371/journal.pone.0115894

II. Helgadottir B, Hallgren M, Ekblom Ö, Forsell Y. Training fast or slow? Exercise for depression: A randomized controlled trial. Preventive Medicine. 2016; 8(91):123-131.
https://doi.org/10.1016/j.ypmed.2016.08.011

III. Helgadottir B, Owen N, Dunstan DW, Hallgren M, Ekblom Ö, Forsell Y. Changes in Physical Activity and Sedentary Behavior Associated with an Exercise Intervention in Depressed Adults. [Submitted]

IV. Helgadottir B, Forsell Y, Möller J, Hallgren M, Ekblom Ö. Long-term effects of exercise at different intensity levels on depression. [Manuscript]