Does physical activity mediate the reduction of depressive symptoms in older adults treated with behavioural activation? A secondary analysis of a cluster randomised trial.

BACKGROUND

Behavioural activation reduces depressive symptoms in older adults but its working mechanisms remain unknown. Physical activity may play a role by decreasing depressive symptoms in older adults. We investigated whether an increase in physical activity explains the effects of behavioural activation on depressive symptoms in older adults.

METHODS

Participants were 44 adults aged 65-88 years, who participated in a cluster randomised trial evaluating the effectiveness of an eight-week behavioural activation treatment (n = 25) compared with eight weeks of treatment as usual (TAU; n = 19) in primary care. Mediation analysis was used to evaluate whether the effects of behavioural activation on depression were mediated by physical activity as assessed by trunk accelerometer.

RESULTS

Physical activity did not mediate the effect of behavioural activation on depression because physical activity was not related to type of treatment (p = 0.336). An increase in physical activity was associated (R2adj = 0.075) with a decrease in depressive symptoms, regardless of type of treatment (p < 0.05).

CONCLUSION

In this sample, physical activity did not explain the difference in effectiveness between behavioural activation and treatment as usual. In line with the literature, our results showed an association of a small increase in physical activity with a decrease in depressive symptoms, regardless of treatment modality. Larger studies are needed to replicate these findings.

TRIAL REGISTRATION: Netherlands Trial Register, NL5436.