Activity and subsequent depression levels: a causal analysis of behavioural activation group treatment with weekly assessments over 8 weeks.

Research on behavioural activation (BA) for depression assumes that increasing the rate of rewarding activities leads to reduced depressive mood. Although the efficacy of BA treatment has been convincingly demonstrated, assumptions referring to the mechanisms underlying this effect have not been tested decisively yet. The Behavioural Activation Scale for Depression and the Beck Depression Inventory II were administered over 8 weeks in 161 reliably diagnosed patients with unipolar depression who underwent BA treatment in groups.