Trajectories of Change in a Group Behavioral Activation Treatment for Severe, Recurrent Depression.

Depression is a common and costly problem. Behavioral Activation (BA) is an effective treatment for depression when delivered 1:1, but group treatments often do not perform as well as 1:1 treatments. One way to begin to understand how group treatments perform is to assess the process of change during treatment. This study examined trajectories of change across 10-session group BA for individuals with severe, chronic, or recurrent forms of depression. We also tested whether individuals who had associated sudden gains or depression spikes had better outcomes than those who did not have these change patterns. We examined psychological and sociodemographic predictors of the patterns of change. Participants were 104 individuals who met diagnostic criteria for major depressive disorder and participated in one of 10 BA groups, provided over a 2-year period. A linear, but not quadratic or cubic, rate of change fit the data and the effect size for the change in mood symptoms from baseline to posttreatment was large, Cohen's d = 1.25. Although 34% (26 of the 77 who provided outcome data) of individuals had a sudden gain and 10% (7/77) had a depression spike, neither sudden gains nor depression spikes predicted posttreatment outcomes. None of the demographic or psychological factors (rumination, behavioral activation) predicted the pattern of change. These results suggest that although group BA may help to reduce depressive symptoms in individuals with severe, recurrent, and/or chronic forms of depression, the overall linear pattern of change is different from quadratic patterns of change reported for 1:1 BA.