Mechanisms of change in an Internet-Based ACT study for depression in China

Numerous studies have evidenced the efficacy of Internet-Based Acceptance and Commitment Therapy (iACT). However, few studies have explored the underlying mechanisms through which iACT influences outcomes. This study tested two proposed mechanisms, namely psychological flexibility and cognitive changes in an iACT intervention targeting depression. Chinese university students with at least mild depressive symptoms were randomly assigned to either an iACT group (n = 63) or wait-list control group (n = 61). The iACT intervention consisted of six weekly 30-min units. Self-reported outcomes (depression and positive mental health) and proposed mediators (psychological flexibility and cognitive changes) were assessed pre-intervention, mid-intervention, post-intervention and at 3-month follow-up. Latent growth curve modeling (LGCM) was used to test mediation. Both psychological flexibility and dysfunctional attitudes significantly mediated the associations between iACT and both depressive symptoms and positive mental health. Cognitive defusion only mediated the association between iACT and depressive symptoms. This is the first study to explore the mechanisms of iACT for depression in China. The results have implications for the mechanisms of iACT's effects.