Objective
The present study tested the efficacy of an unguided internet‐based Acceptance and Commitment Therapy (iACT) program for depression, and identified the psychological characteristics of participants who benefitted the most from the program.
Method
Undergraduate students with mild to severe symptoms of depression were randomized to the iACT group (n = 95) or the waiting‐list group (WLC group; n = 87). Depressive symptoms and positive mental health were assessed at baseline (T0), at the end of the 6‐week program (T1), and at a 3‐month follow‐up (T2).
Results
Compared with the WLC group, the iACT group showed significantly more improvement in depressive symptoms (d = 1.27) and positive mental health (d = 0.59), both at T1 and T2. Latent Profile Analysis identified three classes of participants: Sensitive‐to‐Relationship, Low‐Reactive‐Depression, and Endogenous‐Depression group. In general, the treatment was particularly suitable for the Sensitive‐to‐Relationship class.
Conclusion
The iACT was effective in treating the depressive symptoms of undergraduates, especially suitable for the clients with high baseline depression, high externality, high resistance, and high sensitivity to relationships.