**4.1. MoodGYM**

One of the most popular and best-studied iCBT programs is MoodGYM. The program comprises an introduction module, five learning modules, and a review module. MoodGYM uses fictional stories built around a set of six cartoon characters to present the principles of CBT in an approachable manner. As the participant progresses through the modules, they learn: (1) how negative thoughts affect their feeling, (2) how to identify those thoughts, (3) how to remove themselves those thoughts to view them objectively, (4) how to reduce stress, and (5) how relationships can affect thoughts and feelings. There are online worksheets, workbooks, and downloadable materials as well as games and activities to complete with each module. Outcome measures are collected before starting and after completing the five modules to determine if MoodGYM improved the participants' symptoms [39].

MoodGYM was developed with the support of the Australian government and is available in five languages. MoodGYM was initially free, but currently this program charges patients \$39 (AUD) for a 12-month subscription to the materials. There are about 850,000 registered users. Recently, a meta-analysis of the effectiveness of MoodGYM for depression and anxiety was performed. For patients with anxiety, MoodGYM had a medium effect size (g = 0.57, 95% CI 0.20, 0.94; I<sup>2</sup> = 85%). For patients with depression or general psychological distress, MoodGYM trended toward effectiveness, but fell short of statistical significance (g = 0.17, 95% CI -0.01, 0.38 and g = 0.34, 95% CI -0.04, 0.68; respectively). Adherence in the included studies ranged widely, from 10–100% of patients completing all modules, though the authors noted that: "adherence rates can be problematic" [39]. The effect size was higher in studies with high adherence (>50% of modules completed) versus those with low adherence (g = 0.64, 95% CI 0.15, 1.14, I<sup>2</sup> = 79% and g = 0.22, 95% CI 0.42, 0.41, I<sup>2</sup> = 72%; respectively).
