The Effectiveness of Acceptance and Commitment Therapy (ACT) in patients presenting with Depression in Saudi Arabia

Background: Depression continues to be a serious public mental health issue in Saudi Arabia. Cultural stigma, fewer resources, and reliance on medication limits access to evidence-based psychotherapies. Acceptance and Commitment Therapy (ACT) is a third-wave cognitive-behavioural intervention that promotes the use of mindfulness, psychological flexibility, and values-based living, which has potential for cultural adaptation. This thesis evaluated the efficacy of ACT through a systematic review and meta-analysis of the international literature, and an empirical clinical trial in Saudi Arabia.

Methods: A systematic review and meta-analysis was undertaken in accordance with PRISMA; a comprehensive review of published randomised controlled trials (RCTs) of ACT for depression published from 2019 to 2024 was completed. The researcher also conducted a quantitative experimental study at King Khalid University Hospital. Thirty-four participants diagnosed with depression were randomised into either the ACT intervention group (n=17), or standard care control group (n=17). Psychological indicators of depression (BDI, PHQ-9), anxiety (GAD-7, TMAS), mindfulness (KIMS, MAAS), cognitive fusion (ATQ-F, ATQ-B), and thought suppression (WBSI) were measured three times: pre-intervention (T1), post-intervention (T2), and follow-up (T3). The data were analysed using repeated measure ANOVA, independent t-tests and regression models using SPSS v30.

Results: The meta-analysis found ACT produced moderate levels of statistically significant reductions in depressive symptoms across various populations and delivery models. Additionally, the Saudi clinical trial demonstrated improvements in depression scores for ACT participants, specifically, BDI interventions decreased from 36.06 to 18.88, and PHQ-9 dropped from 17.71 to 8.65, contrasting with negligible change in controls. Improvements were seen in anxiety scores (GAD-7, TMAS) and negative thoughts (ATQ, WBSI), while mindfulness (KIMS, MAAS) was meaningfully better. Time × Group interactions were large and statistically significant, thus supporting ACT intervention versus standard care. Regression analyses showed group assignment was the strongest moderator of outcomes, while gender and age were of lesser importance. Improvements were deemed most beneficial immediately post-treatment and at follow-up, but regression to the mean was suspected on delayed assessments; thus, future booster sessions would be beneficial.

Conclusion: This thesis provides converging findings from international trials, with a Saudi-based experiment that ACT represents an effective intervention that adapts for cultural resonance and acceptance for depression and related distress. ACT improves aspects of mindfulness, cognitive rigidity, and results in sustainable improvements to respondents' mental health. In Saudi Arabia, ACT therapy could be embedded into healthcare service provision through digital and scalable models to close treatment access barriers, reduce stigma, and offer a credible one-step improvement pathway. Long-term maintenance boosters are considered to convert the therapeutic gains to longer-term benefits.