A Comparison of the Effectiveness of Hypnotherapy and Acceptance and Commitment Therapy (ACT) on Working Memory in Patients with Fibromyalgia in Tehran

The present study aimed to compare the effectiveness of Acceptance and Commitment Therapy (ACT) and hypnotherapy on working memory performance—specifically response accuracy and reaction time—in patients with fibromyalgia in Tehran. This semi-experimental study employed a randomized pretest-posttest-follow-up design with a control group. Forty-five patients diagnosed with fibromyalgia based on rheumatologic and orthopedic evaluations were selected via convenience sampling from clinics and hospitals in Tehran. Participants were randomly assigned into three groups: ACT (n = 15), hypnotherapy (n = 15), and control (n = 15). The ACT intervention was delivered based on a validated 8-session protocol, and hypnotherapy followed a structured 10-session clinical hypnosis model. The control group received standard pharmacological treatment without psychological intervention. Working memory was assessed using the N-Back task at three stages: pretest, posttest, and three-month follow-up. Data were analyzed using repeated measures ANOVA, Bonferroni post hoc tests, and MANCOVA. Both ACT and hypnotherapy groups showed significant improvements in working memory response accuracy and reaction time from pretest to posttest and follow-up (p < .01), whereas the control group exhibited no sustained improvements. ACT demonstrated significantly greater effects than hypnotherapy and medication at the follow-up stage in both cognitive dimensions (p < .01). Bonferroni comparisons revealed significant differences between ACT and the control group (p < .01), as well as between ACT and hypnotherapy in favor of ACT at follow-up. Hypnotherapy was also significantly more effective than medication in improving working memory (p < .05). The results suggest that both ACT and hypnotherapy are effective interventions for enhancing working memory in patients with fibromyalgia, with ACT showing superior long-term efficacy. These findings support the incorporation of psychological therapies into standard care for cognitive symptom management in fibromyalgia.