Objective: This study aimed to examine preliminary changes in psychological inflexibility and self-reported aggression following Acceptance and Commitment Therapy (ACT)-based anger management training in patients with bipolar disorder hospitalized in a high-security forensic psychiatric hospital (HSFPH).
Methods: This controlled pilot study included 20 patients diagnosed with bipolar disorder and hospitalized in an HSFPH, with 10 patients assigned to the experimental group and 10 to the control group. The experimental group participated in an eight-session, group-based anger management program incorporating ACT principles, including anger recognition, cognitive defusion, acceptance, values-based behavior, forgiveness, and assertive communication. The Buss-Perry Aggression Questionnaire (BPAQ) and Acceptance and Action Questionnaire-II (AAQ-II) were administered to both groups at baseline and after the intervention.
Results: The experimental group showed significant reductions in BPAQ scores and self-reported aggression following the intervention (Z=-2.8, p<0.05), whereas no significant changes were observed in the control group. Psychological inflexibility, as measured by the AAQ-II, also decreased significantly in the experimental group at posttest (Z=-1.7, p<0.05), whereas no significant change was detected in the control group.
Conclusion: These preliminary findings suggest that ACT-based anger management training may help reduce self-reported aggression and psychological inflexibility in patients with bipolar disorder treated in an HSFPH. Larger studies with longer follow-up periods are needed to determine the durability of these effects and their potential impact on clinically relevant outcomes, including rehospitalization.