Effectiveness of Single-Session Acceptance and Commitment Therapy for Generalized Anxiety Symptoms.

Design: Single-group, quasi-experimental, repeated-measures study. All participants received the same intervention. There was no randomization and no control or comparison group. Participants: Fifty full-time undergraduate students aged 18 to 25 years at GIFT University, Gujranwala (25 male, 25 female), recruited through purposive sampling. Eligibility required a GAD-7 score of 5 or above and a primary diagnosis of generalized anxiety disorder confirmed by the SCID-5. Exclusion criteria: current psychotherapy or pharmacological treatment for anxiety; a self-reported history of severe psychiatric disorder (e.g., psychotic disorder or bipolar disorder) or any condition judged likely to interfere with participation; inability to give informed consent or complete the procedures independently. Sample size was calculated in advance with G\*Power 3.1.9.7 (repeated-measures ANOVA, three measurements, f = 0.25, alpha = .05, power = .80), giving a minimum of 43 participants. Intervention: One 120-minute, therapist-led, individual, face-to-face SS-ACT session in Urdu, delivered by the researcher. It had seven stages covering all six core ACT processes: introduction and psychoeducation (15 min), present-moment awareness (15 min), cognitive defusion (20 min), acceptance (20 min), self-as-context (15 min), values clarification (15 min) and committed action (20 min). Procedure: Phase 1, GAD-7 screening of consenting undergraduate students. Phase 2, SCID-5 diagnostic confirmation. Phase 3, pre-intervention measures, the SS-ACT session, post-intervention measures immediately afterwards, and a two-week follow-up. Measures: GAD-7 (primary outcome) at pre-intervention (T1), immediately post-intervention (T2) and two-week follow-up (T3). AAQ-II (psychological inflexibility, process variable) at T1 and T2 only. Objectives: (1) to investigate the baseline level of GAD symptoms using the GAD-7; (2) to evaluate the effectiveness of SS-ACT in reducing GAD symptoms; (3) to investigate gender differences in GAD symptom reduction following SS-ACT; (4) to examine change in psychological inflexibility (AAQ-II) from pre- to post-intervention. Statistical analysis: Repeated-measures ANOVA for GAD-7 across three time points, with the Greenhouse-Geisser correction where sphericity was violated; Bonferroni-adjusted pairwise comparisons; mixed-design ANOVA for the Time x Gender interaction; repeated-measures analysis of AAQ-II from pre- to post-intervention. Effect sizes: Cohen's d for pairwise comparisons and partial eta-squared for omnibus effects. Alpha = .05.