This randomized controlled trial aims to evaluate the effect of Acceptance and Commitment Therapy (ACT)-based nursing interventions on social cognition, emotion regulation, and psychological flexibility in individuals diagnosed with schizophrenia. The study will be conducted at Erzincan Community Mental Health Center (TRSM) between October 2026 and January 2027. A total of 64 participants (32 experimental, 32 control) will be recruited from schizophrenia patients registered at the center. The experimental group will receive 8 structured group sessions based on ACT principles integrated into nursing practice (45-60 minutes per session, once weekly), while the control group will receive routine care only. Pre-test and post-test measurements will be obtained using the Observable Social Cognition Rating Scale (OSCARS), the Difficulties in Emotion Regulation Scale-Brief Form (DERS-16), and the Acceptance and Action Questionnaire-II (AAQ-II).

Schizophrenia is a chronic psychiatric disorder associated with significant impairments in social cognition, emotion regulation, and psychological flexibility. These impairments contribute to social withdrawal, functional decline, and reduced quality of life. While pharmacological treatments address positive symptoms, psychosocial interventions targeting functional outcomes remain underdeveloped, especially those delivered within a nursing framework.

Acceptance and Commitment Therapy (ACT) is a third-wave cognitive behavioral approach centered on psychological flexibility, defined as the ability to contact the present moment fully and to persist in or change behavior in the service of chosen values. ACT's core processes - cognitive defusion, acceptance, present-moment contact, self-as-context, values clarification, and committed action - offer a theoretically coherent intervention framework for addressing the functional deficits seen in schizophrenia.

This study integrates ACT principles into nursing practice through structured group sessions. The intervention program was developed based on a review of the literature and will be evaluated for content validity by at least twelve experts in psychiatric nursing, psychology, and psychiatry prior to implementation. The program consists of 8 weekly sessions (45-60 min each), covering the following themes: 1. Introduction and ACT psychoeducation; 2. Present-moment contact and mindfulness; 3. Emotion awareness and acceptance; 4. Cognitive defusion; 5. Self-as-context and social cognition; 6. Values clarification; 7. Committed action and flexible coping; 8. Consolidation and relapse prevention.

Sample size was determined by G*Power 3.1 power analysis based on three outcome variables. The largest required sample (n = 58) was drawn from the emotion regulation variable (mean scores: 28.06 ± 11.58 vs. 19.08 ± 16.23; effect size d = 0.82; 95% CI; alpha = 0.05; power = 85%). Adding a 10% buffer for attrition yields a total sample of 64 (32 experimental + 32 control). Randomization will be performed using a computer-generated randomization sequence by an independent researcher to prevent selection bias.

Blinding: Due to the nature of psychosocial interventions, participant and investigator blinding is not possible. Outcome assessors will not be involved in the intervention to reduce performance bias. Data will be analyzed using SPSS 22.0; paired comparisons will use Dependent t-Test or Wilcoxon Signed-Rank Test; between-group comparisons will use Independent t-Test or Mann-Whitney U Test. Statistical significance is set at p < 0.05.

After data collection is complete, control group participants will receive a condensed 2-session version of the ACT-based program as an ethical courtesy.

Inclusion Criteria:

• Diagnosed with schizophrenia (ICD-10/DSM-5) and followed at Erzincan Community Mental Health Center (TRSM)
• Registered at Erzincan TRSM
• Duration of schizophrenia diagnosis of at least 6 months
• No cognitive or sensory (hearing/visual) deficit that would prevent participation
• Literate
• Provides written informed consent to participate

Exclusion Criteria:

• Comorbid psychiatric diagnosis other than schizophrenia
• Active acute psychotic episode at enrollment

Discontinuation / Withdrawal Criteria

• Voluntary withdrawal from the study
• Acute psychotic relapse during the study period
• Additional psychiatric diagnosis during the study period
• Radical change in medication type or dosage during the study period
• Incomplete responses on data collection forms
• Completion of less than 80% of assigned homework

Individual participant data will not be shared outside of the research team to ensure participant confidentiality and data privacy in accordance with institutional ethics committee approval and local data protection regulations.