The goal of this clinical trial is to test the efficacy of Acceptance and Commitment Therapy (ACT) as a psychotherapeutic treatment for patients with Bipolar Disorder (BD). The following questions will be investigated:

• The efficacy of ACT in reducing depressive symptoms in patients with BD.
• The efficacy of ACT in improving the quality of life in patients with BD.
• The efficacy of ACT in improving functionality in patients with BD.
• The efficacy of ACT in improving sleep quality in patients with BD.
• The efficacy of ACT in improving psychological flexibility in patients with BD

Participants in the clinical group will undergo 12, 2 hours, weekly sessions of Acceptance and Commitment Therapy, in addition to their regular pharmacological treatment.

Participants in the control group will undergo 3, 2 hours, weekly sessions of Bipolar Disorder Psychoeducation Therapy, in addition to their regular pharmacological treatment.

Scales and assessments will be used to measure study outcomes on 5 different time-points: pre-intervention (month 0), post-intervention (month 3), follow-up 1 (month 6), follow-up 2 (month 9), follow-up 3 (month 12). Mood scales will be assessed every 2 weeks for the duration of treatment and every 4 weeks during the additional 12 week follow-up period.

Results will be compared among both groups to assess the effectiveness of Acceptance and Commitment Therapy as an intervention for syndromic and sub-syndromic depression in bipolar disorder.

Bipolar disorder (BD) is a serious psychiatric disorder characterized by recurrent episodes of mania and depression. The treatment of BD includes a combination of pharmacological medications and psychotherapy to manage episodes and prevent recurrence.

Acceptance and Commitment Therapy (ACT) is an evidence-based psychotherapy. Although there is ample evidence for the efficacy of ACT in the treatment of psychiatric disorders, the literature on ACT for BD is still scarce.There are only five published studies, with three of them being pilot studies.

The present study is justified by the importance to fill a gap in the literature, by aiming to evaluate the effectiveness of ACT as a psychotherapeutic intervention for BD patients and to understand its possible effects mood, quality of life, functionality, sleep, and psychological flexibility on this population.

Main Objective:

To investigate the effectiveness of ACT, in improving syndromic and sub-syndromic depressive symptoms in patients with BD.

Specific objectives:

1. To investigate the efficacy of ACT for improving the quality of life in patients with BD.
2. To investigate the efficacy of ACT in improving functionality in patients with BD.
3. To investigate the efficacy of ACT in improving sleep quality in patients with BD.
4. To investigate the efficacy of ACT in improving psychological flexibility in patients with BD.

Material and Methods:

All participants will be recruited from patients regularly enrolled at the Bipolar Disorder Program - PROMAN - outpatient clinic at Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo. Participants will have access to the Informed Consent Form (ICF), and only those who agree to participate will be included in the study. Randomization Individuals with Bipolar Disorder recruited for the research will be randomized to the ACT arm or Usual Treatment arm through the Online Randomization software.

Procedures:

1. Recruitment will take place in the outpatient clinic of the Bipolar Disorder Program (PROMAN) of the HC-FMUSP Psychiatric Institute and online through the Hospital's social medias.
2. Interested individuals will undergo an initial screening to verify eligibility based on the selection criteria established in the study.
3. Individuals who meet the inclusion criteria will undergo a psychiatric evaluation based on the Standardized Structured Clinical Diagnostic Interview for DSM IV - Axis I Disorders (M.I.N.I.). and complete the initial phase (pre-treatment) instruments via the REDCap platform.
4. Included participants will be randomized into ACT or Psychoeducation group.
5. Participants will be contacted by email or text message with informations regarding the start of treatment.
6. Throughout the intervention, Mood scales (YMRS and MADRS) will be administered periodically (every two weeks)
7. At the end of the intervention, the same assessments administered at baseline will be repeated, as well as at 6, 9 and 12-month follow-ups.

For control purposes, medication changes will be monitored using the MRTF Scale, which allows monitoring of the frequency, type, and reasons for changes in dosages and medications during the intervention protocol. Throughout the study, participants in both groups will continue to receive their usual pharmacological treatment.

Inclusion Criteria:

• Diagnosis of Bipolar Disorder type I and II according to DSM V
• Presence of depressive symptoms (MADRS>12)
• Not undergoing psychotherapy
• Availability to attend in-person group therapy sessions
• Signing consent form

Exclusion Criteria:

• Organic mental disorder
• Presence of manic or hypomanic symptoms (YMRS>12)
• Currently undergoing psychotherapy (not able to pause during the study)
• Major medication change in last 30 days