Brief Psychoanalytic Therapy Versus Cognitive Behavioral Therapy for Major Depressive Disorder

Background and rationale Major depressive disorder is a leading cause of disability worldwide. Cognitive behavioral therapy (CBT) is the most extensively studied psychotherapy for depression, and short-term psychodynamic/psychoanalytic therapies have also shown efficacy in randomized trials. Direct comparisons of the two approaches remain limited, particularly in Türkiye, and few trials have examined whether each therapy works through its theoretically proposed mechanism.

Design Single-site, three-arm, parallel-group, randomized controlled trial with assessor-blinded outcome evaluation. Ninety adults with a DSM-5-TR diagnosis of major depressive disorder will be randomized in a 1:1:1 ratio to brief psychoanalytic therapy (BPT), CBT, or waitlist plus treatment as usual (WL-TAU).

Randomization and allocation concealment A computer-generated sequence with permuted blocks of 3 and 6 will be prepared by a researcher not involved in recruitment, assessment or treatment. Randomization will be stratified by current antidepressant use (yes/no) and baseline severity (HAM-D-17 14-18 vs. 19 or higher). Allocation will be concealed in sequentially numbered, sealed, opaque envelopes opened only after baseline assessment.

Blinding Clinician-rated outcomes (HAM-D-17) will be obtained by an independent assessor blind to group allocation. Participants will be instructed not to disclose their allocation. At week 18, the assessor will record a guess of each participant's group to evaluate blinding integrity. Participants and therapists cannot be blinded.

Interventions Brief psychoanalytic therapy: 18 weekly individual sessions of 50 minutes, manualized according to Luborsky's supportive-expressive model and the unified protocol for short-term psychodynamic therapy of depression (Leichsenring \& Schauenburg, 2014). Phases: alliance building and formulation of a focal Core Conflictual Relationship Theme (sessions 1-4); working through the focal conflict, defenses, self-criticism, loss and aggression, including here-and-now relational patterns (sessions 5-14); termination phase focusing on separation and loss (sessions 15-18).

CBT: 18 weekly individual sessions of 50 minutes based on Beck's cognitive therapy for depression. Phases: psychoeducation and behavioral activation (sessions 1-4); identification and restructuring of automatic thoughts (sessions 5-12); modification of intermediate and core beliefs (sessions 13-16); relapse prevention (sessions 17-18). Structured homework is assigned each session.

Waitlist plus treatment as usual: participants continue routine psychiatric follow-up with antidepressant doses held stable and receive no psychotherapy for 18 weeks. Brief non-therapeutic safety check-in calls are made every 4 weeks. After the week-18 assessment, participants are offered either active therapy.

In all arms, participants taking antidepressants must have been on a stable dose for at least 8 weeks before enrollment and agree to keep the dose unchanged during the 18-week treatment phase. Sessions may be completed within a window of up to 20 weeks to accommodate missed appointments.

Therapists and treatment fidelity Each arm will be delivered by separate licensed clinical psychologists trained in the respective modality, with weekly supervision. All sessions will be audio-recorded with consent. A random 20% of sessions will be rated for adherence using the Comparative Psychotherapy Process Scale (psychodynamic-interpersonal and cognitive-behavioral subscales), and CBT sessions additionally with the Revised Cognitive Therapy Scale (CTS-R).

Assessments Diagnosis will be established by a psychiatrist and confirmed with the Structured Clinical Interview for DSM-5, Clinician Version (SCID-5-CV). Outcomes will be assessed at baseline, week 9 and week 18 in all arms, and at 6- and 12-month follow-up in the two active arms. All instruments are used in their validated Turkish versions: Hamilton Depression Rating Scale (HAM-D-17), Beck Depression Inventory-II, Beck Anxiety Inventory, WHOQOL-BREF-TR, Automatic Thoughts Questionnaire, Defense Style Questionnaire-40, and Working Alliance Inventory (active arms, sessions 3 and 12).

Safety monitoring Suicidal ideation will be monitored at every assessment (HAM-D item 3, BDI-II item 9) and weekly by therapists. Participants in any arm showing clinically significant deterioration (an increase of 25% or more in HAM-D-17 from baseline) or emergent suicide risk (HAM-D item 3 score of 3 or higher) will be referred immediately for appropriate clinical care. These participants will remain in the intention-to-treat analysis. Adverse events will be recorded throughout.

Sample size With 30 participants per arm, the study has 80% power (two-tailed alpha = .05) to detect a between-group effect of d = 0.80 for each active therapy versus waitlist, allowing for approximately 15% attrition. The study is not powered for equivalence or non-inferiority testing between the two active therapies; this comparison is exploratory.

Statistical analysis Primary analyses will follow the intention-to-treat principle using linear mixed-effects models with group, time and group-by-time interaction as fixed effects, baseline HAM-D-17 as a covariate, and restricted maximum likelihood estimation for missing data. The two primary contrasts (BPT vs. WL-TAU; CBT vs. WL-TAU) will be adjusted with the Holm procedure. Response (reduction of 50% or more in HAM-D-17) and remission (HAM-D-17 of 7 or less) will be analyzed with logistic regression. Mediation analyses will test whether change in defense style (DSQ-40) and automatic thoughts (ATQ) mediates outcomes in BPT and CBT, respectively. A per-protocol analysis (at least 12 sessions attended) will serve as a sensitivity analysis.