Brief Psychoanalytic Therapy Versus Cognitive Behavioral Therapy for Major Depressive Disorder

The goal of this clinical trial is to learn whether brief psychoanalytic therapy and cognitive behavioral therapy (CBT) reduce depressive symptoms in adults aged 18 to 65 who have been diagnosed with major depressive disorder. The main questions it aims to answer are: * Does brief psychoanalytic therapy reduce depression severity more than a waitlist control condition after 18 weeks? * Does CBT reduce depression severity more than a waitlist control condition after 18 weeks? Researchers will also compare brief psychoanalytic therapy with CBT to explore whether one works better than the other, and will examine whether changes in defense mechanisms and automatic negative thoughts explain improvement in each therapy. Participants will: * Be randomly assigned to brief psychoanalytic therapy, CBT, or a waitlist control group (30 participants per group) * In the therapy groups, attend 18 weekly individual therapy sessions of 50 minutes each * In the waitlist group, continue their usual psychiatric care without psychotherapy for 18 weeks, and then be offered one of the therapies * Complete clinical interviews and questionnaires about depression, anxiety, quality of life, thought patterns and coping styles before treatment, at week 9 and at week 18 * In the therapy groups, complete follow-up assessments 6 and 12 months after treatment ends

Inclusion Criteria: * Primary DSM-5-TR diagnosis of Major Depressive Disorder (single or recurrent episode), established by a psychiatrist and confirmed with the Structured Clinical Interview for DSM-5, Clinician Version (SCID-5-CV) * Hamilton Depression Rating Scale (HAM-D-17) total score of 14 or higher at baseline * Either not taking antidepressant medication, or on a stable antidepressant dose for at least 8 weeks before enrollment and willing to keep the dose unchanged during the 18-week treatment phase * Literate in Turkish and able to attend weekly sessions * Written informed consent Exclusion Criteria: * Bipolar disorder, schizophrenia spectrum or other psychotic disorder, or major depressive disorder with psychotic features * Moderate or severe substance use disorder within the past 6 months * High suicide risk, defined as active suicidal ideation with plan or intent, or a suicide attempt within the past 12 months * Another primary psychiatric diagnosis requiring different treatment (e.g., posttraumatic stress disorder, obsessive-compulsive disorder, eating disorder, or severe personality disorder) * Neurological disorder, dementia, intellectual disability, or a medical condition that could explain the depressive symptoms (e.g., untreated hypothyroidism) * Currently receiving any psychotherapy, or having received cognitive behavioral or psychodynamic therapy within the past 12 months * Electroconvulsive therapy or repetitive transcranial magnetic stimulation within the past 6 months