MDD

Major Depressive Disorder (MDD) is a common mental health condition characterized by a persistent low mood or loss of interest or pleasure, along with additional symptoms that affect daily functioning. To meet diagnostic criteria, symptoms must be present for at least two weeks and cause clinically significant distress or impairment. MDD is distinct from brief sadness and can lead to substantial impairment in work, social life, and self-care.

Core symptoms typically include depressed mood most of the day, markedly diminished interest or pleasure in activities, and changes in appetite or sleep. Other frequent features are psychomotor agitation or retardation, fatigue, feelings of worthlessness or inappropriate guilt, diminished ability to think or concentrate, and recurrent thoughts of death or suicide. At least five symptoms must be present during the same 2-week period, with one being either depressed mood or anhedonia.

Etiology is multifactorial, involving genetic vulnerability, neurobiological changes, and environmental stressors. Risk factors include a family history of depression, prior episodes, chronic medical conditions, substance use, trauma, and low social support.

Diagnosis is made by clinical assessment using standardized criteria (such as DSM-5-TR) and by ruling out other medical or psychiatric conditions. Screening tools, like the PHQ-9, can aid identification, but a formal evaluation is required for diagnosis.

Treatment is typically multimodal. First-line approaches for moderate to severe MDD include psychotherapy (cognitive-behavioral therapy, interpersonal therapy) and pharmacotherapy (most commonly selective serotonin reuptake inhibitors or serotonin-norepinephrine reuptake inhibitors). Some patients benefit from combination therapy, escalation to other medications, or procedures such as electroconvulsive therapy in treatment-refractory cases. Ongoing maintenance treatment reduces relapse risk, and lifestyle factors such as regular exercise, sleep regulation, and social support can support recovery. Note: MDD can also refer to Model-Driven Development in software engineering.