Major Depressive Disorder
Major depressive disorder (MDD) requires five or more symptoms over a 2-week period, including depressed mood or loss of interest, per DSM-5-TR.
Symptoms
Persistent sadness or loss of interest in nearly all activities, along with changes in sleep, appetite, or weight, fatigue, difficulty concentrating, feelings of worthlessness, and in more severe cases, thoughts of death or suicide.
Causes and risk
A combination of genetics, brain chemistry, life stressors, and chronic illness; family history of depression raises risk substantially.
How it is evaluated
The PHQ-9 questionnaire is widely used to screen and monitor severity, with a score of 10 or higher carrying roughly 85% sensitivity and specificity for MDD, per JAMA data.
Treatment
CBT alone suits mild depression; a second-generation antidepressant, psychotherapy, or the combination are all first-line for moderate-to-severe MDD, per the American College of Physicians living guideline.
When to seek care
Any thoughts of suicide or self-harm are a medical emergency -- call 911 or the 988 Suicide and Crisis Lifeline immediately. A sudden worsening of symptoms or inability to care for yourself also warrants urgent evaluation.