Depression
Depression is a persistent low mood or loss of interest that impairs daily functioning, defined per DSM-5-TR and screened per USPSTF guidance.
Symptoms
Persistent sadness or loss of interest in activities, changes in sleep or appetite, 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, chronic illness, and life stressors; a family history of depression raises risk substantially.
How it is evaluated
The PHQ-9 questionnaire is the standard screening and severity tool used in primary care and integrative settings alike.
Treatment
Evidence-based psychotherapy, antidepressants, and lifestyle measures -- exercise, sleep regulation, and light therapy for seasonal patterns -- are all first-line per the American College of Physicians living guideline. St. John's wort has real evidence for mild depression but carries a significant interaction risk with prescription antidepressants and other medications, so it should never be combined with them without medical guidance.
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 also warrants urgent evaluation.