Depression (major depressive disorder)

Common symptoms and signs

Depression affects both emotional and physical domains. Not everyone has the same pattern, but common symptoms include:

• Persistent low mood, sadness, or emptiness;
• Marked loss of interest or pleasure in usual activities;
• Changes in appetite or weight and altered sleep (insomnia or oversleeping);
• Fatigue, slowed thinking or psychomotor agitation;
• Difficulty concentrating, indecisiveness, or memory problems;
• Feelings of worthlessness, excessive guilt, or recurrent thoughts of death or suicide.

If suicidal thoughts are present or there is danger to self or others, immediate help should be sought through emergency services or crisis lines: crisis support.

Causes and risk factors

Depression arises from a complex interplay of genetic vulnerability, brain chemistry, personality traits, life events, and medical conditions. Stressful experiences such as loss, trauma, or social isolation can trigger episodes. Chronic illness, substance use, hormonal changes, and certain medications also contribute. Family history increases risk but does not guarantee development of disorder. For general guidance on risk and prevention, see further reading.

Diagnosis and course

Diagnosis is clinical, based on a structured history and symptom checklist by a qualified clinician. Medical evaluation may rule out thyroid problems, vitamin deficiencies, or other causes. Severity ranges from mild to severe; some people recover with treatment, others experience recurrent or persistent depression that requires ongoing management. Early recognition improves outcomes.

Treatment and management

Treatment commonly combines psychological therapies (for example cognitive behavioral therapy or interpersonal therapy), medications (antidepressants), and lifestyle measures such as regular activity, sleep regulation, and social support. For some, psychotherapy alone is effective; others benefit from combined approaches. In severe or treatment-resistant cases, additional options exist including specialized therapies and medical procedures under professional care. For help finding services and self-help strategies, consult local mental health services: service directory.

Important distinctions include unipolar depression (without episodes of mania) versus bipolar disorder (which includes manic or hypomanic periods). Stigma and misunderstanding can delay care, so clear information, supportive social networks, and access to treatment are key parts of recovery and long-term management.