Mental Severe Severity

Major Depressive Disorder

Adults Both Reviewed by Quick Care Medical Team
Overview Symptoms Causes Prevention Treatment

Overview

Major depressive disorder is a clinical mental health condition marked by persistent low mood or loss of interest, with significant impact on daily functioning.

How it affects the body and mind:

  • Alters sleep, appetite, concentration, and energy.
  • Increases physical symptoms such as fatigue and body aches.
  • Can impair work, relationships, and self-care; severe cases may include suicidal thoughts.

Symptoms

Key symptoms (usually present most days for at least 2 weeks):

Symptoms vary between individuals but tend to interfere with normal routine and relationships.

  • Persistent sadness or emptiness
  • Loss of interest in usual activities
  • Sleep changes (insomnia or oversleeping)
  • Appetite or weight changes
  • Poor concentration, guilt, hopelessness, or thoughts of self-harm

Causes

Contributing factors:

In most cases, depression develops from a combination of biological and psychosocial factors.

  • Genetic vulnerability and family history
  • Stressful life events and chronic social stress
  • Neurochemical and hormonal factors
  • Coexisting chronic medical illnesses
  • Substance misuse

Prevention

Protective steps:

Early help-seeking is one of the strongest protective actions for long-term recovery.

  • Seek early support for persistent stress or mood changes.
  • Maintain sleep routine, regular physical activity, and social connection.
  • Reduce alcohol and avoid recreational drugs.
  • Follow treatment plans for chronic physical illnesses.
  • Use crisis support immediately for suicidal thoughts.

Treatment

Evidence-based treatment includes psychotherapy (for example CBT), antidepressant medication when indicated, lifestyle support, and regular follow-up.

Urgent psychiatric evaluation is required if there is suicidal intent, self-harm risk, or severe functional decline.

Trusted sources: WHO Depression, CDC Mental Health, APA and NIMH resources.

Quick Facts
Category Mental
Severity Severe
Age Group Adults
Gender Both
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