Definition
Major Depressive Disorder is a common mood disorder characterized by persistent sadness, loss of interest or pleasure in activities, and a variety of emotional and physical symptoms that significantly impair daily functioning.
Core Symptoms (DSM-5 Criteria)
At least five of the following symptoms must be present most of the day, nearly every day, for at least two weeks, and must cause significant distress or impairment:
- Depressed mood as
- Loss of interest or pleasure (anhedonia)
- Significant weight loss or gain, or changes in appetite
- Insomnia or hypersomnia de hi
- Psychomotor agitation or retardation
- Fatigue or loss of energy
- Feelings of worthlessness or excessive guilt
- Diminished ability to think, concentrate, or make decisions
- Recurrent thoughts of death, suicidal ideation, or suicide attempt
Subtypes / Specifiers
- With anxious distress
- With mixed features
- With melancholic features
- With atypical features
- With psychotic features
- With catatonia
- With peripartum onset
- With seasonal pattern (seasonal affective disorder)
Prevalence
- Lifetime prevalence: ~16–20% of adults
- Women are approximately twice as likely to experience MDD as men
Typical Age of Onset
- Most commonly develops in late adolescence to early adulthood (ages 18–25)
- Can occur at any age
Risk Factors
- Genetic: Family history of depression or other mood disorders we
- Biological: Neurotransmitter imbalances (serotonin, norepinephrine, dopamine), hormonal changes
- Psychological: Negative thinking patterns, low self-esteem, trauma, chronic stress
- Environmental: Childhood adversity, social isolation, major life stressors
Course and Duration
- Symptoms typically last at least two weeks per episode
- Episodes can recur; many individuals experience multiple episodes over their lifetime
- Untreated, episodes may last months or even years
Impact and Complications
- Impaired social, occupational, and academic functioning
- Increased risk of substance use disorders
- Elevated risk of suicide
Treatment Approaches
- Psychotherapy
- Cognitive Behavioral Therapy (CBT)
- Interpersonal Therapy (IPT)
- Psychodynamic Therapy
- Medications
- SSRIs, SNRIs, atypical antidepressants, tricyclic antidepressants
- Other Interventions
- Electroconvulsive Therapy (ECT)
- Transcranial Magnetic Stimulation (TMS)
- Lifestyle interventions: exercise, sleep hygiene, stress management
Prognosis
- With treatment, most people experience significant symptom relief
- Early intervention improves outcomes
- Chronic or recurrent depression may require long-term management
Resources & Support
- American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed., American Psychiatric Publishing, 2013.
- Mental Health America. Mental Health America. https://www.mhanational.org. Accessed 4 Sept. 2025.
- National Institute of Mental Health. NIMH. https://www.nimh.nih.gov. Accessed 4 Sept. 2025.
- National Alliance on Mental Illness. NAMI. https://www.nami.org. Accessed 4 Sept. 2025.
- “SAMHSA Helpline: 1-800-662-HELP (4357).” Substance Abuse and Mental Health Services Administration, https://www.samhsa.gov/find-help/national-helpline. Accessed 4 Sept. 2025.
- World Health Organization. WHO Mental Health. https://www.who.int/mental_health. Accessed 4 Sept. 2025
