Skip to content

Depression

Basics

  • Primary mood disorder with sustained sadness and/or decreased interest.
  • Lifetime prevalence ~20.6%; onset typically around age 30.
  • Higher risk in females (2:1 ratio).

Etiology and Pathophysiology

  • Poorly understood; genetic contribution with ~37% concordance in twins.
  • Risk factors include adverse life events, family history, comorbid medical conditions.

Diagnosis

DSM-5 Criteria for Major Depressive Disorder (MDD):

  • ≥5 symptoms during same 2-week period, at least one must be depressed mood or anhedonia.
  • Symptoms include: dysphoria, anhedonia, appetite change, sleep disturbances, fatigue, psychomotor changes, concentration issues, guilt, suicidal ideation.
  • Symptoms cause functional impairment.
  • Exclude substance or medical causes.

History

  • "SIGECAPS" mnemonic: Sleep, Interest, Guilt, Energy, Concentration, Appetite, Psychomotor, Suicidality.
  • Gender differences in presentation (women: somatic complaints; men: aggression, substance use).
  • Pediatric: irritability, somatic complaints, concentration issues.
  • Geriatric: may mimic cognitive decline; use Geriatric Depression Scale (GDS-15).

Physical Exam

  • Assess mental status, mood, affect, cognition, speech, thought processes, insight, judgment.

Differential Diagnosis

  • Bipolar disorder (depressed phase)
  • Adjustment disorder
  • Medical conditions: hypothyroidism, adrenal disease, diabetes, liver/renal failure
  • Substance-induced
  • Other psychiatric disorders

Diagnostic Tests

  • Screening tools: PHQ-9 (after positive PHQ-2), Beck Depression Inventory, GDS-15 (geriatrics).
  • Labs: CBC, electrolytes, liver/kidney function, TSH, RPR, HIV, vitamin D, B12, folate, pregnancy test as indicated.
  • Imaging: Brain CT/MRI if organic cause suspected.

Treatment

General Measures

  • Combine pharmacotherapy and psychotherapy for best outcomes.
  • Psychotherapy options:
  • Cognitive-behavioral therapy (CBT)
  • Interpersonal psychotherapy (IPT)
  • Psychodynamic therapy
  • Family/marital therapy
  • Problem-solving and supportive therapy

Medications

  • Start low dose; monitor for 4–6 weeks before deeming ineffective.

First Line

  • SSRIs: citalopram, escitalopram (QT risk), fluoxetine (FDA approved for teens), paroxetine (avoid elderly), sertraline.
  • SNRIs: desvenlafaxine, duloxetine, venlafaxine.
  • Serotonin modulators: trazodone, vilazodone, vortioxetine.

Second Line

  • TCAs (amitriptyline, nortriptyline, imipramine) – caution in elderly.
  • Atypical antidepressants: bupropion, mirtazapine.
  • MAOIs (phenelzine, selegiline) – require washout period.

Alerts

  • Black box warning for suicidality risk in children and young adults.
  • Beware serotonin syndrome.
  • Antidepressants may induce mania in bipolar disorder.
  • Discontinuation syndrome (FINISH mnemonic).

Referral

  • Psychotic or treatment-resistant depression.

Additional Therapies

  • Electroconvulsive therapy (ECT) for severe/refractory cases.
  • Emerging: rTMS, deep brain stimulation, ketamine, anti-inflammatory agents, psilocybin.

Complementary Medicine

  • Exercise and St. John’s wort (conditional recommendation).
  • Insufficient evidence for tai chi, omega-3s, acupuncture monotherapy.

Inpatient Considerations

  • Admit for suicide risk or severe impairment.

Ongoing Care

  • Patient education on delayed medication effect (2–4 weeks).
  • Encourage exercise, sleep hygiene, nutrition, avoid tobacco/alcohol.
  • National Suicide Prevention Lifeline: 800-273-TALK (8255).

Prognosis

  • Complete remission uncommon; partial remission common.
  • Relapses frequent; monitoring essential.

ICD10 Codes:
- F32.9 Major depressive disorder, single episode, unspecified
- F33.9 Major depressive disorder, recurrent, unspecified
- F34.1 Dysthymic disorder

Clinical Pearls:
- Combination therapy yields best outcomes.
- Close monitoring is essential for safety and effectiveness.