Psychiatry
Major Depressive Disorder
주요우울장애
Mood disorder with depressed mood/anhedonia lasting ≥2 weeks
- How common
- Lifetime prevalence 17% (F:M 2:1)
- Typical age
- Mean onset early 30s
What is it?
Monoamine (5-HT/NE/DA) deficiency, HPA axis hyperactivity, hippocampal/PFC atrophy, reduced BDNF.
Commonly affected: Prefrontal cortex, limbic (amygdala/hippocampus), reward circuit (NAc/VTA)
How it develops
- VulnerabilitySLC6A4 polymorphism + early-life trauma stress load
- Monoamine deficitReduced 5-HT/NE/DA synaptic transmission
- HPA & neurotoxicityElevated cortisol shrinks hippocampus/PFC
- Circuit dysfunctionDMN overactive, reward circuit underactive
Symptoms
- Depressed moodSad/empty nearly every day, most of day
- AnhedoniaLoss of interest/pleasure
- Suicidal ideationRecurrent thoughts of death
- Sleep/appetite changeInsomnia/hypersomnia, weight change
- Cognitive impairmentReduced concentration/decision-making
How it is examined
- DSM-5 criteria≥5 of 9 symptoms × ≥2 weeks + functional impairment
- PHQ-9 screening0–27, ≥10 moderate depression
- Suicide risk assessmentC-SSRS: plan/means/history
Imaging
MRI: reduced hippocampal volume and PFC atrophy reported.
- Hippocampal atrophy
- PFC atrophy
PET shows reduced subgenual ACC metabolism.
- Reduced ACC metabolism
Non-surgical care
- SSRI first-lineSertraline, escitalopram (4–6 wk onset)
- SNRIVenlafaxine, duloxetine (refractory)
- CBTCognitive restructuring, behavioral activation
- IPTInterpersonal conflict/role transitions
- Exercise/sleep hygiene3x/wk aerobic + sleep regularity
Conservative options are generally tried first. Medications listed here can have side effects — discuss them with your prescriber.
When surgery is considered
Treatment-resistant depression (≥2 failed trials)
Procedures that may be discussed
- ECT (highly effective, rapid)
- rTMS
- Ketamine/esketamine (IV/intranasal)
- VNS
Outlook
60–80% remission possible. Recurrence 50% (1 episode), 90% (≥3). Lifetime suicide rate 10–15%.