Major
Depressive Disorder
A mood disorder characterized by persistent depressed mood or loss of interest/pleasure, accompanied by cognitive, behavioral, and somatic symptoms that significantly impair functioning.
Critères diagnostiques du DSM-5-TR
Core Symptom Requirement
5+ symptoms during the same 2-week period
- • At least one must be (1) depressed mood or (2) loss of interest/pleasure
Symptom Cluster
Clinical manifestations:
- • Depressed Mood (Subjective or observed)
- • Anhedonia (Markedly diminished interest or pleasure)
- • Weight/Appetite Change (Significant loss or gain)
- • Sleep Disturbance (Insomnia or hypersomnia)
- • Psychomotor Agitation/Retardation (Observable)
- • Fatigue/Loss of Energy
- • Worthlessness/Guilt (Excessive or inappropriate)
- • Concentration Difficulties (or indecisiveness)
- • Suicidal Ideation (Recurrent thoughts of death)
Additional Requirements
Diagnostic caveats:
- • Symptoms cause significant distress or impairment
- • Not attributable to substance use or medical condition
- • No history of manic or hypomanic episodes
Protocoles d'évaluation
Outils validés pour le dépistage et le suivi de la sévérité
PHQ-9
Patient Health Questionnaire-9
Brief 9-item self-report measure directly corresponding to DSM-5-TR depression criteria; most widely used in primary care.
0-4 minimal, 5-9 mild, 10-14 moderate, 15-19 moderately severe, 20-27 severe depression
BDI-II
Beck Depression Inventory-II
21-item self-report assessing cognitive, affective, somatic, and vegetative symptoms over past 2 weeks.
0-13 minimal, 14-19 mild, 20-28 moderate, 29-63 severe depression
MADRS
Montgomery-Åsberg Depression Rating Scale
Clinician-rated 10-item scale sensitive to change; preferred for treatment trials and monitoring.
0-6 normal, 7-19 mild, 20-34 moderate, >34 severe; change ≥50% indicates response
QIDS-SR16
Quick Inventory of Depressive Symptomatology
16-item self-report covering all 9 DSM symptom domains; sensitive to change, useful for monitoring.
0-5 none, 6-10 mild, 11-15 moderate, 16-20 severe, 21-27 very severe
Causes et étiologie
Neurobiological
- Monoamine dysregulation (serotonin, norepinephrine, dopamine)
- Reduced hippocampal volume and neurogenesis
- Prefrontal cortex hypoactivity
- Amygdala hyperactivity (negative emotional processing)
- HPA axis dysfunction (cortisol dysregulation)
- Neuroinflammation and cytokine elevation
Genetic
- Heritability: 30-40% (moderate genetic component)
- Polygenic risk involving 100+ genes
- 5-HTTLPR polymorphism (serotonin transporter)
- BDNF gene variants (neuroplasticity)
- First-degree relatives have 2-3x increased risk
Environmental
- Early childhood adversity and trauma
- Chronic stress and major life events
- Social isolation and lack of support
- Socioeconomic disadvantage
- Medical illness (stroke, cancer, chronic pain)
- Substance use (alcohol, sedatives)
Psychological
- Negative cognitive schemas (Beck's cognitive triad)
- Rumination and cognitive inflexibility
- Learned helplessness and external locus of control
- Perfectionism and self-criticism
- Reduced reward sensitivity (anhedonia)
Sources scientifiques
PHQ-9 Validation
Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. 2001;16(9):606-613.
DSM-5-TR Criteria
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR). 2022.
CBT Efficacy Meta-Analysis
Cuijpers P, Berking M, et al. A meta-analysis of cognitive-behavioural therapy for adult depression. J Affect Disord. 2013;142(1-3):1-8.
Antidepressant Efficacy (STAR*D)
Rush AJ, Trivedi MH, et al. Acute and longer-term outcomes in depressed outpatients requiring one or several treatment steps: STAR*D trial. Am J Psychiatry. 2006;163(11):1905-1917.
Neurobiology of Depression
Duman RS, Aghajanian GK, et al. Synaptic dysfunction in depression: potential therapeutic targets. Science. 2012;338(6103):68-72.
Behavioral Activation
Dimidjian S, Hollon SD, et al. Randomized trial of behavioral activation, cognitive therapy, and antidepressant medication. J Consult Clin Psychol. 2006;74(4):658-670.
Recherche et actualités sur MDD Clinical Guide: PHQ-9, DSM-5-TR and Treatment Tiers
Nouvelles, recherches et politiques récentes provenant de sources fiables.