Learning Objectives
Master the diagnostic criteria for Major Depressive Disorder (MDD) and its variants. Learn the SIGECAPS mnemonic, differentiate MDD from Persistent Depressive Disorder, and understand the specific management for seasonal and psychotic features for the USMLE Step 1.
1. Major Depressive Disorder (MDD) Criteria
MDD is characterized by recurrent episodes lasting >= 2 weeks. Diagnosis requires >= 5 of 9 diagnostic symptoms, and one of those must be either depressed mood or anhedonia.
| Mnemonic | Symptom | Clinical Presentation |
|---|---|---|
| S | Sleep | Insomnia or hypersomnia. |
| I | Interest | Anhedonia (loss of interest in pleasurable activities). |
| G | Guilt | Feelings of worthlessness or excessive guilt. |
| E | Energy | Fatigue or loss of energy. |
| C | Concentration | Diminished ability to think or make decisions. |
| A | Appetite | Weight loss or gain; change in appetite. |
| P | Psychomotor | Retardation (slowing down) or agitation. |
| S | Suicidal Ideation | Recurrent thoughts of death or suicide attempts. |
2. MDD Variants and Persistent Depressive Disorder
Depressive disorders vary in duration, severity, and the presence of specific patterns or psychotic features.
| Disorder | Duration/Criteria | Key Clinical Feature |
|---|---|---|
| Persistent Depressive | >= 2 years | Milder than MDD; no remission > 2 months. (Dysthymia). |
| MDD w/ Psychotic Features | Occurs during MDE | Hallucinations/delusions are usually mood-congruent. |
| MDD w/ Seasonal Pattern | >= 2 consecutive years | Episodes occur during specific seasons (usually winter). |
Activity:
3. Management and Treatment Strategies
Treatment involves a combination of psychotherapy, pharmacotherapy, and procedural interventions for resistant cases.
| Intervention | Specific Treatment Options |
|---|---|
| First-line | CBT and SSRIs. |
| Alternatives | SNRIs, mirtazapine, bupropion, and ketamine. |
| Procedural/Severe | ECT (Electroconvulsive therapy) or Light Therapy (for seasonal). |
Activity:
High-Yield Clinical Pearls:
- The Bipolar Screen: Always screen for a history of mania/hypomania before starting antidepressants to avoid triggering a switch.
- Mood Congruence: In MDD with Psychotic Features, delusions often involve themes of guilt, disease, or death (e.g., believing one’s internal organs are rotting).
- Grief vs. MDD: While bereavement can resemble MDD, a formal diagnosis of MDD is made if the full criteria (SIGECAPS) are met.
- Dysthymia Mnemonic: Think of Persistent Depressive Disorder as “2-2-2″—2 years, 2 symptoms, < 2 months remission.