What diagnosis should be assigned to a patient with a two-month history of depressive mood?

Diagnosis: Major Depressive Disorder

For a patient with two months of depressive symptoms who meets DSM-5 criteria (5 or more symptoms including depressed mood or anhedonia, causing functional impairment), the appropriate diagnosis is Major Depressive Disorder (MDD). 1, 2, 3

Diagnostic Criteria Application

The DSM-5 requires all of the following for MDD diagnosis 1, 2:

Core Requirements:

• Duration: At least 2 weeks of symptoms (your patient meets this at 2 months)
• Symptom count: 5 or more of 9 symptoms during the same 2-week period
• Essential symptom: At least one must be either:
  1. Depressed mood (can be irritable mood in children/adolescents), OR
  2. Loss of interest or pleasure (anhedonia)

The 9 Diagnostic Symptoms:

1. Depressed mood most of the day, nearly every day
2. Markedly diminished interest/pleasure in activities
3. Significant weight change or appetite change
4. Insomnia or hypersomnia
5. Psychomotor agitation or retardation (observable by others)
6. Fatigue or loss of energy
7. Feelings of worthlessness or excessive guilt
8. Diminished concentration or indecisiveness
9. Recurrent thoughts of death or suicidal ideation

Additional Criteria That Must Be Met:

• Functional impairment: Symptoms cause clinically significant distress or impairment in social, occupational, or other important functioning 1, 3
• Not substance-induced: Symptoms not due to drugs, medications, or medical conditions (e.g., hypothyroidism) 1
• Not bereavement alone: If following loss of loved one, symptoms must persist >2 months OR include marked functional impairment, worthlessness, suicidal ideation, psychotic symptoms, or psychomotor retardation 1
• Not a mixed episode: Symptoms don't meet criteria for both manic and depressive episodes 1

Severity Assessment

Once MDD is diagnosed, classify severity 2:

Mild: 5-6 symptoms of mild intensity with mild functional impairment

Moderate: Between mild and severe in symptom count, intensity, and impairment

Severe: All or most symptoms present with severe intensity OR severe functional impairment (unable to leave home) OR presence of:

• Specific suicide plan/intent/recent attempt
• Psychotic symptoms
• First-degree family history of bipolar disorder

Alternative Diagnoses to Consider

If the patient does NOT meet full MDD criteria:

• Persistent Depressive Disorder (Dysthymia): Depressed mood for most days over 2+ years with fewer symptoms than MDD 3
• Adjustment Disorder with Depressed Mood: Emotional/behavioral symptoms within 3 months of identifiable stressor, not meeting MDD criteria 4
• Subsyndromal Depression: Depressive symptoms not meeting MDD or dysthymia thresholds 3

Critical Clinical Pitfalls

Do not diagnose MDD if:

• Symptoms are better explained by bipolar disorder (screen for manic/hypomanic episodes)
• Medical condition is causing symptoms (check thyroid function, rule out other organic causes)
• Substance use is the primary cause
• Patient has fewer than 5 symptoms or duration <2 weeks (unless severe features present)

Important note: Research suggests episodes lasting 4+ days may have equal validity to 2-week episodes 5, but current diagnostic standards require the 2-week minimum. The 2-week criterion remains the standard despite some debate about its optimality.

Next Steps After Diagnosis

Once MDD is confirmed, immediate actions include 6:

• Assess suicide risk (highest in first 1-2 months of treatment)
• Determine severity to guide treatment intensity
• Screen for comorbid conditions (anxiety, substance use)
• Initiate treatment within 1-2 weeks and reassess response by 6-8 weeks