What are the diagnostic criteria for major depressive disorder?

Diagnostic Criteria for Major Depressive Disorder

Major depressive disorder requires at least 5 of 9 specific symptoms present during the same 2-week period, with at least one symptom being either depressed mood or loss of interest/pleasure (anhedonia), and these symptoms must cause clinically significant distress or functional impairment. 1

Core Diagnostic Requirements

Symptom Count and Duration

• Five or more symptoms must be present during the same 2-week period and represent a change from previous functioning 1
• At least one of the five symptoms must be either:
  • Depressed mood most of the day, nearly every day (in children and adolescents, this can manifest as irritable mood) 1
  • Markedly diminished interest or pleasure in all, or nearly all, activities most of the day, nearly every day 1

The Nine DSM Symptom Criteria

The following symptoms constitute the diagnostic criteria, with any 5 qualifying for diagnosis when the core symptom requirement is met:

1. Depressed mood most of the day, nearly every day (can be irritable mood in youth) 1

2. Anhedonia - markedly diminished interest or pleasure in activities most of the day, nearly every day 1

3. Significant weight change - weight loss when not dieting or weight gain (>5% of body weight in a month), or increased/decreased appetite nearly every day (in children/adolescents, includes failure to make expected weight gains) 1

4. Sleep disturbance - insomnia or hypersomnia nearly every day 1

5. Psychomotor changes - agitation or retardation nearly every day, observable by others (not merely subjective feelings of restlessness or being slowed down) 1

6. Fatigue or loss of energy nearly every day 1

7. Worthlessness or guilt - feelings of worthlessness or excessive/inappropriate guilt (which may be delusional) nearly every day 1

8. Cognitive impairment - diminished ability to think or concentrate, or indecisiveness, nearly every day 1

9. Suicidal ideation - recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, suicide attempt, or a specific plan to commit suicide 1

Essential Exclusion Criteria

What Must Be Ruled Out

Before diagnosing major depressive disorder, you must exclude:

• Bipolar disorder - symptoms do not meet criteria for a mixed episode (nearly daily fluctuations qualifying for both manic and major depressive episodes) 1

• Substance-induced depression - symptoms are not due to direct physiologic effects of drugs of abuse or medications 1

• Medical conditions - symptoms are not due to general medical conditions such as hypothyroidism 1

  • Check thyroid function, complete metabolic panel, complete blood count, vitamin B12/folate levels 2
  • Review medications for mood-altering side effects (interferon, corticosteroids, beta-blockers) 2
  • Rule out uncontrolled pain, fatigue, delirium from infection or electrolyte imbalance 3, 4

• Bereavement - symptoms are not better accounted for by bereavement, unless symptoms persist longer than 2 months OR are characterized by marked functional impairment, morbid preoccupation with worthlessness, suicidal ideation, psychotic symptoms, or psychomotor retardation 1

Functional Impairment Requirement

• The symptoms must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning 1
• Assessment of functional impairment is crucial in determining the diagnosis 3

Practical Screening Approach

Two-Step PHQ-9 Method

Use the PHQ-9 as the primary diagnostic framework, starting with the two core symptoms (depressed mood and anhedonia), then proceeding to the remaining seven symptoms if either core symptom is present 3, 4

• Initial screening uses the first 2 PHQ-9 items 4
• Complete full 9-item assessment if either item scores ≥2 4
• Never omit item 9 regarding self-harm - this artificially lowers scores and misses critical safety information 2, 3, 4

Severity Classification

Severity is based on symptom count, intensity, and level of impairment: 1

• Mild depression: 5-6 symptoms that are mild in severity with only mild functional impairment 1

• Moderate depression: Falls between mild and severe categories 1

• Severe depression: All depressive symptoms present OR severe functional impairment (unable to leave home) OR presence of:

  • Specific suicide plan, clear intent, or recent attempt 1
  • Psychotic symptoms 1
  • Family history of first-degree relatives with bipolar disorder 1

Critical Diagnostic Pitfalls

Common Errors to Avoid

• Do not skip the suicidal ideation question - this is the most dangerous omission and misses critical risk information 2, 3, 4

• Do not fail to complete the full 9-item PHQ-9 if you administered only the initial 2-item screen 2

• Do not overlook medical causes before diagnosing a primary mood disorder 2, 4

• Do not assume the core symptom requirement is unnecessary - while research suggests high concordance without this requirement 5, current diagnostic standards mandate at least one core symptom 1

Special Population Considerations

Age-Specific Modifications

• Children and adolescents: Depressed mood can manifest as irritable mood 1
• Weight criteria should include failure to make expected weight gains 1

Elderly Patients

• Use the Geriatric Depression Scale (GDS-15) instead of PHQ-9 2, 3, 4
• GDS focuses on affective symptoms and excludes somatic items that may be confounded by medical illness 3

Cognitively Impaired Patients

• The PHQ-9 loses accuracy in patients with cognitive impairment 2, 3, 4
• Use alternative assessment methods such as informant-based tools 4

Immediate Safety Assessment

If any self-harm ideation is endorsed, immediately refer for emergency psychiatric evaluation regardless of the total PHQ-9 score 2

• Facilitate a safe environment with one-to-one observation if self-harm risk is present 2
• The frequency and specificity of self-harm thoughts are most critical for risk assessment 2