What are the diagnostic criteria for major depressive disorder?

Diagnostic Criteria for Major Depressive Disorder

Major Depressive Disorder (MDD) is diagnosed when a patient exhibits at least 5 of 9 specific symptoms during the same 2-week period, with at least one symptom being either depressed mood or loss of interest/pleasure in activities. 1

Core Diagnostic Criteria

To meet the diagnostic threshold for MDD, the following criteria must be present:

Required Symptoms (at least one must be present)

1. Depressed mood most of the day, nearly every day (can be irritable mood in children/adolescents)
2. Markedly diminished interest or pleasure in all or almost all activities most of the day, nearly every day

Additional Symptoms (total of 5 or more symptoms required, including at least one of the above)

1. Significant weight loss when not dieting or weight gain (e.g., >5% of body weight in a month), or decreased or increased appetite nearly every day
2. Insomnia or hypersomnia nearly every day
3. Psychomotor agitation or retardation nearly every day (observable by others)
4. Fatigue or loss of energy nearly every day
5. Feelings of worthlessness or excessive/inappropriate guilt nearly every day
6. Diminished ability to think or concentrate, or indecisiveness, nearly every day
7. Recurrent thoughts of death, suicidal ideation without a specific plan, or a suicide attempt or specific plan for committing suicide 1, 2

Duration and Impact Requirements

• Symptoms must persist for at least 2 weeks
• Symptoms must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning 1, 2

Exclusion Criteria

For a diagnosis of MDD to be valid, the following conditions must be ruled out:

• Symptoms are not attributable to the physiological effects of a substance or another medical condition
• The episode is not better explained by schizoaffective disorder, schizophrenia, schizophreniform disorder, delusional disorder, or other psychotic disorders
• There has never been a manic episode or hypomanic episode 1, 3
• Symptoms are not better accounted for by bereavement (i.e., after the loss of a loved one) 3

Clinical Assessment Tools

Several validated screening and assessment tools can be used to support diagnosis:

• Patient Health Questionnaire-9 (PHQ-9): A 9-item self-report scale assessing symptoms of major depressive disorder as defined by DSM criteria 1
• Hamilton Depression Rating Scale (HAM-D): A 17-item clinician-administered scale where scores of 7-17 suggest mild depression, 18-24 moderate depression, and ≥25 severe depression 1
• Hospital Anxiety and Depression Scale (HADS): A 14-item self-report measure with scales for both anxiety and depression; scores ≥8 on the depression scale indicate possible depression 1

Important Clinical Considerations

• Research shows that very few patients (1.5%) meet five or more criteria without experiencing either low mood or loss of interest/pleasure, confirming the importance of these two cardinal symptoms 4
• The diagnostic process should include assessment of symptom severity, functional impairment, and suicide risk 2
• Laboratory tests may be considered to rule out medical conditions that can mimic depression (e.g., thyroid disorders, anemia) 2
• Comorbid conditions such as anxiety disorders are common and should be assessed 1

Treatment Implications of Diagnosis

Once diagnosed, treatment options include:

• Cognitive behavioral therapy or second-generation antidepressants (strong recommendation, moderate-quality evidence) 1
• Treatment should be continued for at least 4-9 months after achieving remission to prevent relapse 5
• Regular monitoring using standardized measures (e.g., PHQ-9) every 2-4 weeks is recommended during treatment 5

Common Pitfalls in Diagnosis

• Failing to distinguish between normal sadness and clinical depression
• Not accounting for cultural variations in symptom presentation
• Overlooking medical conditions or medications that can cause depressive symptoms
• Missing bipolar disorder, which requires different treatment approaches
• Not thoroughly assessing suicide risk, which requires immediate intervention if present 3