Guidelines for Diagnosing Major Depressive Disorder
Screening Strategies
- Use the Patient Health Questionnaire‑9 (PHQ‑9), a 9‑item self‑report instrument, to identify individuals who may meet DSM‑5 criteria for major depressive disorder. The tool evaluates depressive symptoms and associated functional impairment. [1][2]3
- Prioritize targeted screening for persons with known risk factors such as personal or family history of mood disorders, prior suicidal behavior, substance use, other psychiatric illnesses, significant psychosocial stressors, frequent somatic complaints, or a history of foster care/adoption. [4][5]
- Recognize that a positive PHQ‑9 score alone does not confirm a diagnosis, especially in low‑risk primary‑care populations where the positive predictive value is limited. 5
Indications for Full Diagnostic Assessment
- Proceed to a comprehensive evaluation when a patient (1) screens positive on a validated instrument, (2) presents with an emotional problem as the chief complaint, or (3) is highly suspected of depression despite a negative screen. 5
Core Diagnostic Criteria (DSM‑5)
Diagnose major depressive disorder when ≥5 of the following 9 symptoms are present ≥2 weeks, representing a change from prior functioning, and at least one symptom is either depressed mood or loss of interest/pleasure. The symptom set includes: depressed mood/irritability, anhedonia, weight/appetite change, sleep disturbance, psychomotor change, fatigue, feelings of worthlessness/guilt, concentration difficulty, and recurrent thoughts of death or suicidal ideation. 6
Additional requirements:
- Symptoms must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning. 1
- Symptoms must not be attributable to the physiological effects of substances or another medical condition. 3
- Symptoms must not be better explained by bereavement or another psychiatric disorder. 1
Essential Assessment Components
- Conduct direct clinical interviews with the individual and, when appropriate, with caregivers or family members to obtain a comprehensive history. 5
- Systematically evaluate functional impairment across domains such as work/school, home, and peer/social settings. 5
- Screen for comorbid psychiatric conditions, given their high prevalence and impact on treatment planning. 5
- Perform a mandatory safety assessment for suicidal ideation, intent, plan, and overall risk of harm to self or others, regardless of the provisional diagnostic impression. 5
- Exclude medical etiologies (e.g., pain, fatigue, delirium, infection, electrolyte disturbances) before confirming a psychiatric diagnosis. [1][2]
Standardized Clinician‑Administered and Self‑Report Scales
| Scale | Format | Interpretation Threshold | Key Features | |
|---|---|---|---|---|
| Hamilton Rating Scale for Depression (HAM‑D) | 17‑item clinician‑administered | 7‑17 = mild, 18‑24 = moderate, ≥25 = severe | Assesses mood, insomnia, agitation, anxiety, weight loss. | [1][2] |
| Beck Depression Inventory (BDI) | Self‑report | ≥20 = clinical depression | Covers behavioral, cognitive, somatic items including suicidal thoughts. | [2] |
| Center for Epidemiologic Studies Depression Scale (CES‑D) | 20‑item self‑report | ≥16 = moderate‑to‑severe symptoms | Relatively unaffected by physical symptom overlap. | [1][3] |
| Hospital Anxiety and Depression Scale (HADS) | 14‑item self‑report (7 depression items) | Depression subscale ≥8 = caseness | Excludes somatic items to reduce medical confounding. | [1][3] |
| Geriatric Depression Scale (GDS) | 30‑item (or 15‑item short form) self‑report | ≥19 (30‑item) or ≥5 (15‑item) = depression requiring follow‑up | Designed for older adults. | [1][3] |
Special Considerations
- In adolescents, depression may manifest primarily as irritability rather than overt low mood; somatic complaints (e.g., fatigue, pain, sleep disturbance) may dominate the presentation. 5
- Avoid over‑reliance on screening instruments; they are adjuncts and should never replace a thorough clinical interview. 5
- Obtain collateral information from teachers, family members, or other observers to capture functional decline that the individual may not self‑report. 5
Emergency Evaluation
- For any individual identified as being at risk of harming self or others, initiate immediate referral to emergency services, ensure one‑to‑one observation, and begin harm‑reduction interventions. [1][2]
Minimum Duration Requirement for Major Depressive Disorder Diagnosis
Core Diagnostic Duration Criterion
- The Diagnostic and Statistical Manual of Mental Disorders (DSM‑5) specifies that depressive symptoms must be present for at least 2 weeks to meet criteria for major depressive disorder (MDD)【7】.
Symptom Inclusion
- Feelings of worthlessness or excessive/inappropriate guilt are listed among the nine required depressive symptoms for MDD diagnosis【7】.
Evidence on Duration in Young Children
- Studies in preschool‑aged children indicate that those who meet all MDD criteria except the 2‑week duration still display clinically significant depression and have comparable two‑year outcomes to children who meet the full duration requirement【7】.
- Despite this evidence, current clinical guidelines continue to require a minimum 2‑week symptom duration for MDD diagnosis across all age groups【7】.