Diagnostic Questions for Major Depressive Disorder
Use the PHQ-9's nine questions as your primary diagnostic framework, starting with the two core symptoms of depressed mood and anhedonia, then proceeding to the remaining seven symptoms if either core symptom is present. 1
Initial Screening Questions (PHQ-2)
Begin with these two questions, asking about the past 2 weeks 1, 2:
- "Over the past 2 weeks, how often have you had little interest or pleasure in doing things?" (Anhedonia) 1
- "Over the past 2 weeks, how often have you been feeling down, depressed, or hopeless?" (Depressed mood) 1
If either question scores ≥2 on a 0-3 scale (0=not at all, 1=several days, 2=more than half the days, 3=nearly every day), complete the full assessment. If both score 0-1, the screen is negative 1.
Complete Diagnostic Assessment (Full PHQ-9)
When screening is positive, ask about all nine DSM-IV criteria over the past 2 weeks 3, 2:
Core Symptoms (Already Asked)
- Depressed mood most of the day, nearly every day 4, 2
- Loss of interest or pleasure in usual activities (anhedonia) 4, 2
Additional Symptoms
- "Have you experienced significant weight loss or gain, or changes in appetite?" (≥5% body weight change) 4, 2
- "Have you had trouble sleeping or been sleeping too much?" (Insomnia or hypersomnia) 4, 2
- "Have others noticed you moving or speaking more slowly than usual, or have you felt restless and unable to sit still?" (Psychomotor agitation or retardation) 4, 2
- "Have you felt tired or had little energy?" (Fatigue or loss of energy) 4, 2
- "Have you felt worthless or excessively guilty about things?" (Feelings of worthlessness or inappropriate guilt) 4, 2
- "Have you had difficulty thinking, concentrating, or making decisions?" (Diminished ability to concentrate or indecisiveness) 4, 2
Critical Safety Question (Never Omit)
- "Have you had thoughts that you would be better off dead, or thoughts of hurting yourself in some way?" (Suicidal ideation, plan, or attempt) 1, 4, 2
If any self-harm ideation is endorsed, immediate referral for emergency psychiatric evaluation is required regardless of total score. 1
Diagnostic Criteria
A diagnosis of major depressive disorder requires at least 5 of the 9 symptoms present during the same 2-week period, with at least one being either depressed mood or loss of interest/pleasure. 4, 2 The symptoms must cause clinically significant distress or functional impairment 4.
Functional Impairment Assessment
After symptom assessment, ask:
- "How difficult have these problems made it for you to do your work, take care of things at home, or get along with other people?" 3
This assesses whether symptoms interfere with daily functioning, which is required for diagnosis 4.
Clinical Pearls and Pitfalls
Sleep change and loss of energy are the most common symptoms in major depressive disorder, while psychomotor changes and feelings of worthlessness are least common. 5 However, psychomotor change is actually the best indicator when present 5.
Depressed mood, diminished interest/pleasure, and diminished drive are the most clinically valuable rule-in symptoms. 6 The absence of depressed mood, diminished drive, and loss of energy are the best rule-out indicators 6.
Never skip the suicidal ideation question (item 9)—omitting it artificially lowers scores and misses critical risk information. 1
Rule out medical causes before diagnosing: uncontrolled pain, fatigue, delirium from infection or electrolyte imbalance, thyroid disorders, or medication side effects 3.
The PHQ-9 loses accuracy in patients with cognitive impairment; use alternative assessment methods in this population 1.
For elderly patients, consider using the Geriatric Depression Scale (GDS-15), which focuses on affective symptoms and excludes somatic items that may be confounded by medical illness 3.