PHQ-9 vs GAD-7
The PHQ-9 and GAD-7 are two of the most widely used mental health screeners. The PHQ-9 screens for depression, while the GAD-7 screens for anxiety — but they overlap more than you might think.
Key differences
The PHQ-9 (Patient Health Questionnaire-9) measures the frequency of depressive symptoms over the past two weeks. It is based directly on the DSM-5 criteria for major depressive disorder. The GAD-7 (Generalized Anxiety Disorder-7) measures the frequency of anxiety symptoms over the same period and is based on the DSM-5 criteria for generalized anxiety disorder.
Although both are brief self-report tools, they target different core experiences: depression is marked by low mood, loss of interest, and hopelessness; anxiety is marked by excessive worry, restlessness, and tension. The PHQ-9 includes a question about suicidal thoughts, which the GAD-7 does not — a critical safety feature.
| Dimension | PHQ-9 | GAD-7 |
|---|---|---|
| What it measures | Depressive symptoms (mood, anhedonia, appetite, etc.) | Anxiety symptoms (worry, restlessness, irritability, etc.) |
| Basis | DSM-5 major depressive disorder criteria | DSM-5 generalized anxiety disorder criteria |
| Best for | Identifying possible depression and tracking severity | Identifying possible anxiety and tracking severity |
| Limitations | Cannot diagnose; may over-identify in medical illness; cultural differences | Cannot diagnose; less specific for other anxiety disorders; may miss somatic anxiety |
| Scoring range | 0–27 (5–9 mild, 10–14 moderate, 15–19 moderately severe, 20+ severe) | 0–21 (5–9 mild, 10–14 moderate, 15+ severe) |
| Time to complete | ~3 minutes | ~2 minutes |
What they have in common
Both tools are self-report questionnaires that ask you to rate how often you’ve been bothered by symptoms over the past two weeks on a 4-point scale (0 = not at all, 3 = nearly every day). They are both validated for primary care and are widely used in research and clinical settings. Neither is a standalone diagnostic instrument — a high score warrants a follow-up clinical interview. They also share similar psychometric properties: the PHQ-9 has a sensitivity of 88% and specificity of 88% for major depression (Kroenke et al., 2001), while the GAD-7 has a sensitivity of 89% and specificity of 82% for generalized anxiety disorder (Spitzer et al., 2006).
Which one should you use
If you feel more low, hopeless, or disinterested in things you once enjoyed, start with the PHQ-9. If you feel more restless, tense, or worried, start with the GAD-7. Many people experience both depression and anxiety — in fact, about 60% of people with depression also have anxiety symptoms (Kessler et al., 2005). In that case, you can take both. There is no harm in doing so, and it provides a fuller picture. Ideally, discuss results with a mental health professional who can interpret them in context. Remember: these are screeners, not diagnoses. They help you start a conversation.
Sources
- Kroenke, K., Spitzer, R. L., & Williams, J. B. (2001). The PHQ-9: validity of a brief depression severity measure. Journal of General Internal Medicine, 16(9), 606–613.
- Spitzer, R. L., Kroenke, K., Williams, J. B., & Löwe, B. (2006). A brief measure for assessing generalized anxiety disorder: the GAD-7. Archives of Internal Medicine, 166(10), 1092–1097.
- Kessler, R. C., Chiu, W. T., Demler, O., & Walters, E. E. (2005). Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication. Archives of General Psychiatry, 62(6), 617–627.
FAQ
Which one is more accurate?
Both are highly accurate for their intended uses. The PHQ-9 has slightly higher specificity for depression, while the GAD-7 is excellent for detecting generalized anxiety. Accuracy depends on what you're screening for. Neither is a substitute for a professional diagnosis.
Can I take both?
Yes, absolutely. Many people take both because depression and anxiety often co-occur. Taking both can give you and your clinician a more complete picture. There are no downsides to doing so.
Which should I start with?
Start with the one that matches your most prominent symptoms: if low mood or loss of interest bothers you most, use the PHQ-9. If worry or tension is the main issue, use the GAD-7. When in doubt, start with the PHQ-9 because it includes a question about suicidal thoughts.