Current Population Health Topic


Many organizations across the nation are drawing attention to the various—and often surprising—ways mental illness affects people’s lives.

A number of new research findings highlight the need for increased understanding of, empathy for, and respect of people facing mental health issues. Consider the following: Mental Illness is ‘Normal’.

  • People with mental health issues have long felt that they are different from others. Indeed, discussions of mental illness tend to speak about “people with mental illness” as if they are a foreign group few of us ever encounter.
  • The reality is that mental illness is so common—so common, in fact, that a recent study claims that it’s a life unmarred by mental illness that’s the real anomaly.
  • According to the study, which followed people ages 11-38 and tracked their mental health, a mere 17% avoided mental illness.
  • Forty-one percent had a mental health condition that lasted for many years.
  • Forty-two percent had a short-lived mental illness.
  • This suggests that, sooner or later, mental illness becomes an issue for most people.
  • Depression, anxiety, and substance abuse were the most common diagnoses in the study.

A 2005 Cochrane review found that routine depression screening had minimal effect on the management or outcomes of depression after six or 12 months of follow-up. However, the U.S. Preventive Services Task Force (USPSTF) has published more recent reviews on depression screening. This article focuses on the recommendations and findings of the USPSTF.

  • The USPSTF found good evidence that treatment with antidepressants, psychotherapy, or both decreases clinical morbidity and improves outcomes in adults with depression identified through screening in primary care settings.
  • Screening adults for depression is recommended in clinical practices that have systems in place to ensure accurate diagnosis, effective treatment, and follow-up.
  • Screening for depression in clinical practices without these systems is of minimal benefit.
  • Furthermore, the USPSTF found no evidence of harms of screening for depression in adults.
  • The USPSTF found insufficient evidence to recommend for or against screening for suicide risk in the general population, compared with screening only those with depression.
  • The USPSTF recommends screening adolescents 12 to 18 years of age for depression in clinical practices that have systems (or referral systems) in place to ensure accurate diagnosis, psychotherapy (cognitive behavioral or interpersonal therapy), and follow-up.
  • There is insufficient evidence to balance the benefits and harms of depression screening in children seven to 11 years of age.
  • There is adequate evidence that treatment with selective serotonin reuptake inhibitors, psychotherapy, or both decreases depression symptoms in adolescents.
  • Similar evidence is lacking in children.

Many instruments have been developed for depression screening. Although the USPSTF found little evidence that one is superior, the most practical tool for the clinical setting should be used.  Positive results on a screening test should trigger full diagnostic interviews that use standard diagnostic criteria from the Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV).


Ultrashort screening instruments, such as the Patient Health Questionnaire (PHQ)-2 may rule out, but not definitively diagnose, depression.  However, the PHQ-2, which asks two simple questions about mood and anhedonia, has strengths:

  • It is as effective as longer screening instruments, such as the Beck Depression Inventory or Zung Depression Scale.  
  • The PHQ-2 has been found to be up to 97 percent sensitive and 67 percent specific in adults, with a 38 percent positive predictive value and 93 percent negative predictive value.
  • It is reported to have a 74 percent sensitivity and 75 percent specificity in adolescents. 

Patient Health Questionnaire-2: Screening Instrument for Depression

note: If the patient has a positive response to either question, consider administering the Patient Health Questionnaire-9 or asking the patient more questions about possible depression. For older adults, consider the Patient Health Questionnaire-9 or the 15-item Geriatric Depression Scale. A negative response to both questions is considered a negative result for depressionAdapted from patient health questionnaire (PHQ) screeners.

The PHQ-9 is one of the most common instruments used for depression screening.

  • Although it can be used on its own as a screening test or to monitor treatment, it is increasingly administered for confirmation of a positive PHQ-2 result.
  • The PHQ-9 is valid, takes two to five minutes to complete, and has demonstrated 61 percent sensitivity and 94 percent specificity for mood disorders in adults, and 89.5 percent sensitivity and 77.5 percent specificity in adolescents.

Patient Health Questionnaire-9: Screening Instrument for Depression


Total score Depression severity
1 to 4 Minimal
5 to 9 Mild
10 to 14 Moderate
15 to 19 Moderately severe
20 to 27 Severe

Adapted from patient health questionnaire (PHQ) screeners.


A systematic review of 18 studies evaluating nine screening instruments in patients older than 65 years demonstrated sensitivities of 74 to 100 percent, and specificities of 53 to 98 percent.

  • ​The PHQ-2 has a sensitivity of 100 percent and specificity of 77 percent in these patients, whereas the 30-item and the 15-item Geriatric Depression Scales have a sensitivity of 74 to 100 percent and a specificity of 53 to 98 percent.
  • ​A five-item Geriatric Depression Scale was found to be as effective as the 15-item scale, with 97 percent sensitivity and 85 percent specificity.

Five-Item Geriatric Depression Scale
note: A “no” response to question 1, or a “yes” response to questions 2 through 5 each counts as one point. A score of two or more points is considered a positive screen.

  • The American Geriatrics Society recommends using the PHQ-2 as an initial screening test for depression in older adults. If positive, the 15-item Geriatric Depression Scale or the PHQ-9 is recommended as a follow-up test.

15-Item Geriatric Depression Scale

note:  More than five “yes” answers suggests depression and warrants follow-up.  Additional scoring information from


When screening indicates that depression may be present, the diagnosis should be confirmed with the DSM-IV criteria for depression. The criteria are not significantly different in the forthcoming fifth edition of the DSM.

DSM-IV Criteria for Major Depressive Episode
note: DSM-IV = Diagnostic and Statistical Manual of Mental Disorders, 4th ed.

  • Depressive symptoms that do not meet the DSM-IV criteria for depression may be due to other psychological syndromes, such as dysthymic disorder, cyclothymic disorder, substance abuse, bereavement, or bipolar disorder.
    • It is critical to rule out bipolar disorder as a manifestation of the patient’s depression.
    • The Mood Disorder Questionnaire is a validated screening tool for bipolar disorder.
  • Medical conditions that can mimic depression should also be excluded.
    • Measurement of thyroid-stimulating hormone level should be ordered in patients with signs or symptoms of hypothyroidism.
    • Similarly, a complete blood count is needed to rule out anemia.
    • The American Geriatrics Society recommends measurement of thyroid-stimulating hormone, vitamin B12, calcium, and electrolyte levels; liver and kidney function tests; urinalysis; and complete blood count in older adults with symptoms of depression.
  1. HTTPS://WWW.AAFP.ORG/AFP/2012/0115/P139.HTML
  2. Narrow WE, Rae DS, Robins LN, et al. Revised prevalence estimates of  mental   disorders in the United States: using a clinical significance criterion to reconcile 2 surveys’ estimates. Arch Gen Psychiatry. 2002;59(2):115–123….