Depression is characterized by a sad, low or irritable mood that affects an individual’s capacity to function.[ Reference 1 ] Depressive disorders are common, yet underdiagnosed and undertreated, mental health conditions that are a cause of impaired quality of life, reduced productivity, and increased mortality in the United States.[ Reference 2 ] The prevalence of individuals with depression in the United States is approximately 8 percent during any two-week period,[ Reference 3 ] but current rates likely underestimate the true occurrence of depressive disorders because many with depression never seek treatment.[ Reference 4 ]

Depression is frequently a recurrent disorder.[ Reference 1 ] Individuals with depression are at increased risk of suicide and depression is a significant independent risk factor for a number of medical conditions including first myocardial infarction and cardiovascular mortality.[ Reference 5 ] There are several depressive disorders, including:[ Reference 1 ]

  • Major depressive disorder

  • Persistent depressive disorder (dysthymia)

  • Premenstrual dysphoric disorder

  • Substance/medication-induced depressive disorder

  • Other less common depressive disorders

Service members returning from combat deployments are at increased risk for developing depression.[ Reference 6 ] Research found that 7-14 percent of service members returning from Operation Enduring Freedom (OEF) and 8-15 percent of service members returning from Operation Iraqi Freedom (OIF) met the screening criteria for major depressive disorder.[ Reference 7 ]


  1. American Psychiatric  Association. (2013). Diagnostic and  statistical manual of mental disorders (5th ed.) Arlington, VA: American  Psychiatric Publishing.

  2.  National Institute of Mental Health (NIMH). (n.d.). NIMH causes  of depression. Retrieved from

  3. Centers for Disease Control. (2015). Depression. Retrieved  from

  4.  National Quality Management Program - Lockheed Martin Federal Healthcare. (2004). Depression: Detection, management, and  comorbidity in the Military Health System. Alexandria, VA: Birch & Davis.

  5. Freedland, K.E. & Carney, R.M. (2008). Depression and medical illness. In I. H. Gotlib & C. L. Hammen (Eds.), Handbook of depression, second edition (pp. 113-141). New York, NY: Guilford Press.

    Management of Major Depressive Disorder Working Group (2016). VA/DoD clinical practice guideline for management of major depressive disorder. Retrieved from

    Stewart, T., Yusim, A., & Desan, P. (2005). Depression as a risk factor for cardiovascular disease. Primary Psychiatry, 12(5), 36-41.

  6. Gadermann, A.M.,  Engel, C.C., Naief, J.A., Nock, M.K., Petukhova, M., Santiago, P.N., Benjamin,  W., Zaslavasky, A.M., & Kessler, R. (2012). Prevalence of DSM-IV major  depression among U.S. military personnel: Meta-analysis and simulation. Military Medicine, 177(8), 47-59. 

    Kessler,  R.C., Heeringa, S.G., Stein, M.B., Colpe, L.J., Fullerton, C.S., Hwang, I.,  Naifeh, J.A., Nock, M.K., Petukhova, M., Sampson, N.A., Schoenbaum, M.,  Zaslavsky, A.M., & Ursano, R. Thirty-day prevalence of DSM-IV mental  disorders among nondeployed soldiers in the US Army: Results from the army  study to assess risk and resilience in servicemembers (Army STARRS). Journal of the American Medical Association  Psychiatry, 71 (5), 504-513.

  7. Hoge, C.W.,  Auchterlonie, J.L., & Milliken C.S. (2006). Mental health problems, use of  mental health services, and attrition from military service after returning  from deployment to Iraq or Afghanistan. Journal  of the American Medical Association, 295(9), 1023-32.

    Hoge,  C.W., Castro, C.A., Messer, S.C., McGurk, D., Cotting, D.I., Koffman, R.L.  (2004). Combat duty in Iraq and Afghanistan, mental health problems, and  barriers to care. New England Journal of  Medicine, 351(1), 13-22.

  8. Trivedi, M.H. (2004). The link between depression and physical symptoms. Primary Care Companion Journal of Clinical Psychiatry, 6(suppl 1), 12–16.

  9.  National  Collaborating Centre for Mental Health (UK). (2010). Depression: The treatment and management of depression in adults  (Updated Edition). Leicester (UK): British Psychological Society. Retrieved  from

  10. U.S. Department of Health and Human Services, National Institutes of Health, National Institute of Mental Health. (2015). Depression (NIH Publication No. 15-3561). Bethesda, MD: U.S. Government Printing Office.

  11. Kendler, K.S. & Gardner, C.O. (2011). A longitudinal etiologic model for symptoms of anxiety and depression in women. Psychological Medicine, 41(10), 2035–2045.

  12. Hoge, C.W., Auchterlonie, J.L., & Milliken C.S. (2006). Mental health problems, use of mental health services, and attrition from military service after returning from deployment to Iraq or Afghanistan. Journal of the American Medical Association, 295(9), 1023-32.

  13. Chapman, D.P., Whitfield, C.L., Felitti, V.J., Dube, S.R., Edwards, V.J., & Anda, R.F. (2004). Adverse childhood experiences and the risk of depressive disorders in adulthood. Journal of Affective Disorders, 82(2), 217-225.

  14. Institute of Medicine. (2014). Preventing psychological disorders in service members and their families. Washington DC: National Academies Press. Retrieved from

  15. Department of Veterans Affairs/Department of Defense. (2016). Understanding Depression: A Resource for Providers and Patients. Retrieved from

  16. Institute of Medicine. (2013). Returning home from Iraq and Afghanistan: Assessment of readjustment needs of veterans, service members, and their families. Washington DC: The National Academies Press.

  17. Sullivan, P.F., Neale, M.C., & Kendler, K.S. (2000). Genetic epidemiology of major depression: review and meta-analysis. American Journal of Psychiatry, 157(10), 1552-1562.

  18. Ravindran, A.V., Smith, A., Cameron, C., Bhatla, R., Cameron, I., Georgescu, T.M., & Hogan, M.J. (2009). Toward a functional neuroanatomy of dysthymia: A functional magnetic resonance imaging study. Journal of Affective Disorders, 119(1-3), 9-15.