Synonyms: Major depressive disorder

Medical Specialties: Family practice, Geriatrics, Internal medicine, Psychiatry

Clinical Definition

Depression is characterized by a dejected mood and a cluster of other symptoms that persist throughout the majority of each day, in a time span of 2 weeks or more. These symptoms include five or more of the following tendencies: sleep changes, eating and appetite changes, low energy, poor concentration, agitation, slowness, thoughts of worthlessness or guilt and recurrent thoughts of suicide or death.

In Our Own Words

Depression has different meanings; the most relevant definition depends upon context. Some people use depression to refer to “having the blues,” a feeling that is fairly common and may not be part of a larger picture of major depression, a clinical diagnosis.


Major depression is a serious mental health condition, and it may be diagnosed if the depressed, sad mood persists for 2 weeks or longer. The potential symptoms of eating and appetite changes, sleep changes, low energy, poor concentration, agitation/slowness and thoughts of worthlessness or guilt tend to intensify gradually and interfere with normal daily activities.


Depression may be mild, chronic or diagnosed as a major depressive disorder. Serious depression is sometimes also called clinical depression. Treatment options include psychotherapy or talk therapy, antidepressant medication or a combination.

Relevant Conditions
  • Dysthymic disorder
  • Depression of chronic disease
  • Chronic pain
  • Anxiety
Common Types
  • Major depressive disorder
  • Mild depression (subclinical depression)
Side Effects
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  • American Psychological Association. "Depression." Accessed August 2013.
  • Cleveland Clinic. "Depression." Updated August 2013. Accessed August 2013.
  • American Psychiatric Association. "Depression." Accessed August 2013.
  • Centers for Disease Control and Prevention. "Treatment Works: Get Help for Depression and Anxiety." Updated October 2012. Accessed August 2013.
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