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THE MERCK MANUAL MEDICAL LIBRARY: The Merck Manual of Diagnosis and Therapy
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(For mood disorders in children, see Mental Disorders in Children and Adolescents: Depressive Disorders in children and adolescents.)

Mood disorders are emotional disturbances consisting of prolonged periods of excessive sadness, excessive joyousness, or both. Mood disorders are categorized as depressive or bipolar. Anxiety and related disorders (see Anxiety Disorders) also affect mood.

Sadness and joy (elation) are part of everyday life. Sadness is a universal response to defeat, disappointment, and other discouraging situations. Joy is a universal response to success, achievement, and other encouraging situations. Grief, a form of sadness, is considered a normal emotional response to a loss. Bereavement refers specifically to the emotional response to death of a loved one.

A mood disorder is diagnosed when sadness or elation is overly intense and persistent and is accompanied by a requisite number of other mood disorder symptoms. In such cases, intense sadness is termed depression, and intense elation is termed mania. Depressive disorders are characterized by depression; bipolar disorders are characterized by varying combinations of depression and mania.

Lifetime risk of suicide (see Suicidal Behavior) for people with a depressive disorder is 2 to 15%, depending on severity of the disorder. Risk is further increased in the following cases:

  • At the start of treatment, when psychomotor activity is returning to normal but mood is still dark
  • During mixed bipolar states
  • At personally significant anniversaries
  • By severe anxiety
  • By alcohol and substance use

Other complications include disability ranging from mild to complete inability to function, maintain social interaction, and participate in routine activities; impaired food intake; severe anxiety; alcoholism; and other drug dependencies.

Last full review/revision December 2009 by William Coryell, MD

Content last modified December 2009

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