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Mood Disorders

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Bipolar Disorders

Bipolar disorders involve at least one distinct period when a person exhibits manic symptoms. Manic symptoms include any or all of the following:

  • Irritability
  • Feelings of being high
  • Decreased need for sleep
  • Inflated self-esteem or grandiosity
  • Fast and pressured speech
  • Agitation
  • Increased interest in pleasurable activities that have the potential for harmful consequences.

People with bipolar disorders usually also experience major depressive episodes. Men and women are equally likely to suffer from bipolar disorders.

Etiology of Mood Disorders

Researchers believe that many different influences interact to produce mood disorders.

Biological Factors

Biological influences include the following:

  • Genetic predisposition: Twin studies suggest that people can be genetically predisposed to major depressive disorder and bipolar disorders. Concordance rates for both major depressive disorder and bipolar disorders are higher for identical twins than fraternal twins. Genetic factors seem to be implicated more in depression among women than among men.
  • Neurotransmitters: Research shows that the neurotransmitters norepinephrine and serotonin are involved in mood disorders.
  • Brain structure: Some research indicates that people with chronic depression tend to have a smaller hippocampus and amygdala in the brain, perhaps because of an excess of the stress hormone cortisol.
Cognitive Factors

Many researchers have studied the various cognitive factors involved in depression:

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Diagnostic and Statistical Manual of Mental Disorders (DSM-5®) / Edition 5