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Depressive Disorders: Biological Factors

Depressive disorders are characterized by persistent sad, empty, or irritable mood, as well as a variety of cognitive and physical symptoms that together are associated with significant impairment for the individual and represent a leading cause of disability worldwide. Etiological models of depression have identified complex interactions among multiple risk factors at the level of genes, neurobiology, temperament and personality, cognitions, coping and emotion regulation, and the environment. This entry summarizes research on some of the major biological factors that have been implicated in risk for depression.

Genetic Factors

Behavioral geneticists have employed family, twin, and adoption studies to determine the degree to which risk for depression can be attributed to genetic versus environmental factors. Family studies suggest that first-degree relatives of individuals with depression are almost ...

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