What Causes Depression?

As for most mental disorders, research indicates that there is no single cause of depression, but that it results from complex interactions among multiple factors.

Biological factors believed to play an important role in depression include genetic factors, neurophysiological factors, and hormonal factors. Twin and family studies of depression suggest that there is some inherited genetic vulnerability to depression, as the risk of having a depressive disorder is significantly greater in those with biological relatives who have had depression. Research has indicated that certain neurotransmitters--serotonin and norepinephrine--function abnormally and/or are present in abnormal amounts in the brains of people with depression. Evidence also indicates that high levels of cortisol, a hormone which is important in regulating response to stress, are found in people with depressive disorders.

Psychological factors believed to influence the development and maintenance of depressive symptoms include cognitive distortions (negative or pessimistic thoughts or beliefs), poor coping skills, problematic interpersonal relationships, poor social support, and stressful life experiences.