Depression is a common disorder that involves depressed mood and/or
near-complete loss of interest or pleasure in activities that were
previously enjoyed;somatic (eg, weight change, sleep disturbance) &
cognitive manifestations (eg, difficulty concentrating) are
common.Depression may markedly impair the ability to function at work &
to interact socially;risk of suicide is significant.Depressive disorders
occur at any age but typically develop during the mid-teens, 20s, or
30s.Exact cause of depressive disorders is unknown, but genetic &
environmental factors contribute.Sometimes depressive symptoms are
caused by physical disorders (eg, thyroid or adrenal gland disorders,
benign or malignant brain tumors, stroke, AIDS, Parkinson disease,
multiple sclerosis) or use of certain drugs(eg, corticosteroids, some
beta-blockers, interferon, reserpine, ...). Diagnosis is based on
clinical criteria; physical disorders must be ruled out by clinical
evaluation & selected testing (CBC; electrolyte, TSH, B12 & folate
levels). Treatment involves psychotherapy & usually drugs; SSRIs are
usually tried first, & if they are ineffective, other drugs that affect
serotonin and/or norepinephrine may be tr