is actually not a single cause of depression but rather a variety of
causes that play hand in hand. There is certainly a genetic element
involved in many depression cases (e.g.: the existence of genetic
pre-dispositions have been shown in twin studies). Many environmental
factors, such as environmental toxins, stress, unhealthy lifestyle,
negative life-events and others also play a major role as cause of
depression. On a biological level changes in hormonal levels, e.g.
during pregnancy and menopause, and certain organic diseases can be
causative. Also, depression is always associated with a change in
neurotransmitter, and or neurotransmitter-receptor activity.
further information on the cause of depression, depression types and
treatments have a look