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Genetic Factors
There is a risk for developing depression when
there is a family history of the illness, indicating that a biological
vulnerability may be inherited. The risk is somewhat higher for
those with bipolar disorder. However, not everybody with a family
history develops the illness. In addition, major depression can
occur in people who have had no family members with the illness.
This suggests that additional factors, possibly biochemistry,
environmental stressors, and other psychosocial factors, are involved
in the onset of depression.
Biochemical Factors
Evidence indicates that brain biochemistry is
a significant factor in depressive disorders. It is known, for
example, that individuals with major depressive illness typically
have dysregulation of certain brain chemicals, called neurotransmitters.
Additionally, sleep patterns, which are biochemically influenced,
are typically different in people with depressive disorders. Depression
can be induced or alleviated with certain medications, and some
hormones have mood-altering properties. What is not yet known
is whether the "biochemical disturbances" of depression are of
genetic origin, or are secondary to stress, trauma, physical illness,
or some other environmental condition.
Environmental and Other Stressors
Significant loss, a difficult relationship, financial
problems, or a major change in life pattern have all been cited
as contributors to depressive illness. Sometimes the onset of
depression is associated with acute or chronic physical illness.
In addition, some form of substance abuse disorder occurs in about
one-third of people with any type of depressive disorder.7
Other Psychological and Social Factors
Persons with certain characteristics-pessimistic
thinking, low self-esteem, a sense of having little control over
life events, and a tendency to worry excessively-are more likely
to develop depression. These attributes may heighten the effect
of stressful events or interfere with taking action to cope with
them or with getting well. Upbringing or sex role expectations
may contribute to the development of these traits. It appears
that negative thinking patterns typically develop in childhood
or adolescence. Some experts have suggested that the traditional
upbringing of girls might foster these traits and may be a factor
in women's higher rate of depression
REFERENCES
7 Regier DA, Farmer ME, Rae DS, Locke
BZ, Keith SJ, Judd LL, and Goodwin FK. Comorbidity of mental disorders
with alcohol and other drug abuse: Results from the epidemiologic
catchment area (ECA) study. Journal of the American Medical
Association, 1993;264:2511-8
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