depressive Major disorder
Causes and symptoms
Causes
Because MDD is a relatively common mental disorder, researchers have performed a range of
different studies to identify possible underlying causes. Three types of causes are commonly
identified: intrapsychic, environmental, and biological.
INTRAPSYCHIC. Since Sigmund Freud attributed the development of mental disorders to
intrapsychic (occurring inside the mind) conflicts occurring during early childhood, a sizeable
number of theorists have suggested that MDD results from a tendency to internalize negative
events. Cognitive behavioral treatment models assume that a person's interpretation of situations
is responsible for the development of depression rather than the events themselves. Some people
blame themselves for negative experiences while attributing positive outcomes to external
sources; they may tend to feel guilty, undeserving, and eventually depressed. For example, they
may think of their present job as something they obtained by a chance stroke of good luck; at the
same time, they may regard being laid off as something they brought on themselves. When these
patterns of thought become habitual, they lead to a style of coping characterized by a view of
oneself as worthless, and ineffectual, inferior. In some cases, people pick up these patterns of
thinking from their parents or other family members.
Another theory regarding intrapsychic causes attributes depression to so-called "learned
helplessness." This theory grew out of research studies on animal learning, comparing dogs that
were able to escape from mild electric shocks to dogs that could not escape. The researchers
discovered that the dogs who could not escape the mild shocks became passive; later, when they
were put in a situation in which they could escape the shocks, they made no attempt to do so but
simply lay on their stomachs and whimpered. The animals had, in short, learned to be helpless;
they had learned during the first part of the experiment that nothing they had done had any effect
on the shocks. Applied to human beings, this theory holds that people tend to become depressed
when they have had long-term experiences of helplessness as would be the case for abused
children. Later, when the children have become adults, they do not see themselves as grownups
with some control over their lives; they continue to react to setbacks or losses with the same
feelings of helplessness that they had as children, and they become depressed.