A woman in her 30s comes to a clinic and says that for several months she has been feeling sad and hopeless and too anxious to concentrate on her work. She is afraid she may lose her job and occasionally has thoughts of suicide. She has gained 15 pounds and feels tired all the time. She has trouble falling asleep and then sleeps through her alarm. Often she finds herself bursting into tears, with her heart pounding. The symptoms began after the breakup of a romance. Her self-esteem has always been low, she says, and she has had previous episodes of depression, usually brought on by a disappointment in love. At times she has taken diet pills and been a heavy drinker, but now she is avoiding drugs and alcohol. She does not improve when given the tricyclic antidepressant imipramine, but most of her symptoms go away in a few weeks when she is switched to phenelzine, a monoamine oxidase inhibitor (MAOI).
Although most people would not find anything unusual or remarkable about this condition, it has been called "atypical depression." Why?