ANN ARBOR, MICHIGAN. Dr. Randolph Nesse MD, a psychiatrist at the University of Michigan, presents compelling evidence that minor depression (low mood) may actually be an adaptive condition which helps us avoid larger calamities than the ones that actually caused the depression. Dr. Nesse points out that manifestations of disease can arise either from a defect in the body's machinery or as a defensive mechanism. Examples of defects are jaundice and seizures which have no useful purpose. Pain, nausea, diarrhea, and fever, on the other hand, are useful defense mechanisms. He believes that, while major depression may well involve a defect, many cases of minor depression or low mood are actually defense mechanisms. Low mood tends to be accompanied by pessimism and lack of motivation. This may prove to be an advantage when it would be futile to try to correct the situation which gave rise to the depression in the first place. For instance, it may be better to do nothing than to challenge authority; it may be better to "lie low" if efforts to pursue an unreachable goal is likely to result in bodily damage, danger or at best, wasted effort. In the case of marital problems it may be better, at least for a while, to do nothing rather than to rush into a divorce.
Dr. Nesse also suggests that low mood is largely caused by a mismatch between
achievements and expectations. It is therefore not surprising that minor depression is
common among people who are anxious, duty-bound, ambitious, or lacking alternatives.
Such people are often unable to disengage from unreachable goals and low mood may
help them do so. Just as anxiety inhibits us from engaging in dangerous actions so minor
depression may inhibit us from engaging in or continuing futile actions.