Substance abuse and depression link.

A National Institute of Mental Health (NIMH) study provides compelling evidence of a genetic link between depression and substance abuse disorders. "This means that if someone in your family suffers from severe depression, you and other family members need to be aware that not only are you at risk for developing depression, you also may stand an increased chance of developing a substance abuse disorder," explains Loring J. Ingraham, an NIMH intramural scientist in the Laboratory of Psychology and Psychopathology.

Researchers have been aware for some time that a strong genetic component exists for certain forms of severe depressive illness. They also have known that, if one person in a family has a substance abuse disorder, other relatives are at risk for becoming addicted to alcohol or drugs. Until now, however, scientists have had difficulty separating the influence of genetic from environmental factors when the illnesses occurred together in the same family.

The investigators found that people biologically related to depressed individuals were about twice as likely as relatives of non-depressed people to develop either a depressive or a substance abuse disorder--usually alcoholism. The findings come from a study of 67 people in Scandinavia who were adopted as babies and hospitalized for the treatment of a depressive illness sometime...