Although the elevated risk seen in offspring of alcoholics has often been attributed to the alcoholism diagnosis of the parent, it is clear that significant comorbidity would be expected in these parents. Helzer and Pryzbeck (1985) have shown that alcoholic individuals drawn from community samples have increased odds for having other psychiatric disorders. The present longitudinal studies were designed to reduce comorbidity in the parents of these offspring through selection of only those families where the proband had an alcoholism diagnosis before becoming drug dependent or before developing MDD, so that any comorbidity was secondary. Nevertheless, some comorbidity remains using this selection strategy and this comorbidity appears to influence outcome of offspring.
