Abstract
A review of the literature on multiple drug abuse involving two or more drug categories, where at least one is a nonopiate, nonalcoholic substance (MDA-NONA), revealed that Whites and, to a lesser extent, females are overly represented, disproportionate to their composition in other patterns of drug use. In addition, there is evidence that MDA-NONA abusers are very psychologically disturbed and sociopathically deviant, although it has not been established that their clinical picture is worse than that presented by other drug populations. Theoretical frameworks are presented in an attempt to explain these epidemiological findings.