Generalizability of the type A/type B distinction across different psychoactive substances.

Previous research using cluster analysis has found that abusers of both alcohol and cocaine can be categorized into more severe (Type B) and less severe (Type A) subgroups. This article sought to replicate and extend these findings in a sample of 521 inpatients, outpatients, and nontreatment-seeking abusers of alcohol, cocaine, marijuana, and opiates. Cluster analyses of subsamples that met the DSM-IV criteria for dependence or abuse for alcohol, cocaine, marijuana, and opiates found that the Type A/Type B distinction was largely generalizable across drugs. Type As--who consistently accounted for about 60% of all substance abuse and about half of abusers in treatment-scored lower than Type Bs on a variety of substance abuse and psychiatric measures that were administered both at intake and at a 6-month follow-up.