Is dependence on one drug associated with dependence on other drugs? The cases of alcohol, caffeine and nicotine

Several studies have correlated the use of one drug with that of another dr ug; however, whether dependence on one drug is associated with dependence o n another drug, independent of any use/use association, is unclear. We aske d 196 randomly-selected subjects the DSM-IV criteria for dependence as appl ied to alcohol, caffeine, and nicotine. Among ever users, the severity of a lcohol vs nicotine dependence ann alcohol vs caffeine dependence was relate d, but tills relationship was weak: (r = .22 & .31). Nicotine ann Caffeine dependence were not correlated These results fail to confirm theories of co mmonality that hypothesize dependence on one drug predisposes to dependence an another drug.