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 drug; however, whether dependence on one drug is associated with dependence on another drug, independent of any use/use association, is unclear. We asked 196 randomly-selected subjects the DSM-IV criteria for dependence as applied to alcohol, caffeine, and nicotine. Among ever users, the severity of alcohol vs nicotine dependence and alcohol vs caffeine dependence was related, but this relationship was weak (r = .22 & .31). Nicotine and caffeine dependence were not correlated. These results fail to confirm theories of commonality that hypothesize dependence on one drug predisposes to dependence on another drug.