Concurrent and sequential use of drugs and alcohol: patterns, characteristics of users, and implications for treatment and prevention.

A treatment population of 1,544 drug/alcohol abusers at 10 combined treatment centers was studied to determine the various patterns of sequential use and their corresponding policy implications. Most of the persons who began their substance abuse with alcohol continued to use only alcohol. Alcoholics who did use another substance, either sequentially or concurrently, tended to select a drug other than opiates or marijuana. Although a majority of opiate users eventually became concurrent or sequential users of another substance, a sizable number remained mono-users. A miniscule number of the opiate users moved on to alcohol or marijuana. Most of the users initiated into regular use with marijuana eventually began to use a nonopiate, nonalcoholic substance. A majority of the users who started with a nonalcohol, nonopiate, nonmarijuana substance eventually used marijuana. Sequential and concurrent users in general were more similar to each other than to mono-users. The implications of the development of drug use typologies for direct treatment are discussed. Having identified target groups, the author then suggests policies for controlling substance abuse indirectly, such as those dealing with employment.