THE DEVELOPMENT OF ALCOHOL AND DRUG-ADDICTION IN AN EXPERIMENTAL ANIMAL

Rats being enabled to choose between ethanol or opiate solutions and water develop a controlled consumption of the drug, later on (6-9 months), they become addicted. Controlled consumption is characterized by an individually stable consumption under constant experimental conditions, by a reversible adaptation to the environmental (in particular the social) situation and to taste and odor of the solutions. Individual predisposition factors interact with the social variables. Addictive behaviour includes a loss of reversibility (drug consumption is extremely enhanced after long periods of forced abstinence) and a loss of control (environment, individual factors and taste do no longer modify drug intake). Addiction is substance-specific and (in the case of ethanol) is accompanied by a qualitative change of the drug's effect after voluntary ingestion. Only voluntary, but not forced intake of alcohol or opiate lead to addiction, consequently a learning process has been involved. ''Dynamic'' phases of drug consumption occur during the first weeks of drug experience and during the transition between controlled consumption and addiction. The latter transition includes a continuous increase of drug intake which is able to override several weeks of drug withdrawal. In addition, social changes also can trigger a persisting increase of drug consumption.