A behavioral economic analysis of polydrug abuse in alcoholics: asymmetrical substitution of alcohol and cocaine

Economic concepts can be used to assess how drug prices affect consumption patterns. Increases in price for a commodity typically result in reductions in consumption. Demand is considered elastic if decreases in consumption a re proportionally greater than increases in price, and inelastic if they ar e proportionally smaller than rises in price. The price of one commodity ca n also affect consumption of others. Commodities can function as substitute s, complements or independents, and these concepts refer to increases, decr eases, or no change in the consumption of one il:em as the price of another increases. This study evaluated the effects of drug prices on hypothetical drug-purchasing decisions in 53 alcohol abusers. Experiments 1, 2, and 3 e xamined how alcohol, cocaine, and Valium prices, respectively, influenced p urchases: of alcohol, cocaine, Valium, heroin, marijuana and nicotine. As p rice of alcohol rose in Experiment 1, alcohol purchases decreased and deman d for alcohol was inelastic. Cocaine was a complement to alcohol, but other drugs purchases were independent of alcohol prices. In Experiment 2, deman d for cocaine was elastic as its price increased. Alcohol was a substitute for cocaine, but other drug purchases did not change significantly. In Expe riment 3, demand for Valium was elastic as its price rose, and all other dr ug purchases were independent of Valium prices. Hypothetical choices were r eliable between and within subjects and associated with urinalysis results and lifetime histories of drug abuse. These results suggest that, among alc ohol abusers, cocaine is a complement to alcohol, but alcohol is a substitu te for cocaine. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.