Context and Extinction: Mechanisms of Relapse in Drug Self-administration
In a classic paper, Hunt, Barnett, and Branch (1971) examined relapse as a function of time since the end of treatment for heroin, alcohol, and tobacco abuse. The paper summarized data from 84 studies in a graph that showed the percentage of people who continued to abstain from each drug over the 12 months that followed quitting. The three curves were essentially identical. Each showed a steep and negatively accelerated decline to an asymptote of only about 30 percent abstaining after 6 and 12 months. Thus, for each drug, about 70 percent of the users were using the drug again within 6 months of quitting. Relatively recent studies of relapse over time have reported similar curves with similarly high relapse rates (e.g., Hughes, Keely, & Naud, 2004; Kirshenbaum, Olsen, & Bickel, 2009). It is clearly dif®cult for drug users to stay abstinent. A signi®cant challenge to therapy, therefore, is to ®nd ways to prevent relapse and promote long-term behaviour change.