Question: Cocaine addicts need the drug to feel pleasure. Perhaps giving them a medication that fights depression will help them stay off cocaine. A three-year study compared an antidepressant called desipramine with lithium (a standard treatment for cocaine addiction) and a placebo (Source: D. M. Barnes, “Breaking the cycle of addiction," Science, 241 (1988), pp. 1029-1030). The subjects were chronic users of cocaine who wanted to break their drug habit. A number of the subjects were randomly assigned to each treatment. Here are the counts of the subjects who relapsed and avoided relapse into cocaine use during the study:

Is there any evidence that relapse behavior differs by treatment?