There was no difference in age or gender between the groups. There were differences in education and IQ between the groups. IQ and education were correlated (p=.03). Table 1 shows the number of SDI meeting criteria for dependence or abuse. There was considerable variation in duration of abstinence across and within different drugs. Average abstinence from cocaine, alcohol, and amphetamine was 4.7, 3.2, and 2.4 years, respectively.
