Table 1. Demographic and substance use characteristics of participants (N = 32).

	M (SD)
Age	27.66 (2.7)
Years of education	12.5 (1.6)
Estimated IQ	104.6 (11.9)
WURS Total Score	36.6 (18.6)
Length of abstinence (Days since last used heroin)	402.5 (223.8)
Years of heroin use	7.1 (2.9)
	n (%)
History of past substance dependence:
- alcohol (%)	0
- cannabis (%)	11 (34.4)
- stimulants (%)	2 (6.3)
- cocaine (%)	1 (3.1)
- sedatives (%)	0 (0)
- hallucinogens (%)	0 (0)

Note. IQ = intelligent quotient, WURS = Wender Utah Rating Scale.