Cognitive functioning in opioid-dependent patients treated with buprenorphine, methadone, and other psychoactive medications: stability and correlates

Table 1 Group demographics in sample I

	Buprenorphine (n = 14)	Methadone (n = 12)	Healthy control (n = 14)	Group comparison p-values
Age (M ± SD)	30 ± 7	31 ± 8	29 ± 10	ns
Sex (female/male)	36%/64%	50%/50%	50%/50%	ns
Intelligence^a (M ± SD)	101 ± 11	98 ± 9	105 ± 8	ns
Education, years	10 ± 2	10 ± 1	13 ± 1	BN & M < HC ***
Main opioid of abuse used within last month at T1 (%)
Buprenorphine	93%	83%?	-	ns ^b
Heroin	7%	17%	-	ns ^b
Days in opioid substitution treatment at test (M ± SD)
T1	21 ± 15	20 ± 14	-	ns ^b
T2	210 ± 20	200 ± 28	-	ns ^b
T3	414 ± 46	405 ± 31	-	ns ^b
Examined in inpatient settings %
T1	21%	25%	-	ns ^b
T2	7%	0%	-	ns ^b
T3	7%	8%	-	ns ^b
Participants with high frequency of use of any substance of abuse ^c %
T1	86%	67%	14%	BN > HC **; M > HC
T2	29%	42%	7%	ns ; ns
T3	36%	33%	7%	ns ; ns
	T2 < T1**	T3 < T1*
	T3 < T1*
Participants with the past month extra doses of any opioid ^d, %
T1	86%	92%	-	ns ^b
T2	29%	33%	-	ns ^b
T3	36%	33%	-	ns ^b
	T2 < T1**	T2 < T1**
	T3 < T1*	T3 < T1**
Participants with the past month nicotine use (daily)
T1	100%	100%	36%	BN & M > HC ***
T2	100%	100%	36%	BN & M > HC ***
T3	100%	93%	29%	BN > HC ; M > HC *

Note. BN = buprenorphine patients, HC = healthy control group, and M = methadone patients.
^a Estimation based on the vocabulary and picture completion subtests of the Wechsler Adult Intelligence Scale - Revised (WAIS-R) [67].
^b Tested only between patient groups.
^c High frequency = three or more days a week. Alcohol use was taken into account if it was at least mean weekly 16 portions (12 g) for females and 24 portions for males or binge drinking occurred on any day.
^d Extra doses of any non-prescribed opioid use during the recent month seen in drugs screens or admitted by the patients.
> = superior than, *** = statistically significant at level p < 0.001. ** = statistically significant at level p < 0.01. * = statistically significant at level p < 0.05.