Table 1.

Descriptive statistics for treatment and community subsamples

Demographics	TOTAL N=38		Treatment N=22		Community N=16
	n	%	n	%	n	%
Female	16	42.1	9	40.9	7	43.8
Male	22	57.9	13	59.1	9	56.2
DAT1 genotype
10/10	17	44.7	10	45.5	7	43.8
9 carrier	21	55.3	12	54.5	9	56.2
Baseline	Mean (SD)		Mean (SD)		Mean (SD)
Age	16.6 (1.2)		16.8 (1.2)		16.3 (1.0)
Socio-economic status (Hollingshead, 1975)	2.4 (1.0)		2.6 (1.1)		2.1 (0.8)
WAIS Full Scale IQ	102.7 (13.5)		97.0 (12.3)		110.6 (11.2)**
Planning T score	53.9 (13.1)		60.5 (11.3)		44.8 (9.4)**
Barratt Impulsivity Scale score	69.2 (13.0)		76.0 (11.3)		59.9 (8.6)**
Frequency of substance use (past 6-months)†
Alcohol use	2.7 (2.0)		3.4 (1.9)		1.7 (1.8)**
Marijuana use	3.5 (3.3)		5.5 (2.6)		0.7 (1.6)**
Tobacco use	4.1 (3.6)		5.9 (3.1)		1.5 (2.6)**
	n	%	n	%	n	%
Lifetime DSM-IV alcohol use disorder	15	39.5	14	63.6	1	6.2**
Alcohol Abuse	12	31.6	1	50.0	1	6.2
Alcohol Dependence	3	7.9	3	13.6	0	0.0
Lifetime DSM-IV cannabis use disorder	24	63.2	22	100.0	2	12.5**
Cannabis Abuse	18	47.4	16	72.7	2	12.5
Cannabis Dependence	6	15.8	6	27.3	0	0.0
Lifetime DSM-IV nicotine use disorder	7	18.4	0	0.0	7	31.8*
Lifetime DSM-IV psychopathology
Conduct disorder	11	28.9	11	50.0	0	0.0**
Attention deficit hyperactivity disorder	10	26.3	9	40.9	1	6.3*
Major depression	9	23.7	8	36.4	1	6.3*
White matter volume	Mean (SD)		Mean (SD)		Mean (SD)
Prefrontal volume	7.12 (0.44)		7.01 (0.43)		7.29 (0.41)*
Prefrontal volume (excluding orbitofrontal)	5.72 (0.38)		5.62 (0.36)		5.87 (0.38)*
Orbitofrontal volume	1.40 (0.10)		1.39 (0.10)		1.42 (0.10)
Left hemisphere	0.68 (0.05)		0.68 (0.05)		0.69 (0.06)
Right hemisphere	0.72 (0.05)		0.71 (0.06)		0.73 (0.05)

Notes: Baseline N=38; SD= standard deviation.

^†Frequency coded: 0=never used, 1=no use in the last 6-months, 2=used < once per month, 3= once per month, 4=2–3 times per month, 5=once per week, 6= 2–3 times per week, 7= 4–6 times per week, 8=daily;

^*comparison of treatment vs community p<0.05;

^**p<0.01