Table 1.

Demographic and substance use characteristics of participants.

	MJ+ALC (n = 36)	Controls (n = 36)
	M (SD) or %	M (SD) or %
Years of age (range 16.3-19.0)	17.9 (0.9)	17.8 (0.8)
Female	27.8 %	27.8 %
Caucasian	61.1 %	62.9 %
Annual household income (thousands)	141.7 (128.3)	115.9 (60.2)
Hollingshead socioeconomic level	28.8 (13.7)	30.4 (16.2)
Parental history of a substance use disorder^*^†	41.7 %	11.4 %
WASI Vocabulary T-score^‡	58.4 (8.7)	58.7 (8.7)
WRAT-3 Reading standard score^§	106.7 (8.0)	109.7 (6.6)
Spielberger State Anxiety T-score	39.5 (6.7)	37.7 (7.0)
Beck Depression Inventory Total	3.2 (3.2)	2.6 (2.7)
Child Behavior Checklist Internalizing T-score	46.1 (10.0)	44.8 (7.9)
Child Behavior Checklist Externalizing T-score	49.7 (9.4)	45.2 (10.3)
Age of first marijuana use^*	13.9 (2.0)	15.4 (1.7) ^‖
Age of first weekly marijuana use	14.7 (3.1)	-
Lifetime marijuana use episodes^**	551.7 (481.2)	1.4 (2.3)
Marijuana use days per month (past 3 months)^**	11.6 (8.4)	0.1 (0.3)
Days between last marijuana use and DTI study^**	52.1 (69.6)	355.4 (330.3) ^‖
Age of first alcohol use^*	13.1 (1.9)	14.6 (1.7) ^‖
Age of first weekly alcohol use	15.5 (1.7)	16.0 ^a
Lifetime alcohol drinks^**	195.3 (152.7)	25.0 (38.6)
Drinks per month (past 3 months)^**	52.9 (52.4)	8.2 (12.4)
Days between last alcohol use and DTI study	43.0 (68.6)	86.9 (118.2) ^‖
Cigarettes per smoking day^*	1.2 (3.8)	0.0 (0.2)
Fagerstrom Test for Nicotine Dependence score^*	0.3 (0.7)	0.0 (0.0)
Lifetime other drug use instances^**	10.5 (11.2)	0.5 (2.2)

P<0.05

^**

P<0.001

^†

Parent with DSM-IV alcohol or drug abuse or dependence

^‡

From Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999)

^§

From Wechsler Wide Range Achievement Test (Wilkinson, 1993)

^‖

For controls with history of any marijuana (n=14) or alcohol (n=12) use

(n=1)

MJ+ALC = Marijuana and alcohol user