Table 1. Demographics and Drug Use History.

Background Variable	Control subjects	Chronic MJ users	t	p
Age (years)	24.72±5.25	24.32±3.85	0.39	0.70
Education (years)	15.95±2.104	15.04±2.26	1.83	0.07
ITED—Quantitative	78.03±15.53	73.46±14.50	1.35	0.18
ITED—Expression	83.18±15.52	77.44±18.19	1.48	0.14
MJ use
Years of regular MJ use	0±0	6.26±3.20	−13.13	<0.001
Average days of MJ use per month in past 2 years	0.06±0.16	24.58±6.17	−26.63	<0.001
Frequency of MJ use in past 30 days (days)	0±0	25.87±5.39	−32.21	<0.001
Alcohol use
Years of regular alcohol use	0.62±2.00	1.12±1.64	−1.23	0.22
Frequency of alcohol use in past 30 days (days)	4.53±6.17	6.69±5.80	−1.60	0.11
Tobacco use
Average number of cigarettes per day in past year	0.147±0.54	3.022±5.11	−3.75	<0.001
Other drug use (% of subjects)
Amphetamines	0%	16%		0.004
Barbiturates	0%	0%		—
Cocaine	0%	18%		0.002
Ecstasy	0%	7%		0.17
Hallucinogens	0%	20%		<.001
Heroin	0%	2%		1.00
Inhalants	0%	0%		—
Methadone	0%	0%		—
Other opiates or analgesics	0%	13%		0.02
Other sedatives, hypnotics, and tranquilizers	0%	4%		0.05

Note: ITED=Iowa Tests of Educational Development (values represent normal curve equivalent scores). When variances differed across groups, t-values were based on Satterthwaite adjustment for unequal variances. Other drug use reflects percentage of subjects who reported using a given class of drugs between 10–99 times in their lifetime (p-value is based on Fisher's exact test). No one used other drugs more than 99 times in their lifetime.