Table 1:

Participant demographic data

		Controls			Drug-users
		Met/Met	Met/Val	Val/Val	Met/Met	Met/Val	Val/Val
Allele		19	66	41	32	73	41
Gender		M: 11; F: 8	M: 28; F: 38	M:24; F:17	M: 17; F:15	M: 51; F:22	M:30; F:11
Age (mean±SD)		31.4±9.5	29.8±8.5	30.6±7.9	34.1±10.1	34.3±9.0	35.0±10.3
Distribution of Drug use across COMT gene	Nicotine	-	-	-	26	61	33
	Alcohol	-	-	-	19	48	30
	Cocaine	-	-	-	8	26	14
	Marijuana/THC	-	-	-	14	33	21
	Heroin/Opiates	-	-	-	4	9	2
FTND		-	-	-	6.08±1.98	4.80±2.24	4.50±1.80
Initial smoking age		-	-	-	14.58±4.95	15.50±3.68	14.70±4.32
AIM score (i.e., Ethnic data) (mean±SD)	Africa	0.38±0.41	0.38±0.41	0.35±0.41	0.26±0.38	0.41±0.40	0.31±0.38
	Europe	0.52±0.43	0.39±0.42	0.36±0.42	0.56±0.42	0.44±0.43	0.49±0.43
	Middle East	0.05±0.07	0.07±0.12	0.06±0.10	0.06±0.11	0.06±0.11	0.07±0.11
	Asia	0.03±0.03	0.09±0.19	0.12±0.23	0.08±0.16	0.05±0.10	0.05±0.08
	Far East Asia	0.00±0.00	0.06±0.21	0.09±0.26	0.02±0.09	0.02±0.11	0.03±0.15
	Oceania	0.01±0.02	0.01±0.01	0.01±0.02	0.01±0.01	0.01±0.02	0.00±0.00
	America	0.01±0.01	0.01±0.01	0.01±0.04	0.01±0.02	0.01±0.04	0.03±0.10