Table 5.

Heritability of Cannabis-Related Phenotypes

Trait	Age (p)	Sex (p)	h2	p
Used cannabis	<0.0001		0.52	<0.0001
Used ≥ 21 times year	<0.0001	0.009	0.31	<0.0001
DSM-IV cannabis dependence	<0.0001	0.048	0.20	<0.0001
Age at first use	<0.0001	<0.0001	0.22	0.002
DSM-IV Symptoms
Emotional/psychological problems	<0.0001	0.131	0.23	<0.0001
Cannabis avoid withdrawal	<0.0001	0.014	0.25	0.0001
Cannabis reduced activities	<0.0001		0.21	<0.0001
Great deal of time using	<0.0001	0.002	0.29	<0.0001
Multiple withdrawal symptoms	<0.0001	0.043	0.26	<0.0001
Tried stop cannabis	<0.0001	0.249	0.23	<0.0001
Want stop cannabis	<0.0001	0.007	0.15	0.002
Tolerance	<0.0001	0.637	0.25	<0.0001
Used more than intended	<0.0001		0.11	0.01
Cannabis Consequences
Cannabis depressed > a day	<0.0001	0.03	0.16	0.0006
Cannabis concentrating > a day	<0.0001		0.19	<0.0001
Cannabis paranoid > a day	<0.0001		0.11	0.008
Cannabis “craving”	<0.0001		0.36	<0.0001
Cannabis nervous during withdrawal	<0.0001	0.28	0.30	<0.0001
Cannabis hallucinations > a day	<0.0001		0.07	0.07