. 2021 Aug 27;27(1):624–639. doi: 10.1038/s41380-021-01256-1

Table 2.

Heritability estimates for cocaine use, abuse and addiction from twin studies.

Twin registry	Individuals	Phenotype	Prevalence	Heritability h²	Additive genetic factors a²	Shared environmental factors c²	Unique environmental factors e²	Ref.
Minnesota	94 MZ 94 DZ	CA/CD	1.5–12% CA/CD		0.39 CU males 0.74 CA/CD males 0.42 CA/CD females	0.18 CA/CD males 0.12 CA/CD females	0.08 CA/CD males 0.46 CA/CD females	[22]
Norwegian Institute of Public Health Twin Panel (NIPHTP)	668 MZ 718 DZ	CU	1.8%		0.44	0.33	0.23	[23]
Swedish nationwide registries and healthcare data	1720 MZ 1229 DZ 76,457 sibling pairs	Stimulant abuse (including cocaine)	1.7%		0.64 92% common^a 8% specific^a	0.2 100% common^a	0.16 60% common ^a 40% specific	[28]
Vietnam Era Twin (VET) Registry	1,874 MZ 1,498 DZ	CU and symptoms of CA	14.8% CU	0.43 felt dependent				[25]
Virginia Twin Registry	485 MZ 335 DZ (all females)	CU, CA, and symptoms of CD	14% CU 3.5% CA 2.4% CD		0.39 CU 0.79 CA 0.65 symptoms of CD	0.35 CU 0 CA 0 symptoms of CD	0.26 CU 0.21 CA 0.35 symptoms of CD	[24]
Virginia Twin Registry	708 MZ 409 DZ (all males)	CU, CHU, CA and CD	17% CU 3.5% CUH 5% CA 3% CD		0.61 CU 0.55 CHU 0.32 CA 0.79 CD	0.09 CU 0.23 CHU 0.32 CA 0 CD	0.3 CU 0.22 CHU 0.37 CA 0.21 CD	[27]
Virginia Twin Registry	1408 MZ 984 DZ	CU, CA, CD	17.4% CU 5.3% CA/ CD		0.56 CU (7% specific^a) 0.63 CA/CD	0.14 CU 0 CA/CD	0.1 CU 0 CA/CD	[29]
Virginia Twin Registry	4826 twins	CU	9–29%		0.7	–	0.3	[26]
Virginia Twin Registry	2,817 MZ 2,048 DZ	symptoms of CA and CD	3–4% CA/CD	0.7 2% specific^a				[30]

MZ monozygotic twin pairs, DZ dizygotic twin pairs, CU cocaine use, CHU cocaine heavy use, CA cocaine abuse, CD cocaine dependence

^aCommon/specific refers to factors shared with all drugs of abuse assessed in the study or specific to cocaine/stimulants.