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. Author manuscript; available in PMC: 2013 Apr 23.
Published in final edited form as: Drug Alcohol Depend. 2009 Jul 22;105(0):76–82. doi: 10.1016/j.drugalcdep.2009.06.014

Table 1.

Characteristics (%) of 464 offspring who have ever used cannabis within each latent class assignment.

Class 1, high responder
(n = 182)		 Class 2, positive
responders (n = 131)		 Class 3, mixed/relaxed
(n = 101)		 Class 4, low responder
(n = 50)		 Test of significancea,
p-value
4-Group designb
   Group 1 HG–HE 70.3 62.6 67.3 62.0
   Group 2 HE–LE   9.9   9.2   5.9 14.0 0.50
   Group 3 MG–LE   6.0 13.0 10.9   6.0
   Group 4 LG–LE 13.7 15.3 15.8 18.0
Maternal cannabis abuse/dependence   7.7   9.9 10.9   6.0 0.73
Maternal data missing 16.5 22.1 18.8 30.0 0.20
Age (mean years ± S.D.) 23.1 ± 3.8 23.8 ± 3.7 23.7 ± 3.7 24.3 ± 3.7 0.17
Age first cannabis use (mean years ± S.D.)c 15.4 ± 2.4 15.8 ± 2.7 15.5 ± 2.0 15.4 ± 0.84 0.66
Male 61.5 57.3 42.6 36.0 0.001
White race 81.6 69.8 76.8 77.6 0.12
Paternal household income
   ≤20,999   4.4   8.4   4.0   2.0
   21,000–99,999 78.6 74.8 79.0 80.0 0.66
   >100,000 17.0 16.8 17.0 18.0
Offspring lifetime DSM-IV psychiatric disorders
   Conduct disorder 17.0 13.0 11.9   4.0 0.11
   Major depression 17.6 15.3 14.9 10.0 0.61
   Generalized anxiety disorder   5.0   6.9   3.0   4.0 0.57
   Panic disorder   2.8   3.8   5.0   4.0 0.84
   Social phobia   2.8   1.5   0   2.0 0.39
Offspring drug use and DSM-IV abuse/dependence:
Nicotine dependence 25.0 24.4 16.0 14.3 0.19
Alcohol abuse/dep.
   No diagnosis 39.6 51.9 47.5 52.0
   Abuse 26.4 28.2 30.7 26.0 0.10
   Dependence 34.1 19.9 21.8 22.0
Other non-cannabis illegal drug use (ever) 72.5 51.9 57.4 36.0 <0.0001
Cannabis use (lifetime)
   <6 times 14.8 26.7 32.7 72.0
   6–40 times 23.1 37.4 34.7 10.0 <0.0001
   >40 times 62.1 35.9 32.7 18.0
Cannabis abuse/dep.
   No diagnosis 40.1 67.2 68.3 98.0
   Abuse 39.0 28.2 30.7   2.0 <0.0001
   Dependence 20.9   4.6   1.0   0
a

Tests of significance are ANOVA for continuous variables and chi-square for categorical variables, robust variance estimate adjusted for clustered family data.

b

4-Group design: Group 1—offspring at high genetic (HG) and high environmental (HE) risk because fathers are MZ and DZ twins with DSM-III-R illicit drug dependence, Group 2—offspring at high genetic (HG) and low environmental (LE) risk because fathers are unaffected MZ twins with DSM-III-R illicit drug dependent co-twins, Group 3—offspring at medium genetic (MG) and LE risk because fathers are unaffected DZ with DSM-III-R illicit drug dependent co-twins, Group 4—offspring at low genetic and LE because fathers are unaffected MZ and DZ control pairs.

c

Age of first use available if cannabis used 5 or more times.