Chunk #34 — Results — Question 1: What Are the Similarities and Differences in the Structure and Etiology of Behavioral Disinhibition at Two Points in Adolescent Development? — Components of behavioral disinhibition
Substance use was more heritable early in adolescence (age 12), with an estimated heritability of 58%, in contrast to 20% in older adolescence (age 17). While a large portion of the variance in substance use at age 17 was due to shared environmental factors (cSU2=.55), the same was not true for the earlier time point, where there was no evidence for shared environmental influences (cSU2=.02). Model fitting results for the conduct disorder composite at age 12 were similar to those for substance use (aCD2=.70, cCD2=.11). However, at age 17, the heritability of conduct disorder was substantially larger (aCD2=.49) than the heritability of substance use. The composite score for problems associated with ADHD was moderately heritable at both ages (aADHD2=.41 at age 12, aADHD2=.51 at age 17), with shared environmental factors accounting for a significant portion of the variance at age 12 only (cADHD2=.38). At both ages, novelty seeking showed significant genetic influences (aNS2=.58 at age 12, aNS2=.28 at age 17), without any influence of shared environment.
