Genetic and environmental influences on behavioral disinhibition

Comorbidity among childhood disruptive behavioral disorders is commonly rep orted in both epidemiologic and clinical studies, These problems are also a ssociated with early substance use and other markers of behavioral disinhib ition. Previous twin research has suggested that much of the covariation be tween antisocial behavior and alcohol dependence is due to common genetic i nfluences. Similar results have been reported for conduct problems and hype ractivity, For the present study, an adolescent sample consisting of 172 MZ and 162 DZ twin pairs, recruited through the Colorado Twin Registry and th e Colorado Longitudinal Twin Study were assessed using standardized psychia tric interviews and personality assessments, DSM-IV symptom counts for cond uct disorder and attention deficit hyperactivity disorder, along with a mea sure of substance experimentation and novelty seeking, were used as indices of a latent behavioral disinhibition trait. A confirmatory factor model fi t to individual-level data showed a strong common factor accounting for 16- 42% of the observed variance in each measure, A common pathway model evalua ting the genetic and environmental architecture of the latent phenotype sug gested that behavioral disinhibition is highly heritable (a(2) = 0.84), and is not influenced significantly by shared environmental factors, A residua l correlation between conduct disorder and substance experimentation was ex plained by shared environmental effects, and a residual correlation between attention deficit hyperactivity disorder and novelty seeking was accounted for by genetic dominance, These results suggest that a variety of adolesce nt problem behaviors may share a common underlying genetic risk, Am. J. Med . Genet. (Neuropsychiatr. Genet.) 96:684-695, 2000, (C) 2000 Wiley-Liss, In c.