Finally, we found significant additive genetic, 49%, and unique environmental influences, 51%, contributing to variation in nicotine withdrawal equally in both adolescent and adult smokers. This is the first report, to our knowledge, to provide estimates of heritability of nicotine withdrawal in adolescents, in addition to examining comparable influences in adults. The heritability estimate obtained for the latent class structure of nicotine withdrawal of 49% is virtually identical to the estimate associated with meeting criteria for the DSM-IV NW syndrome previously reported (47%; Pergadia et al., 2006b). Thus, the phenotypic and genetic structure of nicotine withdrawal- whether binary as defined in DSM (American Psychiatric Association, 1994) or multilevel from latent classes- is quite consistent across the adolescent and adult samples of smokers.
