Chunk #13 — Epigenesis: The Developmental Cascade of Risk, Heterogeneity of Developmental Course, and Possible Indirect Genetic Effects on the Disinhibition Pathway
of the classes. A similar pattern of developmental heterogeneity has been shown for past-year frequency of marijuana use (Schulenberg et al., 2005). Over the past decade, virtually all of the numerous trajectory class studies of adolescent-to-young-adult problem alcohol and marijuana use have found a high-problem class, along with predictors of class membership that clearly differentiate it from one or more of the lower trajectory classes. Studies of early- to middle-adulthood samples have similarly observed this differentiation well into middle adulthood (Jester et al., 2008; Jacob, Bucholz, Sartor, Howell, & Wood, 2005)
