The present study takes a developmental approach to subgrouping and
examines the trajectories of substance use from early adolescence
through young adulthood among a community sample of 481 individuals.
The patterns of use were examined, subgroups were identified separately
for men and women and for alcohol and marijuana, and psychosocial
predictors and psychopathology outcomes that differentiated the groups
were identified. The results revealed three substantially overlapping
subgroups for both alcohol and marijuana: early onset, late onset, and
nonuser. Although the general patterns of which dependent variables
were related to group were similar for alcohol and marijuana, a closer
examination revealed important subgroup differences. For alcohol use,
the early-onset group was more dysfunctional in terms of predictors and
outcomes whereas the late-onset and nonuser groups were better
adjusted. In contrast, for marijuana, the early- and late-onset groups
were both more dysfunctional than the nonuser group. In a final
analysis, we examined the predictive utility of our developmental
approach to subgrouping compared to a traditional, static approach.This research was supported by NIH National
Research Service Award DA07304 from NIDA, Grant DA05312-10 from NIDA,
NIH General Clinical Research Center Grant M01 RR026202, and a
University of Kentucky Research Challenge Trust Fund Fellowship awarded
to Kate Flory.