The estimated cumulative incidence of cocaine use to age 60 y was much lower than for the other drugs, making it difficult to derive a useful “interval of risk,” but the intercohort differences appeared more linear—as can be seen in Figure 2, the distance between curves for adjacent cohorts was fairly consistent. Also clear is the fact that for most cohorts, initiation of cocaine use continued into the third decade of life, flattening after age 30 y. It is unclear whether such a trend would be observed when the youngest cohort reached their thirties (given they have not yet passed that age).
