Objectives: We examined disparities in age-related patterns of marijuana initiation in 2 culturally distinct American Indian reservation communities (from the Northern Plains and the Southwest) compared with a national sample.
Methods: We used discrete-time survival models to estimate age-related risk for initiation with data from 2 population-based studies: the American Indian Service Utilization, Psychiatric Epidemiology, Risk and Protective Factors Project and the baseline National Comorbidity Survey.
Results: Among respondents who were born before 1960, peak risk for marijuana initiation in all samples was at age 18 years, and risk was greatest in the national sample. Among those who were born later than 1960, risk peaked at age 16 years and was highest in the American Indian samples. Males were at increased risk compared with females, especially in the older cohort and the Southwest tribal sample.
Conclusions: Findings of disproportionate risk for marijuana initiation among younger members of the tribal samples raise concerns that American Indian reservation youths may be increasingly vulnerable to drug use and its concomitants, which suggests a need for more aggressive prevention efforts in these communities.