A prospective longitudinal analysis of opioid and stimulant use in American Indian and First Nations communities.

We describe stages of opioid and psychostimulant use (i.e., onset of use and progression to dependence) over the early life course within Indigenous communities where drug overdose impacts have been most extreme. This community-based participatory research includes 9 waves of survey data collected prior to and during the unfolding of the overdose epidemic in North America (2002-2017) on/near 8 distinct American Indian reservations or First Nation reserves. Substance use (psychostimulants, prescription pain pill misuse, and heroin) was assessed via structured diagnostic interviews. Discrete time survival analysis was used to estimate hazard rates for substance use initiation, dependence, and transitions from first use to dependence. Cumulative probability of lifetime use by age 27 years was 29 % for psychostimulants (e.g., methamphetamine), 35 % for prescription pain pills, and 22 % for heroin. New cases of prescription pain pill misuse peaked in the early 2000s, followed by rapid increases in psychostimulant and heroin use starting around 2008. We found that 37 %-51 % of drug users eventually met criteria for dependence, and progression from use to dependence was typically within one year for this sub-group. Socio-demographic factors were differentially associated with probability of substance use, depending on drug type. Findings highlight the critical need for culturally grounded prevention, harm reduction, and treatment strategies to address substance use inequities in Indigenous communities.