Preventing growth in amphetamine use: long-term effects of the Midwestern Prevention Project (MPP) from early adolescence to early adulthood.

AIM

The aim of the current study was to examine the long-term effect of an early adolescent substance abuse prevention program on trajectories and initiation of amphetamine use into early adulthood.

DESIGN

Eight middle schools were assigned randomly to a program or control condition. The randomized controlled trial followed participants through 15 waves of data, from ages 11-28 years. This longitudinal study design includes four separate periods of development from early adolescence to early adulthood.

SETTING

The intervention took place in middle schools.

PARTICIPANTS

A total of 1002 adolescents from one large mid-western US city were the participants in the study.

INTERVENTION

The intervention was a multi-component community-based program delivered in early adolescence with a primary emphasis on tobacco, alcohol and marijuana use.

MEASURES

At each wave of data collection participants completed a self-report survey that included questions about life-time amphetamine use.

FINDINGS

Compared to a control group, participants in the Midwestern Prevention Project (MPP) intervention condition had reduced growth (slope) in amphetamine use in emerging adulthood, a lower amphetamine use intercept at the commencement of the early adulthood and delayed amphetamine use initiation.

CONCLUSIONS

The pattern of results suggests that the program worked first to prevent amphetamine use, and then to maintain the preventive effect into adulthood. Study findings suggest that early adolescent substance use prevention programs that focus initially on the 'gateway' drugs have utility for long-term prevention of amphetamine use.