Abstract
The present study examined a sample of 205 amphetamine and methamphetamine (A/M) abusers in drug treatment programs across Los Angeles County. Data were collected during face-to-face interviews using a natural history interview instrument. We applied a series of growth curve models to investigate treatment effects on A/M use and criminal involvement during a 36-month period (24 months before and 12 months after the referent treatment admission). The modeling results showed strong concurrent treatment effects in reducing A/M use and criminal involvement (e.g., being in treatment was associated, on average, with a decrease of 4.65 to 5.14 days of A/M use per month and of 1.74 crimes per month). A longer length of cumulative time in treatment (either within single episodes or across multiple episodes) was associated with a lower level of A/M use during the initial month of the 36-month period and with a slower rate of decreased use in subsequent months. Cumulative treatment was not associated with trajectories of the criminal measures. The study findings provide some support for treatment effectiveness in decreasing A/M use among A/M abusers treated in community treatment programs. Longitudinal models allow opportunities to reveal the dynamic relationships between treatment and outcome.
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