Contrasting Trajectories of Heroin, Cocaine, and Methamphetamine Use

ABSTRACT

Current literature has shown that heroin addiction is characterized by long periods of regular use persisting over the life course, whereas the course of stimulant use is less understood. The current study examined long-term trajectories of drug use for primary heroin, cocaine (crack/powder cocaine), and methamphetamine (meth) users. The analyses used data from five studies that collected longitudinal information using the Natural History Instrument, including 629 primary heroin users, 694 cocaine users, and 474 meth users. Drug use trajectories over the 10 years since initiation demonstrated the persistence of use over time for all three drugs, with heroin use at the highest level (13 to 18 days per month), cocaine at the lowest level (8 to 11 days), and meth in between (approximately 12 days per month). Application of growth mixture models revealed five distinctive groups: Consistently High Use (n = 545), Increasing Use (n = 260), Decreasing Use (n = 254), Moderate Use (n = 638), and Low Use (n = 100). Heroin users were disproportionately overrepresented in the Consistently High Use group and underrepresented in the Low Use group; cocaine and meth users were mostly in the Moderate Use group. Users in the High Use group also had earlier onsets of drug use and crime, longer incarceration durations, and were the least employed. Clinical/service policy and practice need to recognize and adapt to the specific patterns and needs of users of different drugs while being mindful of the stage drug users are at in their life course.

KEYWORDS:

• Trajectory
• heroin
• cocaine
• methamphetamine
• growth mixture model

The authors thank the staff at the UCLA Integrated Substance Abuse Programs for manuscript preparation and Dr. B. Muthen for providing consultation on the application of the growth mixture modeling approach.

Dr. Hser is also supported by a Senior Scientist Award (k05DA017648). This research was supported in part by NIDA grant P30DA016383.

Notes

^aGroup differences among three primary drug types were tested.

^bControlling for project.

∗p < 0.05.

∗∗p < 0.01.

^aGroup differences among five trajectory classes controlling project effect.

∗∗p < 0.01.

∗p < 0.05.