Reducing Heroin Use Did Not Lead to Increased Use of Other Drugs Including Cannabis
A 2-year study of 615 heroin users found that reducing heroin use was associated with reduced use of most other drugs, not increased substitution, though cannabis and alcohol use were unrelated to heroin use changes.
Quick Facts
What This Study Found
Researchers followed 615 heroin users recruited for the Australian Treatment Outcome Study at 3, 12, and 24 months. The proportion reporting weekly heroin use declined significantly at all time points.
Reductions in heroin use were associated with less frequent use of other opioids, cocaine, amphetamine, and benzodiazepines. Alcohol use remained stable throughout. Cannabis and alcohol use were unrelated to changes in heroin use.
Longer periods in residential rehabilitation were associated with declines across all drug classes. Maintenance treatment was associated with declines in other opioid and alcohol use specifically. The study found no evidence for drug substitution, directly challenging the concern that reducing heroin use would push people to other substances.
Key Numbers
615 heroin users followed for 24 months. Weekly heroin use declined at all time points. Use of other opioids, cocaine, amphetamine, and benzodiazepines also declined. Cannabis and alcohol use were unrelated to heroin changes. Residential rehab associated with declines across all drug classes.
How They Did This
Longitudinal cohort study with follow-up at 3, 12, and 24 months. Six hundred fifteen heroin users in New South Wales, Australia. Assessed frequency of use across multiple substance categories at each time point.
Why This Research Matters
The fear that treating one addiction simply shifts people to another substance is a common concern that can discourage treatment-seeking. This study provides evidence against that substitution hypothesis, showing that successful heroin reduction tends to coincide with reduced use of most other substances as well.
The Bigger Picture
The independence of cannabis use from heroin use patterns in this study is notable. It suggests cannabis use among polysubstance users may be driven by different factors than opioid or stimulant use, and that changes in heroin use do not systematically affect cannabis consumption.
What This Study Doesn't Tell Us
Limited to treatment-seeking heroin users in one Australian state, which may not generalize to other populations. Self-reported drug use may underestimate actual consumption. The study cannot determine whether reduced use of other drugs was caused by heroin treatment or by general lifestyle changes associated with treatment engagement.
Questions This Raises
- ?Why were cannabis and alcohol use patterns independent of heroin use changes?
- ?Does the lack of substitution hold for longer follow-up periods and in different treatment settings?
Trust & Context
- Key Stat:
- No evidence for drug substitution: reducing heroin was associated with reducing most other drugs too
- Evidence Grade:
- Longitudinal cohort study with multi-point follow-up and adequate sample size. Unable to establish causation but strong observational evidence.
- Study Age:
- Published in 2006. Subsequent research has generally supported the finding that successful addiction treatment does not typically lead to drug substitution.
- Original Title:
- Reductions in heroin use are not associated with increases in other drug use: 2-year findings from the Australian Treatment Outcome Study.
- Published In:
- Drug and alcohol dependence, 84(2), 201-5 (2006)
- Authors:
- Darke, Shane(2), Williamson, Anna, Ross, Joanne, Teesson, Maree
- Database ID:
- RTHC-00221
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Does quitting heroin make people use more cannabis?
No. In this study, cannabis use was unrelated to changes in heroin use. People who reduced heroin use did not increase their cannabis consumption.
Does treating one addiction just create another?
This study found no evidence for drug substitution. Reducing heroin use was associated with reduced use of most other drugs (opioids, cocaine, amphetamines, benzodiazepines), not increased use.
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Cite This Study
https://rethinkthc.com/research/RTHC-00221APA
Darke, Shane; Williamson, Anna; Ross, Joanne; Teesson, Maree. (2006). Reductions in heroin use are not associated with increases in other drug use: 2-year findings from the Australian Treatment Outcome Study.. Drug and alcohol dependence, 84(2), 201-5.
MLA
Darke, Shane, et al. "Reductions in heroin use are not associated with increases in other drug use: 2-year findings from the Australian Treatment Outcome Study.." Drug and alcohol dependence, 2006.
RethinkTHC
RethinkTHC Research Database. "Reductions in heroin use are not associated with increases i..." RTHC-00221. Retrieved from https://rethinkthc.com/research/darke-2006-reductions-in-heroin-use
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.