When Drug Quality Drops, Users Switch to Alcohol and Other Substances
In a simulated drug market, cannabis demand was sensitive to quality changes, with users switching to alcohol when cannabis quality decreased, while alcohol demand was unaffected by quality.
Quick Facts
What This Study Found
Eighty polydrug users completed a simulated purchasing task where drug prices stayed fixed but perceived quality changed for alcohol, amphetamine, cannabis, cocaine, and ecstasy.
Alcohol demand was "quality inelastic," meaning users kept buying the same amount regardless of quality, and alcohol quality changes didn't affect purchases of other drugs.
Cannabis demand was "quality elastic," meaning purchases dropped as quality decreased, and alcohol substituted for cannabis as its effective unit price rose. Similarly, cocaine demand was quality elastic, with alcohol, cannabis, and ecstasy substituting for it. Ecstasy showed the same pattern, with alcohol and cocaine as substitutes.
The key finding was that drug markets behave like economic markets: when one product becomes less appealing, consumers switch to substitutes rather than simply using less.
Key Numbers
80 polydrug users. Alcohol: quality inelastic. Cannabis: quality elastic, alcohol substitutes. Cocaine: quality elastic, alcohol/cannabis/ecstasy substitute. Ecstasy: quality elastic, alcohol/cocaine substitute.
How They Did This
Cross-sectional behavioral economics study. 80 polydrug users completed questionnaires (DAST-A, SDS, AUDIT, HADS) and a simulated drug purchasing task where price remained fixed but quality varied, effectively changing the unit price.
Why This Research Matters
Understanding how drug users respond to quality changes has direct implications for drug policy. If cannabis quality decreases (through regulation, contamination, or enforcement), users may shift to alcohol or other substances rather than reducing total substance use.
The Bigger Picture
This study applied economic theory to drug markets, demonstrating that substance use decisions follow rational economic patterns. This has implications for drug policy: enforcement that reduces cannabis quality may inadvertently increase alcohol use or use of other drugs.
What This Study Doesn't Tell Us
Simulated purchasing tasks may not reflect real-world behavior. The sample of 80 polydrug users may not represent all drug-using populations. The study examined stated preferences rather than actual purchases.
Questions This Raises
- ?Do real-world drug quality fluctuations produce the substitution patterns predicted by this simulation?
- ?Could regulated cannabis markets with quality standards reduce substitution toward more harmful substances?
Trust & Context
- Key Stat:
- Cannabis demand was quality elastic; users switched to alcohol when quality dropped
- Evidence Grade:
- This is a simulated market study with a modest sample size. While the economic framework is sound, stated preferences in simulations may not predict real behavior.
- Study Age:
- Published in 2008. Behavioral economics of drug use has become a more established research field since then.
- Original Title:
- The effects of perceived quality on the behavioural economics of alcohol, amphetamine, cannabis, cocaine, and ecstasy purchases.
- Published In:
- Drug and alcohol dependence, 94(1-3), 183-90 (2008)
- Authors:
- Cole, Jon C, Goudie, Andrew J, Field, Matt, Loverseed, Anne-Claire, Charlton, Sarah, Sumnall, Harry R
- Database ID:
- RTHC-00306
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
What does "quality elastic" mean?
It means demand changes in response to quality. If cannabis quality drops, users buy less cannabis. "Quality inelastic" (like alcohol in this study) means users keep buying the same amount regardless of quality.
Why does this matter for drug policy?
If cracking down on cannabis quality causes users to switch to alcohol or other drugs, the policy may not reduce overall harm. Understanding substitution patterns helps design policies that actually reduce total substance-related harm.
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Cite This Study
https://rethinkthc.com/research/RTHC-00306APA
Cole, Jon C; Goudie, Andrew J; Field, Matt; Loverseed, Anne-Claire; Charlton, Sarah; Sumnall, Harry R. (2008). The effects of perceived quality on the behavioural economics of alcohol, amphetamine, cannabis, cocaine, and ecstasy purchases.. Drug and alcohol dependence, 94(1-3), 183-90. https://doi.org/10.1016/j.drugalcdep.2007.11.014
MLA
Cole, Jon C, et al. "The effects of perceived quality on the behavioural economics of alcohol, amphetamine, cannabis, cocaine, and ecstasy purchases.." Drug and alcohol dependence, 2008. https://doi.org/10.1016/j.drugalcdep.2007.11.014
RethinkTHC
RethinkTHC Research Database. "The effects of perceived quality on the behavioural economic..." RTHC-00306. Retrieved from https://rethinkthc.com/research/cole-2008-the-effects-of-perceived
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.