Both THC and cocaine reduced impulse control accuracy in heavy cannabis users
Single doses of both THC and cocaine reduced impulse control accuracy in heavy cannabis users, though cannabis also impaired motor function while cocaine improved it.
Quick Facts
What This Study Found
In a study of 61 heavy cannabis users with cocaine use history, single doses of THC impaired both psychomotor function and impulse control accuracy. Cocaine had a different pattern: it improved psychomotor speed but still increased errors on impulse control tasks.
Both substances reduced the proficiency of impulse control, meaning participants made more errors even when they felt faster. The psychomotor impairments from THC appeared smaller in magnitude compared to those previously reported in occasional cannabis users, consistent with tolerance development.
The finding that both drugs decreased impulse control proficiency suggests that acute intoxication with either substance may increase the risk of impulsive decision-making, including the decision to use more drugs.
Key Numbers
61 heavy cannabis users participated. THC dose was weight-based. Cocaine dose was 300 mg. THC impaired psychomotor function and increased impulse errors. Cocaine improved psychomotor speed but also increased impulse errors.
How They Did This
Double-blind, placebo-controlled, three-way crossover study. Sixty-one heavy cannabis users with cocaine use history received single doses of cannabis (THC based on body weight), cocaine HCl (300 mg), and placebo in randomized order. Participants completed tests of impulse control and psychomotor function after each condition.
Why This Research Matters
Cannabis and cocaine are among the most commonly used drugs in Europe, and they are frequently used together. Understanding how each substance independently affects impulse control in the same population of heavy users provides insight into patterns of continued use and potential relapse risk.
The Bigger Picture
The finding that both drugs impair impulse control accuracy raises an important point about the cycle of drug use: being under the influence of one substance may reduce the ability to resist using another. This has implications for understanding polysubstance use patterns.
What This Study Doesn't Tell Us
The study included only heavy cannabis users with cocaine experience, so results may not apply to occasional users or cannabis-only users. Single-dose administration may not reflect real-world polydrug use patterns. The crossover design assumed no carryover effects between conditions.
Questions This Raises
- ?Does the combination of THC and cocaine together produce greater impulse control deficits than either alone?
- ?Do the tolerance effects on psychomotor impairment extend to impulse control as well?
- ?How do these acute effects influence real-world drug use decisions?
Trust & Context
- Key Stat:
- Both THC and cocaine reduced impulse control accuracy in heavy users
- Evidence Grade:
- Well-designed placebo-controlled crossover trial, though limited to a specific population of heavy users with polysubstance history.
- Study Age:
- Published in 2013.
- Original Title:
- Single doses of THC and cocaine decrease proficiency of impulse control in heavy cannabis users.
- Published In:
- British journal of pharmacology, 170(7), 1410-20 (2013)
- Authors:
- van Wel, J H P, Kuypers, K P C(4), Theunissen, E L(6), Toennes, S W, Spronk, D B, Verkes, R J, Ramaekers, J G
- Database ID:
- RTHC-00748
Evidence Hierarchy
Participants are randomly assigned to treatment or placebo groups to test cause and effect.
What do these levels mean? →Frequently Asked Questions
Do heavy cannabis users develop tolerance to THC impairment?
This study found that psychomotor impairments from THC appeared smaller in heavy users compared to those previously reported in occasional users, consistent with partial tolerance. However, impulse control was still impaired.
Does cocaine improve or impair brain function?
In this study, cocaine improved psychomotor speed (reaction time) but increased errors on impulse control tasks. The pattern suggests stimulation without improved accuracy, which is a risky combination for decision-making.
Read More on RethinkTHC
- THC-amygdala-anxiety-brain
- anandamide-weed-withdrawal
- cannabinoid-receptors-recovery-time
- cannabis-dependence-physical-psychological-addiction-science
- cannabis-developing-brain-teenagers
- cannabis-perception-vs-evidence-gap
- cannabis-use-disorder-test
- cant-enjoy-anything-without-weed
- cross-addiction-quit-weed-start-drinking
- dopamine-recovery-after-quitting-weed
- endocannabinoid-system-explained-simply
- endocannabinoid-system-withdrawal
- is-weed-addictive
- is-weed-addictive-science
- nervous-system-weed-withdrawal-fight-flight
- quitting-weed-and-alcohol
- rehab-for-weed-addiction-necessary
- signs-of-cannabis-use-disorder
- teen-weed-use-under-18-effects-brain
- thc-brain-withdrawal
- thc-prefrontal-cortex-brain-effects
- weed-cortisol-stress-hormones
- weed-memory-loss-recovery
- weed-motivation-amotivational-syndrome
- weed-nervous-system-effects
- weed-reward-system-brain
- weed-vape-pen-addiction
- being-high-247-brain-body-constant-thc
- optimal-tolerance-break-length-reset-timing
Cite This Study
https://rethinkthc.com/research/RTHC-00748APA
van Wel, J H P; Kuypers, K P C; Theunissen, E L; Toennes, S W; Spronk, D B; Verkes, R J; Ramaekers, J G. (2013). Single doses of THC and cocaine decrease proficiency of impulse control in heavy cannabis users.. British journal of pharmacology, 170(7), 1410-20. https://doi.org/10.1111/bph.12425
MLA
van Wel, J H P, et al. "Single doses of THC and cocaine decrease proficiency of impulse control in heavy cannabis users.." British journal of pharmacology, 2013. https://doi.org/10.1111/bph.12425
RethinkTHC
RethinkTHC Research Database. "Single doses of THC and cocaine decrease proficiency of impu..." RTHC-00748. Retrieved from https://rethinkthc.com/research/van-2013-single-doses-of-thc
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.