Single doses of THC and cocaine decrease proficiency of impulse control in heavy cannabis users
Janelle H. P. van Wel, Kim P. C. Kuypers, Eef L. Theunissen, Stefan W. Toennes, Desirée Spronk, Robbert J. Verkes, Johannes G. Ramaekers
British Journal of Pharmacology October 11, 2013 DOI: 10.1111/bph.12425 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Double-blind, placebo-controlled, three-way crossover study Peer reviewed |
|---|---|
| Sample size | 61 |
| Population | Heavy cannabis users with a history of cocaine use |
| Interventions | cocaine HCl (300 mg) placebo |
| Dose | 300 mg cocaine HCl; cannabis dose expressed as THC μg·kg⁻¹ |
| Topics | Cannabis CBD |
| Keywords | Impulsivity Psychomotor learning Neurocognitive Neuropsychology Crossover study Placebo Poison control Effects of cannabis Audiology Cognition Medical emergency |
| Citations | 38 |
| Key points | Single doses of cannabis impair psychomotor function and increase response errors during impulsivity tasks in heavy cannabis users, while single doses of cocaine improve psychomotor function but also increase errors. |
Abstract
Background: AND
Purpose: Cannabis is the most popular drug used in the European Union, closely followed by cocaine. Whereas cannabis impairs neurocognitive function in occasional cannabis users, such impairments appear less prominent in heavy users, possibly as a result of tolerance. The present study was designed to assess whether the impairing effects of Δ(9) -tetrahydrocannabinol (THC) in heavy cannabis users would present in a wide range of neuropsychological functions or selectively affect specific performance domains. We also assessed the acute effects of cocaine on neurocognitive functions of heavy cannabis users. EXPERIMENTAL APPROACH: Heavy cannabis users, who had a history of cocaine use (n = 61), participated in a double-blind, placebo-controlled, three-way crossover study. Subjects received single doses of cocaine HCl (300 mg), cannabis (THC μg·kg(-1) ) and placebo, and completed a number of tests measuring impulse control and psychomotor function. KEY
Results: Single doses of cannabis impaired psychomotor function and increased response errors during impulsivity tasks. Single doses of cocaine improved psychomotor function and decreased response time in impulsivity tasks, but increased errors.
Conclusions: AND
Implications: Heavy cannabis users display impairments in a broad range of neuropsychological domains during THC intoxication. Impairments observed in psychomotor tasks, but not in impulsivity tasks, appeared smaller in magnitude as compared with those previously reported in occasional cannabis users. Heavy cannabis users were sensitive to the stimulating and inhibitory effects of cocaine on psychomotor function and impulsivity respectively. The reduction in proficiency in impulse control may put drug users at increased risk of repeated drug use and addiction.