Neurophysiological functioning of occasional and heavy cannabis users during THC intoxication

• Published in: Psychopharmacologia Vol. 220; no. 2; pp. 341 - 350
• Main Authors: Theunissen, Eef L., Kauert, Gerold F., Toennes, Stefan W., Moeller, Manfred R., Sambeth, Anke, Blanchard, Mathieu M., Ramaekers, Johannes G.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-03-2012; Springer; Springer Nature B.V
• Subjects: Adult; Attention - drug effects; Attention - physiology; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Brain Waves - drug effects; Brain Waves - physiology; Cannabinoids; Double-Blind Method; Dronabinol - pharmacokinetics; Dronabinol - pharmacology; Drug Tolerance - physiology; Drug use; Evoked Potentials - drug effects; Evoked Potentials - physiology; Female; Humans; Inhibition, Psychological; Male; Marijuana; Marijuana Abuse - physiopathology; Medical sciences; Neuropsychology; Neurosciences; Original Investigation; Pharmacology/Toxicology; Psychiatry; Psychomotor Performance - drug effects; Psychomotor Performance - physiology; Tolerance; Event-related potentials; Cannabinoids; Cognition; Psychomotor performance; Electrophysiology; Cannabidaceae; Psychomotricity; Cannabinoid; Neurophysiology; Cannabis; Evoked potential; Dicotyledones; Angiospermae; Spermatophyta; Poisoning; Drug of abuse; Performance; Event evoked potential; Recreational drug
• ISSN: 0033-3158; 1432-2072
• DOI: 10.1007/s00213-011-2479-x

Rationale
Experienced cannabis users demonstrate tolerance to some of the impairing acute effects of cannabis.
Objectives
The present study investigates whether event-related potentials (ERPs) differ between occasional and heavy cannabis users after acute Δ
9
-tetrahydrocannabinol (THC) administration, as a result of tolerance.
Methods
Twelve occasional and 12 heavy cannabis users participated in a double-blind, placebo-controlled, crossover study. On two separate days, they smoked a joint containing 0 or 500 μg/kg body weight THC. ERPs were measured while subjects performed a divided attention task (DAT) and stop signal task (SST).
Results
In the DAT, THC significantly decreased P100 amplitude in occasional but not in heavy cannabis users. P300 amplitude in the DAT was significantly decreased by THC in both groups. The N200 peak in the SST was not affected by treatment in neither of the groups. Performance in the SST was impaired in both groups after THC treatment, whereas performance in the DAT was impaired by THC only in the occasional users group.
Conclusions
The present study confirms that heavy cannabis users develop tolerance to some of the impairing behavioral effects of cannabis. This tolerance was also evident in the underlying ERPs, suggesting that tolerance demonstrated on performance level is not (completely) due to behavioral compensation.