Neurophysiological functioning of occasional and heavy cannabis users during THC intoxication
Eef L. Theunissen, Gerold F. Kauert, Stefan W. Toennes, Manfred R. Moeller, Anke Sambeth, Mathieu Blanchard, Johannes G. Ramaekers
Psychopharmacology October 5, 2011 DOI: 10.1007/s00213-011-2479-x via OpenAlex
Summary
Heavy cannabis users develop tolerance to some impairing effects of cannabis, observable both in behavior and in brain electrical activity. In a double-blind, placebo-controlled crossover study, 12 occasional and 12 heavy cannabis users smoked a joint containing either 0 or 500 μg/kg body weight THC. During a divided attention task, THC reduced P100 amplitude in occasional users but not in heavy users, indicating tolerance at the neural level. P300 amplitude decreased in both groups. Performance on the stop signal task was impaired in both groups after THC, while divided attention task performance was impaired only in occasional users. Tolerance was evident in event-related potentials, suggesting it is not solely due to behavioral compensation.
Study at a glance
| Characteristics | Double-blind, placebo-controlled, crossover study Peer reviewed |
|---|---|
| Sample size | 24 |
| Population | Occasional and heavy cannabis users |
| Dose | 500 μg/kg body weight THC |
| Topics | Cannabis |
| Keywords | Delta-9-tetrahydrocannabinol Psychology Dronabinol Crossover study Placebo |
| Citations | 82 |
| Key finding | Heavy cannabis users show tolerance to THC-induced reductions in P100 amplitude and divided attention task performance, while P300 amplitude reductions and stop signal task impairments occur in both groups. |
Abstract
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 Δ9-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.