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Neurophysiological functioning of occasional and heavy cannabis users during THC intoxication.

Theunissen EL, Kauert GF, Toennes SW, Moeller MR, Sambeth A, Blanchard MM, Ramaekers JG - Psychopharmacology (Berl.) (2012)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, P.O. Box 616, 6200MD Maastricht, The Netherlands. e.theunissen@maastrichtuniversity.nl

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.

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Related in: MedlinePlus

Grand average ERP showing P100 at Oz for targets in the DAT. The upper panel shows ERPs of experienced users, while the lower panel shows that of occasional users
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Fig1: Grand average ERP showing P100 at Oz for targets in the DAT. The upper panel shows ERPs of experienced users, while the lower panel shows that of occasional users

Mentions: P100 ERP analysis included 11 heavy users and 10 occasional users in the THC condition and all subjects in the placebo condition. Mean (SE) values of the ERPs from the DAT are given in Table 4. ERP P100 amplitude demonstrated a significant effect of stimulus (F1,83 = 6.956, p = 0.01) and THC × cannabis use history interaction (F1,83 = 7.877, p = 0.006). This interaction indicated that the occasional users showed a decrease in P100 amplitude when under the influence of THC, while in the heavy users, P100 increased when given THC compared to placebo (see Figs. 1 and 2). Separate paired-sample t tests showed that the decrease in P100 in occasional users after THC was significantly different from placebo (t(19) = −2,74, p = 0.013), while the increase in heavy users was not (t(21) = 1,74, p = 0.096). No effects were found for P100 latency in the DAT.Table 4


Neurophysiological functioning of occasional and heavy cannabis users during THC intoxication.

Theunissen EL, Kauert GF, Toennes SW, Moeller MR, Sambeth A, Blanchard MM, Ramaekers JG - Psychopharmacology (Berl.) (2012)

Grand average ERP showing P100 at Oz for targets in the DAT. The upper panel shows ERPs of experienced users, while the lower panel shows that of occasional users
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285765&req=5

Fig1: Grand average ERP showing P100 at Oz for targets in the DAT. The upper panel shows ERPs of experienced users, while the lower panel shows that of occasional users
Mentions: P100 ERP analysis included 11 heavy users and 10 occasional users in the THC condition and all subjects in the placebo condition. Mean (SE) values of the ERPs from the DAT are given in Table 4. ERP P100 amplitude demonstrated a significant effect of stimulus (F1,83 = 6.956, p = 0.01) and THC × cannabis use history interaction (F1,83 = 7.877, p = 0.006). This interaction indicated that the occasional users showed a decrease in P100 amplitude when under the influence of THC, while in the heavy users, P100 increased when given THC compared to placebo (see Figs. 1 and 2). Separate paired-sample t tests showed that the decrease in P100 in occasional users after THC was significantly different from placebo (t(19) = −2,74, p = 0.013), while the increase in heavy users was not (t(21) = 1,74, p = 0.096). No effects were found for P100 latency in the DAT.Table 4

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, P.O. Box 616, 6200MD Maastricht, The Netherlands. e.theunissen@maastrichtuniversity.nl

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.

Show MeSH
Related in: MedlinePlus