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Neurocognitive performance during acute THC intoxication in heavy and occasional cannabis users.

Abstract

Performance impairment during Delta(9)-tetrahydrocannabinol (THC) intoxication has been well described in occasional cannabis users. It is less clear whether tolerance develops to the impairing effects of THC in heavy users of cannabis. The aim of the present study was to assess neurocognitive performance during acute THC intoxication in occasional and heavy users. Twenty-four subjects (12 occasional cannabis users and 12 heavy cannabis users) participated in a double-blind, placebo-controlled, two-way mixed model design. Both groups received single doses of THC placebo and 500 microg/kg THC by smoking. Performance tests were conducted at regular intervals between 0 and 8 h after smoking, and included measures of perceptual motor control (critical tracking task), dual task processing (divided attention task), motor inhibition (stop signal task) and cognition (Tower of London). THC significantly impaired performance of occasional cannabis users on critical tracking, divided attention and the stop signal task. THC did not affect the performance of heavy cannabis users except in the stop signal task, i.e. stop reaction time increased, particularly at high THC concentrations. Group comparisons of overall performance in occasional and heavy users did not reveal any persistent performance differences due to residual THC in heavy users. These data indicate that cannabis use history strongly determines the behavioural response to single doses of THC.

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  • Publisher Full Text

    • Authors

    Ramaekers JG, Kauert G, Theunissen EL, Toennes SW, Moeller MR

    Institution

    Department of Neuropsychology and Psychopharmacology, Faculty of Psychology, Maastricht University, Maastricht, The Netherlands. j.ramaekers@psychology.unimaas.nl

    Source

    Journal of psychopharmacology (Oxford, England) 23:3 2009 May pg 266-77

    MeSH

    Adult
    Attention
    Cognition
    Double-Blind Method
    Drug Tolerance
    Female
    Hallucinogens
    Humans
    Male
    Marijuana Abuse
    Marijuana Smoking
    Neuropsychological Tests
    Psychomotor Performance
    Reaction Time
    Tetrahydrocannabinol
    Time Factors
    Young Adult

    Pub Type(s)

    Journal Article
    Randomized Controlled Trial
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    18719045