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| Research article summary (published 21 Jul 2002): |
Cognitive and subjective dose-response effects of acute oral Delta 9-tetrahydrocannabinol (THC) in infrequent cannabis users.
Full Abstract
RATIONALE:
Although some aspects of memory functions are known to be acutely impaired by delta(9)-tetrahydrocannabinol (delta(9)-THC; the main active constituent of marijuana), effects on other aspects of memory are not known and the time course of functional impairments is unclear.
OBJECTIVE:
The present study aimed to detail the acute and residual cognitive effects of delta(9)-THC in infrequent cannabis users.
METHODS:
A balanced, double-blind cross-over design was used to compare the effects of 7.5 mg and 15 mg delta(9)-THC with matched placebo in 15 male volunteers. Participants were assessed pre and 1, 2, 4, 6, 8, 24 and 48 h post-drug.
RESULTS:
Delta(9)-THC 15 mg impaired performance on two explicit memory tasks at the time of peak plasma concentration (2 h post-drug). At the same time point, performance on an implicit memory task was preserved intact. The higher dose of delta(9)-THC resulted in no learning whatsoever occurring over a three-trial selective reminding task at 2 h. Working memory was generally unaffected by delta(9)-THC. In several tasks, delta(9)-THC increased both speed and error rates, reflecting "riskier" speed-accuracy trade-offs. Subjective effects were also most marked at 2 h but often persisted longer, with participants rating themselves as "stoned" for 8 h. Participants experienced a strong drug effect, liked this effect and, until 4 h, wanted more oral delta(9)-THC. No effects of delta(9)-THC were found 24 or 48 h following ingestion indicating that the residual effects of oral delta(9)-THC are minimal.
CONCLUSIONS:
These data demonstrate that oral delta(9)-THC impairs episodic memory and learning in a dose-dependent manner whilst sparing perceptual priming and working memory.
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Author information
Author/s: Curran, H Valerie (HV); Brignell, Catherine (C); Fletcher, Sally (S); Middleton, Paul (P); Henry, John (J);
Affiliation: Psychopharmacology Laboratories, Clinical Health Psychology, University College London, Gower Street, London WC1 6BT, UK. v.curran(-atsign-)ucl.ac.uk
Journal and publication information
Publication Type: Clinical Trial; Comparative Study; Controlled Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't
Journal: Psychopharmacology (Psychopharmacology (Berl)), published in Germany. (Language: eng)
Reference: 2002-Oct; vol 164 (issue 1) : pp 61-70
Dates: Created 2002/10/09; Completed 2003/01/07; Revised 2006/11/15;
PMID: 12373420, status: MEDLINE (last retrieval date: 11/6/2008)
Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.
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