Tolerance and cross-tolerance to neurocognitive effects of THC and alcohol in heavy cannabis users

Introduction Previous research has shown that heavy cannabis users develop tolerance to the impairing effects of Δ9-tetrahydrocannabinol (THC) on neurocognitive functions. Animal studies suggest that chronic cannabis consumption may also produce cross-tolerance for the impairing effects of alcohol,...

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Bibliographic Details
Published in:	Psychopharmacologia Vol. 214; no. 2; pp. 391 - 401
Main Authors:	Ramaekers, Johannes G., Theunissen, Eef L., de Brouwer, Marjolein, Toennes, Stefan W., Moeller, Manfred R., Kauert, Gerhold
Format:	Journal Article
Language:	English
Published:	Berlin/Heidelberg Springer-Verlag 01-03-2011 Springer Springer Nature B.V
Subjects:	Administration, Inhalation Administration, Oral Adult Alcohol Alcohol Drinking - adverse effects Alcohol Drinking - psychology Alcohol use Analysis Attention Attention - drug effects Biological and medical sciences Biomedical and Life Sciences Biomedicine Blood Blood levels Cannabinoids Cannabis Central Nervous System Depressants - administration & dosage Central Nervous System Depressants - adverse effects Central Nervous System Depressants - blood Cigarettes Cognition Cognition & reasoning Cognition - drug effects Cross-tolerance Double-Blind Method Drinking behavior Dronabinol - administration & dosage Dronabinol - adverse effects Drug abuse Drug Tolerance Effects Ethanol Ethanol - administration & dosage Ethanol - adverse effects Ethanol - blood Executive Function - drug effects Female Humans Impulsive Behavior Inhibition Male Marijuana Marijuana Abuse - complications Marijuana Abuse - psychology Marijuana Smoking - adverse effects Marijuana Smoking - psychology Medical sciences Motor Activity - drug effects Motor control Motor performance tests Motor task performance Neuropsychological Tests Neurosciences Original Investigation Pharmacology/Toxicology Placebo Effect Psychiatry Psychotropic Drugs - administration & dosage Psychotropic Drugs - adverse effects Tetrahydrocannabinol Time Factors Tobacco Young Adult Tolerance Alcohol Impulsivity Cognition Performance THC Cannabidaceae Alcoholic beverage Cannabis Dicotyledones Angiospermae Spermatophyta Drug of abuse Recreational drug
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Summary:	Introduction Previous research has shown that heavy cannabis users develop tolerance to the impairing effects of Δ9-tetrahydrocannabinol (THC) on neurocognitive functions. Animal studies suggest that chronic cannabis consumption may also produce cross-tolerance for the impairing effects of alcohol, but supportive data in humans is scarce. Purpose The present study was designed to assess tolerance and cross-tolerance to the neurocognitive effects of THC and alcohol in heavy cannabis users. Methods Twenty-one heavy cannabis users participated in a double-blind, placebo-controlled, three-way study. Subjects underwent three alcohol-dosing conditions that were designed to achieve a steady blood alcohol concentration of about 0, 0.5, and 0.7 mg/ml during a 5-h time window. In addition, subjects smoked a THC cigarette (400 μg/kg) at 3 h post-onset of alcohol dosing during every alcohol condition. Performance tests were conducted repeatedly between 0 and 7 h after onset of drinking 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). Results Alcohol significantly impaired critical tracking, divided attention, and stop-signal performance. THC generally did not affect task performance. However, combined effects of THC and alcohol on divided attention were bigger than those by alcohol alone. Conclusion In conclusion, the present study generally confirms that heavy cannabis users develop tolerance to the impairing effects of THC on neurocognitive task performance. Yet, heavy cannabis users did not develop cross-tolerance to the impairing effects of alcohol, and the presence of the latter even selectively potentiated THC effects on measures of divided attention.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0033-3158 1432-2072
DOI:	10.1007/s00213-010-2042-1