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Regional cerebral blood flow after marijuana smoking.

R J Mathew, W H Wilson, D F Humphreys, J V Lowe, K E Wiethe

Journal of Cerebral Blood Flow & Metabolism September 1992 DOI: 10.1038/jcbfm.1992.106 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Observational study with placebo comparison Peer reviewed
Sample size 20
Population Physically and mentally healthy male volunteers with a previous history of marijuana exposure, drug-free at the time of study
Interventions Marijuana placebo
Dose two strengths of marijuana (strengths not specified in the abstract)
Duration Measurements before and three times after smoking, with blood sampling over 2 hours
Measures 133Xe inhalation technique for regional CBF, plasma delta 9-tetrahydrocannabinol (THC) levels, rating scales for intoxication and mood, blood pressure, pulse rate, end-tidal carbon dioxide, end-tidal carbon monoxide, forehead skin perfusion
Topics Cannabis
Key findings Marijuana smoking was associated with bilateral increases in cerebral blood flow, maximal at 30 minutes and greatest in the frontal region and right hemisphere, while placebo produced no significant blood flow changes. Blood flow increases correlated with intoxication, plasma THC levels, and pulse rate.

Abstract

Regional CBF was measured with the 133Xe inhalation technique before and thrice after smoking marijuana of two strengths and placebo in 20 physically and mentally healthy male volunteers with a previous history of exposure to marijuana. They were drug-free at the time of the study. Blood pressure, pulse rate, end-tidal carbon dioxide, end-tidal carbon monoxide, and forehead skin perfusion were quantified during the CBF measurements. Blood samples were drawn for quantification of plasma levels of delta 9-tetrahydrocannabinol (THC) before and during the 2 h after smoking marijuana or placebo. Drug-induced intoxication and changes in mood were quantified with rating scales. Marijuana smoking was associated with bilateral CBF increase, which was maximal 30 min later. Greater CBF increases were seen in the frontal region and right hemisphere. No significant CBF changes were seen after placebo. Pulse rate and respiration increased significantly after marijuana but not placebo. Both marijuana and placebo smoking were associated with increased end-tidal carbon monoxide. CBF increase in both hemispheres correlated significantly with degree of intoxication, plasma levels of THC, and pulse rate.

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