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Effects of smoking marijuana on focal attention and brain blood flow.

Daniel S O'Leary, Robert I Block, Julie A Koeppel, Susan K Schultz, Vincent A Magnotta, Laura L. Boles Ponto, G Leonard Watkins, Richard D Hichwa

Human psychopharmacology April 2007 DOI: 10.1002/hup.832 (opens in new tab)

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AI-extracted from the abstract
Characteristics Randomized crossover neuroimaging study Peer reviewed
Sample size 12
Population Occasional marijuana users, mean age 23.5 years
Interventions Marijuana Placebo
Topics Cannabis
Key points Smoking marijuana, but not placebo, increased normalized regional cerebral blood flow in orbital frontal cortex, anterior cingulate, temporal pole, insula, and cerebellum, and reduced it in visual and auditory cortices across all three tasks. Marijuana lowered auditory cortex flow relative to placebo but did not alter the normal attention-related asymmetry of temporal lobe blood flow. The authors conclude marijuana has dramatic direct effects on rCBF but causes relatively little change in task-related rCBF patterns.

Abstract

Using an attention task to control cognitive state, we previously found that smoking marijuana changes regional cerebral blood flow (rCBF). The present study measured rCBF during tasks requiring attention to left and right ears in different conditions. Twelve occasional marijuana users (mean age 23.5 years) were imaged with PET using [15O]water after smoking marijuana or placebo cigarettes as they performed a reaction time (RT) baseline task, and a dichotic listening task with attend-right- and attend-left-ear instructions. Smoking marijuana, but not placebo, resulted in increased normalized rCBF in orbital frontal cortex, anterior cingulate, temporal pole, insula, and cerebellum. RCBF was reduced in visual and auditory cortices. These changes occurred in all three tasks and replicated our earlier studies. They appear to reflect the direct effects of marijuana on the brain. Smoking marijuana lowered rCBF in auditory cortices compared to placebo but did not alter the normal pattern of attention-related rCBF asymmetry (i.e., greater rCBF in the temporal lobe contralateral to the direction of attention) that was also observed after placebo. These data indicate that marijuana has dramatic direct effects on rCBF, but causes relatively little change in the normal pattern of task-related rCBF on this auditory focused attention task.

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Acute Effects of a Single, Oral dose of d9-tetrahydrocannabinol (THC) and Cannabidiol (CBD) Administration in Healthy Volunteers Healthy male subjects 2012 Randomized controlled trial n = 16
Modulation of Mediotemporal and Ventrostriatal Function in Humans by Δ9-Tetrahydrocannabinol Healthy, native English-speaking, right-handed men of white race/ethnicity who had used... 2009 Randomized controlled trial n = 15
Cannabidiol (CBD) content in vaporized cannabis does not prevent tetrahydrocannabinol (THC)-induced impairment of driving and cognition Healthy volunteers with a history of light cannabis use 2019 Randomized, double-blind, within-subjects crossover n = 14

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