Impact of cannabis inhalation on driving skills in occasional smokers


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Inproceedings: an article in a conference proceedings.
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Abstract (Abstract): shot summary in a article that contain essentials elements presented during a scientific conference, lecture or from a poster.
Impact of cannabis inhalation on driving skills in occasional smokers
Title of the conference
Tri-Annual Meeting of the International Council on Alcohol, Drugs and Traffic Safety
Thomas A., Battistella G., Maeder P., Mall J.F., Annoni J.M., Chtioui H., Appenzeller M., Buclin T., Staub C., Mangin P., Favrat B., Fornari E., Giroud C.
Oslo, Norway, August 22-26, 2010
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Objectives: Our aim was to study the brain regions involved in a divided attention tracking task related to driving in
occasional cannabis smokers. In addition we assessed the relationship between THC levels in whole blood
and changes in brain activity, behavioural and psychomotor performances.
Methods: Twenty-one smokers participated to two independent cross-over fMRI experiments before and after
smoking cannabis and a placebo. The paradigm was based on a visuo-motor tracking task, alternating active
tracking blocks with passive tracking viewing and rest condition. Half of the active tracking conditions
included randomly presented traffic lights as distractors.
Blood samples were taken at regular intervals to determine the time-profiles of the major cannabinoids.
Their levels during the fMRI experiments were interpolated from concentrations measured by GCMS/
MS just before and after brain imaging.
Results: Behavioural data, such as the discard between target and cursor, the time of correct tracking and the reaction
time during traffic lights appearance showed a statistical significant impairment of subject s skills
due to THC intoxication. Highest THC blood concentrations were measured soon after smoking and ranged between 28.8 and 167.9
ng/ml. These concentrations reached values of a few ng/ml during the fMRI.
fMRI results pointed out that under the effect of THC, high order visual areas (V3d) and Intraparietal sulcus
(IPS) showed an higher activation compared to the control condition. The opposite comparison showed
a decrease of activation during the THC condition in the anterior cingulate gyrus and orbitofrontal
areas. In these locations, the BOLD showed a negative correlation with the THC level.
Conclusion: Acute cannabis smoking significantly impairs performances and brain activity during active tracking
tasks, partly reorganizing the recruitment of brain areas of the attention network. Neural activity in the
anterior cingulate might be responsible of the changes in the cognitive controls required in our divided attention
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24/02/2011 13:52
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20/08/2019 14:42
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