The effects of smoking marijuana on cognition and brain function were assessed with PET using H2 15O. Regional cerebral blood flow (rCBF) was measured in five recreational users before and after smoking a marijuana cigarette, as they repeatedly performed an auditory attention task. Blood flow increased following smoking in a number of paralimbic brain regions (e.g. orbital frontal lobes, insula, temporal poles) and in anterior cingulate and cerebellum. Large reductions in rCBF were observed in temporal lobe regions that are sensitive to auditory attention effects. Brain regions showing increased rCBF may mediate the intoxicating and mood-related effects of smoking marijuana, whereas reduction of task-related rCBF in temporal lobe cortices may account for the impaired cognitive functions associated with acute intoxication.
1Mental Health Clinical Research Center, University of Iowa, 2911JPP, 200 Hawkins Drive, Iowa City, IA 52242
2Department of Anesthesia, University of Iowa College of Medicine, Iowa City, IA 52242, USA
3Department of Psychiatry, University of Iowa College of Medicine, Iowa City, IA 52242, USA
4Department of Radiology, University of Iowa College of Medicine, Iowa City, IA 52242, USA
5Department of Speech Pathology and Audiology, University of Iowa College of Medicine, Iowa City, IA 52242, USA
6Corresponding Author: D. S. O'Leary
Acknowledgements: This research was supported in part by the National Institute of Drug Abuse Grant DA10551 and MHCRC43271.
Received 12 July 2000; accepted 28 September 2000