Effects of frequent marijuana use on brain tissue volume and composition

To investigate CNS effects of frequent marijuana use, brain tissue volume a nd composition were measured using magnetic resonance imaging (MRI) in 18 c urrent, frequent, young adult marijuana users and 13 comparable, non-using controls. Automated image analysis techniques were used to measure global a nd regional brain volumes, including,for most regions, separate measures of gray and white matter. The marijuana users showed no evidence of cerebral atrophy or global or regional changes in tissue volumes. Volumes of ventric ular CSF were not higher in marijuana users than controls, but were, in fac t, lower. There were no clinically significant abnormalities in any subject 's MRI. Sex differences were detected in several global volume measures. Ne uroReport 11:491-496 (C) 2000 Lippincott Williams & Wilkins.