There is little data documenting structural brain changes as a result of prenatal marijuana exposure. In a recent volumetric MRI study of 10-14 year old children with and without intrauterine exposure to cocaine and other drugs of abuse, cortical gray matter was reduced in the marijuana-exposed children, but he model used was not adjusted for age, gender and other drug exposures35. Another recent study, using DTI to assess frontal white matter development in children with prenatal cocaine exposure, found that intrauterine exposure to both cocaine and marijuana resulted in higher (worse) mean diffusivity than exposure to cocaine alone37. Finally, in a study of adult subjects, initiation of marijuana use prior to age 17 years was associated with reductions in whole brain and percent cortical gray matter volumes and increased percent white matter volume, suggesting the possibility that marijuana exposure during developmentally sensitive periods is required to produce structural CNS alterations122. The limited findings of these studies are paralleled by the general lack of association between marijuana use and structural brain abnormalities in adults123, 124.
