Heavy pot users were found to have working-memory deficits and associated changes in brain morphology that were consistent with changes found in persons with schizophrenia diagnoses, according to a study published in Schizophrenia Bulletin. "The abuse of popular street drugs, such as marijuana, may have dangerous implications for young people who are developing or have developed mental disorders," says Dr. John Csernansky, an author of the study. "This paper is among the first to reveal that the use of marijuana may contribute to the changes in brain structure that have been associated with having schizophrenia."
Smith, M., Cobia, D., Wang, L., Alpert, K.; Cannabis-Related Working Memory Deficits and Associated Subcortical Morphological Differences in Healthy Individuals and Schizophrenia Subjects. Schizophrenia Bulletin. Online December 15, 2013. doi: 10.1093/schbul/sbt176