Marijuana users show brain parallels to schizophrenics

Heavy use of marijuana may put adolescents who are genetically predisposed to schizophrenia at greater risk of developing the brain disorder, according to a study presented at the 2005 RSNA meeting.

Using diffusion tensor imaging, Manzar Ashtari, Ph.D., and colleagues at Zucker Hillside Hospital in Glen Oaks, NY, studied the brains of groups of adolescents: healthy non-drug users; heavy marijuana smokers; and schizophrenic patients. Researchers examined the arcuate fasciculus, a bundle of fibers connecting Broca's area in the left frontal lobe and Wernicke's area in the left temporal lobe of the brain.

They found that repeated exposure to marijuana was related to abnormalities in the development of this fiber pathway, which is associated with the higher aspects of language and auditory functions.

"Because this language/auditory pathway continues to develop during adolescence, it is most susceptible to the neurotoxins introduced into the body through marijuana use," Ashtari said.

Schizophrenic patients also showed abnormalities similar to those found in marijuana smokers. Researchers concluded that in addition to interfering with normal brain development, heavy marijuana use in adolescents may also lead to an earlier onset of schizophrenia in individuals who are genetically predisposed.