CHICAGO - Based on diffusion tensor imaging (DTI) brain scans, adolescents who are genetically at risk for schizophrenia may increase that risk with heavy use of marijuana, researchers reported in a presentation Wednesday at the 2005 RSNA conference.
Manzar Ashtari, Ph.D., of Zucker Hillside Hospital in Glen Oaks, New York, presented the results of four small studies that looked at the brains of healthy adolescents, adolescent marijuana users, adolescents with schizophrenia who didn't use marijuana, and adolescents with schizophrenia who did use marijuana.
"We found that marijuana affects areas of the brain that are still developing during adolescence, and these are the same areas that are affected by schizophrenia," Ashtari said.
Nondrug using, healthy adolescents have significant developmental activity in the arcuate fasciculus, which is a bundle of fibers that connects Broca's area in the left frontal lobe and Wernicke's area in the left temporal lobe of the brain.
"In early adolescence, much of this area is still under construction," said Ashtari, who compared scans from 12 healthy early-adolescent males to 12 healthy late-adolescent males.
In scans of 11 schizophrenic patients, "these same areas show damage," Ashtari said. And this damage was again evident in scans from 15 otherwise healthy marijuana smokers and 15 schizophrenics who smoked marijuana. The brain areas affected were involved in "speech development, language interpretation, and higher order functions. These are multitasking neurons that are affected," she said.
Based on the studies, Ashtari suggested that heavy marijuana use could trigger schizophrenia in adolescents who are genetically at risk, but she cautioned that the studies are limited by their small size. "We will need to reproduce these findings," she said.
By M. M. Pennell
AuntMinnie.com contributing writer
December 1, 2005
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Marijuana may change blood flow to brain, February 8, 2005
MRI studies make sense of multifaceted schizophrenia, April 27, 2005
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