NCPA - National Center for Policy Analysis


December 5, 2005

Adolescents who regularly smoke marijuana risk damaging a key brain pathway associated with language development and some predisposed to schizophrenia may contract the illness early, according to research presented at the annual meeting of the Radiological Society of North America (RSNA).

According to researchers at Zucker Hillside Hospital in Glen Oaks, New York:

  • Brain scans revealed microscopic abnormalities in a region of the brain that governs higher aspects of language and listening functions in adolescents who are heavy marijuana smokers.
  • Similar damage to the bundle of fibers, called the arcuate fasciculus, that connect the Broca's area in the left frontal lobe and the Wernicke's area in the left temporal lobe was found in the brains of marijuana smokers and schizophrenics studied.

The researchers scanned the brains of 114 subjects, 26 of whom were selected because they were diagnosed schizophrenics.

  • Of the schizophrenic group, 15 smoked marijuana.
  • Another 15 subjects were nonschizophrenic adolescent male marijuana smokers who were matched against nonsmokers; it was those smokers whose scans showed abnormalities in the language and listening pathway.

The brain's language pathway continues to develop during adolescence and is susceptible to neurotoxins introduced through marijuana use, say researchers.

Roughly 3 million Americans aged 12 and older use marijuana on a daily or almost daily basis, according to the National Institute on Drug Abuse. The researchers say longer-term studies were needed to determine if the brain abnormalities observed in adolescents were permanent or not.

Source: "Heavy marijuana use damages adolescent brains-study," Reuters, November 30, 2005.


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