Adolescent Marijuana Use May Result in Permanent Cognitive Dysfunction, Researchers Say

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A recent report published in the Nature journal Neuropsychopharmacology says that routine adolescent marijuana use may result in permanent brain dysfunction. Researchers at the University of Maryland School of Medicine said that youth who use marijuana on a regular basis may also become more susceptible to severe psychiatric disorders, including schizophrenia.

For 20 days, researchers exposed lab mice to low doses of marijuana’s active ingredients. Prior to the experiment, they examined the mice’s cortical oscillations -- neuron activity patterns that, among those with certain psychiatric disorders, are abnormal.

“In the adult mice exposed to marijuana ingredients in adolescence, we found that cortical oscillations were grossly altered, and they exhibited impaired cognitive abilities,” Sylvina Mullins Raver, of the school’s Department of Anatomy and Neurobiology, told the White Mountain Independent. “The striking finding is that, even though the mice were exposed to very low drug doses, and only for a brief period during adolescence, their brain abnormalities persisted into adulthood.”

In a repeat trial, researchers administered the drug to adult mice, with no prior exposure to marijuana. This time, the cortical oscillations remained normal -- an indication, researchers said, that it is only exposure during adolescence that is likely to lead to irreversible brain dysfunctions.

During adolescence, the frontal parts of the brain begin developing. Researchers suggest that the frontal cortex -- the portion of the brain in charge of executive functions like impulse control and planning -- are more severely affected by drugs during this developmental phase.

“Adolescence is the critical period during which marijuana use can be damaging,” Raver said. “Previous research has shown that children who started using marijuana before the age of 16 are at greater risk of permanent cognitive deficits, and have a significantly higher incidence of psychiatric disorders such as schizophrenia.”

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