Pot Can Mimic Brain Changes Seen in Schizophrenia

Rats given a marijuana-like drug showed disrupted communications between brain regions, or 'cognitive chaos'

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TUESDAY, Oct. 25 (HealthDay News) -- Marijuana causes disruptions in concentration and memory similar to those that occur in people with schizophrenia, according to a new study.

U.K. researchers measured the electrical activity from hundreds of neurons in the brains of rats given a drug that mimics the effects of cannabis, the psychoactive ingredient of marijuana.

The effects of the drug on individual brain regions were subtle but the drug completely disrupted the coordinated brain waves across the hippocampus and prefrontal cortex. Both of these brain structures are essential for memory and decision-making and play a key role in schizophrenia.

Due to the "decoupling" of the hippocampus and prefrontal cortex, the rats were unable to make accurate decisions while attempting to find their way through a maze, the University of Bristol researchers said.

"Marijuana abuse is common among sufferers of schizophrenia and recent studies have shown that the psychoactive ingredient of marijuana can induce some symptoms of schizophrenia in healthy volunteers. These findings are therefore important for our understanding of psychiatric diseases, which may arise as a consequence of 'disorchestrated brains' and could be treated by re-tuning brain activity," lead author Matt Jones said in a university news release.

The study appears Oct. 25 in the Journal of Neuroscience.

"These results are an important step forward in our understanding of how rhythmic activity in the brain underlies thought processes in health and disease," study first author Michal Kucewicz said.

More information

The U.S. National Institute on Drug Abuse has more about marijuana.

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