Pubdate: Mon, 02 Sep 2013
Source: Cape Argus (South Africa)
Copyright: 2013 Cape Argus.
Note: Daily Mail


TEENAGERS who regularly smoke cannabis suffer long-lasting brain 
damage and are in much greater danger of developing schizophrenia.

US researchers who conducted a study say the drug is particularly 
dangerous for a group of people who have a genetic susceptibility to 
the mental health disorder - and it could be the trigger for it.

Asaf Keller, of the University of Maryland School of Medicine, says 
the results highlight the dangers of teenagers smoking cannabis 
during their formative years.

The study exposed young mice to the active ingredient in marijuana 
for 20 days. It found that their brain activity was impaired, with 
the damage continuing into adulthood.

"Adolescence is the critical period during which marijuana use can be 
damaging," says the study's lead author, Sylvina Mullins Raver, a PhD 
candidate at the University of Maryland.

"We wanted to identify the biological underpinnings and determine 
whether there is a real, permanent health risk to marijuana use."

The scientists began by examining cortical oscillations in mice. 
These are patterns of the activity of neurons in the brain and are 
believed to underlie the brain's functions. They are abnormal in 
schizophrenia and other psychiatric disorders.

The scientists exposed young mice to low doses of the active 
ingredient in marijuana for 20 days and then allowed them to return 
to their siblings and develop normally.

"In the adult mice exposed to marijuana ingredients in adolescence, 
we found cortical oscillations were grossly altered and they 
exhibited impaired cognitive abilities," says Raver.

"We also found impaired cognitive behavioural performance in those 
mice. The striking finding is 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."

The scientists repeated the experiment, giving marijuana to adult 
mice that had never been exposed to it. The findings indicated it was 
only drug exposure during the critical teenage years that impaired 
brain activity.
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