Pubdate: Mon, 02 Sep 2013 Source: Cape Argus (South Africa) Copyright: 2013 Cape Argus. Contact: http://capeargus.co.za/ Details: http://www.mapinc.org/media/2939 Note: Daily Mail DAGGA CAN DAMAGE TEENS' BRAINS FOR LIFE 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. - --- MAP posted-by: Jay Bergstrom