A study by the Universidade Federal de Sao Paolo has discovered that teens under the age of 15 who use cannabis could cause long term damage to their cognitive functioning.

The findings, published in the June issue of the British Journal of Psychiatry, found that people who start using cannabis early in life develop poorer motor skills and attention spans compared to those who start using the drug later in life - despite no significant difference in IQs between the test groups.

The study looked at the cannabis use of 104 subjects. Forty-nine of these started using the drug before the age of 15, and 55 after the age of 15. A further group of 44 people, who had never taken the drug, took the tests to act as the control group.

Lead researcher Dr Maria Fontes said: "We found that early-onset, but not late-onset, chronic cannabis users had deficits in their cognitive functioning. We know that adolescence is a period in which the brain appears to be particularly vulnerable to the neurotoxic effects of cannabis.

"Brain imaging studies have shown that the brain before the age of 15 is still developing and maturing, so exposure to cannabis during this period may be more harmful and lead to lower mental flexibility. It is possible people who start to use cannabis at a later age may use different neural networks, and be able to compensate for their cognitive deficits more than people who started using cannabis at an earlier stage of brain development."

Posted by Robert Mair on 1.6.11 Comment on this article by sending it to: penny.hosie@pavpub.com 

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