Pubdate: Tue, 02 Apr 2002
Source: Scotsman (UK)
Website: http://www.scotsman.com/
Contact:  The Scotsman Publications Ltd 2002
Forum: http://www.scotsman.com/
Author: Alastair Dalton, Science Correspondent

CANNABIS USE REDUCES INTELLECT

Heavy cannabis use cuts IQ levels, scientists have discovered in the first 
long-term study of the impact of the drug on intelligence.

Researchers in Canada found that the IQ of people who smoked more than five 
joints a week dropped by four points.

By contrast, lighter users and those who had given up the drug did not 
appear to suffer any intelligence reduction.

Dr Peter Fried, who led the study at Carleton University in Ottawa, said 
the findings had important implications for the government's planned 
reclassification of cannabis in Britain.

David Blunkett, the Home Secretary, has proposed that possession of 
cannabis should no longer be an arrestable offence, with the drug placed in 
the same category as anti-depressants and steroids.

However, Dr Fried, a psychologist at the university, said it was not known 
how long the effects of smoking marijuana lasted, and there could be a 
large variation in the concentration of the drug in joints.

In the Ottawa study, Dr Fried compared the IQ of 70 youngsters aged nine to 
12 before they started smoking marijuana with their scores when aged 17-20.

He said the IQ of 15 heavy users fell by an average 4.1 points, while the 
scores of light users, former users and non-users increased, which was 
attributed to higher intelligence as the youths grew up.

Dr Fried said the average IQ of those studied, 109.1, was four points above 
average for young adults, and if the heavy cannabis users' pre-teen levels 
had not been assessed, they would have appeared to have normal IQ.

Those who gave up cannabis took three months to recover their IQ levels.

Dr Fried said: "IQ is a relatively crude assessment, and just because it is 
not permanently affected, we do not know if attention or memory will recover."

Paul Betts, a Speyside-based anti-drugs campaigner whose daughter, Leah, 
died after taking ecstasy, said the study proved what parents had feared 
for years.

He said: "Most of the calls to our drugs helpline are about cannabis use, 
from youngsters or their relatives concerned about school work suffering."
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