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."