Pubdate: Wed, 16 Jan 2013
Source: Dominion Post, The (New Zealand)
Copyright: 2013 The Dominion Post
Contact:  http://www.stuff.co.nz/dominion-post/
Details: http://www.mapinc.org/media/2550
Author: Nicole Pryor
Page: A2

TEENS WHO SMOKE CANNABIS MAY NOT LOSE IQ POINTS, STUDY SHOWS

YOUNG teenagers who smoke cannabis may not be stunting their 
intellect, says a new study challenging a claim by New Zealand 
scientists last year.

The earlier, and widely praised, Dunedin study found people who 
started smoking cannabis in their teenage years, and kept using it 
for years afterwards, showed an average decline in IQ of eight 
points. It sampled more than 1000 people, comparing their IQs from 
when they were 13 to 38.

The study also found those who started using cannabis after the age 
of 18 did not show the same decline in IQ.

The new study, by the Ragnar Frisch Centre for Economic Research in 
Norway, said the Dunedin research did not take into account hidden factors.

Ole Rogeberg, the scientist behind the Norwegian study, said 
socioeconomic status was one of those factors.

In the simulation model created by Mr Rogeberg, poverty was able to 
reproduce the same IQ change as cannabis exposure.

"This model, too, would predict reduced IQ in so far as heavy, 
persistent, adolescent-onset cannabis use involves a culture and 
norms that raise the risk of dropping out of school, getting 
entangled with crime, and other such behaviours," he said. Because 
early cannabis use was more common for those with poor self-control, 
behavioural problems, and those from poor families, Maori 
participants would be over-represented.

He suggested it was too early to connect cannabis smoking and declining IQ.

Fairfax NZ
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