IQ BOOSTS SEEN IN SOME LIGHT MARIJUANA USERS

Young adults who smoke small amounts of marijuana - between one and five
joints per week - may temporarily raise their IQs, says a study published
recently in the Canadian Medical Association Journal. However, those in the
study who smoked more than five joints weekly, considered to be heavy
users, saw their average IQ drop by 4.1 points. The light users had an
average IQ increase of 5.8 points.

Researchers compared the IQs of 33 current and former marijuana users with
those of 37 young adults who had not used the drug regularly. All 70 were
part of the Ottawa Prenatal Prospective Study, which began in 1978.

The subjects had taken intelligence quotient tests when they were 9 to 12
years old, before any of them used marijuana.

A similar test was administered when the subjects were between 17 and 20,
at which point about half were current or former marijuana users, and IQ
results were compared with the earlier test.

Nonusers, including those who smoked one joint or less per week, had an IQ
increase averaging 2.6 points. Among those who had stopped using marijuana
for at least three months before the second test, IQ gains averaged 3.5 points.

Of all the variables considered, "only the quantity of current marijuana
use, in terms of the number of joints smoked per week, was negatively
related to change in IQ from preteen to young adult," writes lead
researcher Peter Fried, of the psychology department of Carleton
University, Ottawa.