STUDYING POT'S EFFECTS ON DRIVERS

Researcher Hopes To Pinpoint Drugs' Specific Risks

When Mark Asbridge came across surveys indicating driving under the
influence of drugs such as cannabis has surpassed the rate of driving
under the influence of alcohol, it stirred his interest in exploring
the precise effect of cannabis on drivers.

"People are quite concerned about this issue," says Asbridge, an
assistant professor in the Department of Epidemiology and Community
Health at Dalhousie University.

Cannabis affects drivers differently than alcohol. It distorts the
user's perception of space, rather than slowing down reaction time as
is the case with alcohol, Asbridge said.

"It's the question of risk, and whether we can demonstrate if
cannabis can actually increase the risk of a collision, whether or
not it can impact the severity." Asbridge says John Macdonald,
co-ordinator of the Drug Recognition Program for Nova Scotia, says
use of marijuana has grown in recent years and voiced concern about
the potential ramifications on the road.

"You can do the typical driving functions - switching gears,
steering, breaking, accelerating - but you're unaware of your
environment. When your divided attention ability is diminished by
drugs, you're not quite able to pay attention to the traffic lights,
the crosswalks, or whatever's around you," he said. "It takes away
your ability to pay attention. All drugs, whether it be cannabis or
alcohol, are equal in that way."

Over the next two years, Asbridge and the rest of his team plan to
survey 1,500 people in three different Canadian hospitals, including
the QEII Health Sciences Centre in Halifax, and two more hospitals
located in Toronto.