WASHINGTON - Casting doubt on a basic principle of U.S. anti-drug policies,
an independent study concluded on Monday that marijuana use does not lead
teenagers to experiment with hard drugs like heroin or cocaine.

The study by the private, nonprofit RAND Drug Policy Research Center
countered the theory that marijuana acts as a so-called gateway drug to
more harmful narcotics, a key argument against legalizing pot in the United
States.

The researchers did not advocate easing restrictions in marijuana, but
questioned the focus on this substance in U.S. drug control efforts.

"The evidence has seemed so strong in favor of the gateway effect that a
lot of policy-makers and others have taken it for granted the gateway
effect is real. We have shown why this is not necessarily the case," said
Andrew Morral, lead author of the RAND study.

Using data from the National Household Survey on Drug Abuse between 1982
and 1994, the study concluded teenagers who took hard drugs were
predisposed to do so whether they tried marijuana first or not.

"Kids get their first opportunity to use marijuana years before they get
their first exposure to hard drugs," Morral said. "It is possible marijuana
is not a gateway drug. It's just the first thing kids often come across."

Morral said 50 percent of U.S. teenagers had access to marijuana by the age
of 16, while the majority had no exposure to cocaine, heroin or
hallucinogens until they were 20.

He said this four-year gap in exposure to the drugs raised doubts about the
gateway theory espoused by many social scientists, and underpinning many
U.S. anti-drug policies and education campaigns.

The study, published in the British journal Addiction, does not advocate
legalizing or decriminalizing marijuana, which has been linked to
side-effects including short-term memory loss.

But given limited resources, Morral said the U.S. government should
reconsider the prominence of marijuana in its much-publicized "war on drugs."

"If our model is correct, to a certain extent we are diverting resources
away from hard drug problems," he said. "Spending money on marijuana
control may not be having downstream consequences on the use of hard
drugs." Researchers say predisposition to drug use has been linked to
genetic factors and one's environment, including family dynamics and the
availability of drugs in the neighborhood.