OPPORTUNITY MAY BE BEHIND 'GATEWAY DRUG' EFFECT

NEW YORK (Reuters Health) - Researchers have long speculated about whether
using so-called "soft" drugs like marijuana will lead to the use of
"harder," more physically addictive drugs, such as cocaine and heroin.

Now, new research suggests a reason why this progression in drug use might
occur: opportunity.

Based on a survey of US households, Dr. James C. Anthony and a colleague
from Johns Hopkins University in Baltimore, Maryland, determined that
tobacco and alcohol users are more likely to encounter opportunities to try
illegal drugs like marijuana. Furthermore, once faced with the opportunity,
users of tobacco and alcohol are more likely to accept marijuana.

And, the investigators found, people who had used marijuana were more
likely to have opportunities to use cocaine. Among those given the
opportunity to use cocaine, those who had used marijuana in the past were
more likely to accept the drug than those who had never smoked pot.

In an interview with Reuters Health, Anthony recommended that programs
aimed at drug prevention take the factor of opportunity into account.
Classroom-based initiatives tend to focus on resisting opportunities when
they arise, a technique that doesn't target the entire problem, Anthony said.

"These resistance skills do not come into play until kids have the drug
exposure opportunities," he noted. "No one 'just says no' unless the drug
is offered to them."

Anthony and his co-author, Fernando A. Wagner, developed their findings
based on surveys of 44,624 residents of US households between the ages of
12 and 25. The surveys were conducted annually from 1991 to 1994, and
include questions about the first use of drugs, and what types of
drug-taking opportunities were encountered.

The investigators determined that a crucial factor that enables tobacco or
alcohol users to progress to marijuana, and pot smokers to take up cocaine,
is "exposure opportunity."

"This exposure opportunity can occur because kids seek it out, or it can
occur simply because kids are exposed without any effort at all--e.g., when
they are walking down the street, or going to parties where others are
using drugs, or sometimes their parents or caregivers offer the drugs,"
Anthony said.

Anthony emphasized that exposure is not solely due to alcohol or tobacco
users seeking out other drugs, for even when the influence of drug-seeking
is removed, users still progressed to more serious drugs.

This indicates that a certain amount of "active sharing" of drugs within
peer groups is also promoting the stepping-stone progression of use,
Anthony said.

He compared offering a peer cocaine to handing over a gun loaded with one
bullet, and playing Russian roulette; the teen may get shot, or may develop
a life-threatening dependency on cocaine. "The odds of getting badly hurt
with cocaine are at least as bad as the odds of getting hit by the bullet,"
the researcher said.

"We don't stress the sharing of drugs in our prevention programs. We need
to do so," he added.

To combat the problem, parents could try to steer children in early
adolescence towards peer groups--such as church-related groups--in which
they are less likely to encounter drug use later on, Anthony said. Also,
programs aimed at drug prevention could encourage teens to not share their
drug-taking habits with kids who have never become involved in drugs.

SOURCE: American Journal of Epidemiology 2002;155:918-925.