STUDY BOLSTERS MARIJUANA GATEWAY THEORY

CHICAGO -- A study of Australian twins and marijuana bolsters the fiercely
debated "gateway theory" that pot can lead to harder drugs. The researchers
located 311 sets of same-sex twins in which only one twin had smoked
marijuana before age 17. Early marijuana smokers were found to be up to
five times more likely than their twins to move on to harder drugs.

They were about twice as likely to use opiates, which include heroin, and
five times more likely to use hallucinogens, which include LSD.

Earlier studies on whether marijuana is a gateway drug reached conflicting
conclusions. The impasse has complicated the debate over medical marijuana
and decriminalization of pot.

Because this study involved twins, the findings would suggest that genetics
play a subordinate role in drug use.

The study appeared in Wednesday's Journal of the American Medical
Association and was funded in part by the National Institutes of Health. It
does not answer how marijuana, or cannabis, might lead to harder drugs.

Study participants were age 30 on average when they were asked about their
teenage drug use. They included 136 sets of identical twins, who share the
same genetic makeup.

About 46 percent of the early marijuana users reported that they later
abused or became dependent on marijuana, and 43 percent had become
dependent on alcohol.

Cocaine and other stimulants were the most commonly used harder drugs,
tried by 48 percent of the early marijuana users, compared with 26 percent
of the non-early marijuana users. Hallucinogens were the second most
common, used by 35 percent of the early marijuana twins versus 18 percent
of the others.