US MA: Column: Is Gateway Drug Theory Valid?

And I'm sure that's true. Indeed, the Center on Addiction and Substance Abuse at Columbia University confirms that most heroin and crack addicts have smoked marijuana.

But hold on just a minute. The fact that one event preceded another does not necessarily mean that the first caused the second.

Most heroin and crack addicts also drank Coca-Cola and ate Oreos. The first substance they ingested was mother's milk. Or formula. What does any of this prove? Not much. Which is precisely the point. Although the gateway theory intuitively makes some sense, in this case, intuition may mislead us. Drs. Lynn Zimmer and John P. Morgan explain in their recent book, "Marijuana Myths, Marijuana Facts, A Review of the Scientific Evidence," that the gateway theory does not describe cause and effect. Rather, it demonstrates a statistical relationship between a relatively common occurrence - smoking marijuana, which 72 million Americans have done - and an uncommon behavior - use of dangerously addictive drugs.

Most marijuana users, according to Zimmer and Morgan, never use any other illegal drug. The statistics they cite show that less than one percent of people who try marijuana become regular users of cocaine or heroin. Zimmer and Morgan illustrate their point with an analogy. Most motorcyclists rode bicycles, but it does not follow, they say, that "bicycle riding causes motorcycle riding." Nor would we expect "an increase in the former to lead automatically to an increase in the latter." If you wanted to cut down on motorcycle traffic, would you prohibit bicycles?

This is not to imply that drug use - particularly among teenagers - doesn't presage problems. It does. But the gateway theory, as a basis for understanding drug abuse, provides a limited and often erroneous paradigm. The scientific studies show that adult drug abusers, as adolescents, used a lot of drugs. They used the readily available legal ones - caffeine, nicotine, and alcohol. Many of them smoked marijuana and also swallowed stimulants or sedatives.

Some raided an adult's medicine cabinet for pain killers, sleeping medications, or diet pills. Others discovered steroids while training for a sport, speed while studying for exams, and codeine in cough suppressants while suffering through a cold.

A significant number inhaled glue vapors or helium from party balloons and experimented with psychedelics. They stuck God-knows-what-else up their noses, down their throats, or into their veins.

For psychological or physiological reasons they couldn't stop using heroin or cocaine or alcohol. They became addicts. Adults disdain and warn kids about alcoholism and drug abuse. But 80 percent of adults in America drink some alcohol. Alcohol is a drug. Kids know that. Some kids, no matter what we say, are going to try some drugs, too. Way too many, in fact. And way too early. Fifty-four percent of eighth-graders in America have used alcohol, and one in 12 gets drunk at least once a month.

Gateway theorists have at least this much right - anyone, especially a kid, using a lot of drugs is swimming in troubled waters. A recent government study reports that adolescent drug users often commit delinquent acts, exhibit eating disorders, and carry within themselves various psychological problems. No parent wants his or her kids to get involved with drugs, including alcohol. Drugs surely can't do a kid any good.

Most drugs, including alcohol for minors, are illegal. That reality, in and of itself, poses dangers. Kids learn their way around a criminal subculture. They may end up in jail.

Worse yet, drugs can kill. If the alcohol poisoning doesn't prove fatal, the car crash could. If the heroin doesn't kill the kid, the shared needle might. Some adults fear that if we draw distinctions among drugs, we may tempt kids to try the not-as-inherently dangerous ones, the so-called gateway drugs. So we, being well-intentioned, lump drugs together and condemn them all equally. That is a mistake. Our apprehension about drugs should not blind us to the differences in their legality, effect, and addictive potential. Some kids, despite our lessons, will experiment with cigarettes, alcohol and marijuana. Indoctrinating those kids with the notion that there's no difference between alcohol and heroin, marijuana and cocaine perpetrates a lie that is anything but benign. A kid who believes that misinformation easily could pass through the gateway to drug dependence and head down a pathway towards death.