“Of all the arguments that have been used to demonize marijuana, few have been more powerful than that of the “gateway effect”: the notion that while marijuana itself may not be especially dangerous, it ineluctably leads to harder drugs like heroin and cocaine…”
“The problem here is that correlation isn’t cause. Hell’s Angels motorcycle gang members are probably more 104 times more likely to have ridden a bicycle as a kid than those who don’t become Hell’s Angels, but that doesn’t mean that riding a two-wheeler is a “gateway” to joining a motorcycle gang. It simply means that most people ride bikes and the kind of people who don’t are highly unlikely to ever ride a motorcycle…”
“Scientists long ago abandoned the idea that marijuana causes users to try other drugs: as far back as 1999, in a report commissioned by Congress to look at the possible dangers of medical marijuana, the Institute of Medicine of the National Academy of Sciences wrote:
Patterns in progression of drug use from adolescence to adulthood are strikingly regular. Because it is the most widely used illicit drug, marijuana is predictably the first illicit drug most people encounter. Not surprisingly, most users of other illicit drugs have used marijuana first. In fact, most drug users begin with alcohol and nicotine before marijuana — usually before they are of legal age.
In the sense that marijuana use typically precedes rather than follows initiation of other illicit drug use, it is indeed a “gateway” drug. But because underage smoking and alcohol use typically precede marijuana use, marijuana is not the most common, and is rarely the first, “gateway” to illicit drug use. There is no conclusive evidence that the drug effects of marijuana are causally linked to the subsequent abuse of other illicit drugs.”
“Since then, numerous other studies have failed to support the gateway idea…”
Read more: http://healthland.time.com/2010/10/29/marijuna-as-a-gateway-drug-the-myth-that-will-not-die/