Is marijuana a "gateway" or "stepping stone" drug?
General Reference (not clearly pro or con)
The Institute of Medicine published in its Mar. 1999 report titled "Marijuana and Medicine: Assessing the Science Base":
"The gateway analogy evokes two ideas that are often confused. The first, more often referred to as the 'stepping stone' hypothesis, is the idea that progression from marijuana to other drugs arises from pharmacological properties of marijuana itself.
The second is that marijuana serves as a gateway to the world of illegal drugs in which youths have greater opportunity and are under greater social pressure to try other illegal drugs."
Is marijuana a "gateway" or "stepping stone" drug?
The Journal of the American Medical Association (JAMA) reported on a study of 311 young adult twin pairs conducted by Michael T. Lynskey, PhD, in its Jan. 22, 2003 issue:
Individuals who used cannabis by age 17 years had odds of other drug use, alcohol dependence, and drug abuse/dependence that were 2.1 to 5.2 times higher than those of their co-twin, who did not use cannabis before age 17 years....
In particular, early access to and use of cannabis may reduce perceived barriers against the use of other illegal drugs and provide access to these drugs.
The US Substance Abuse and Mental Health Services Administration (SAMHSA), stated in an Aug. 28, 2002 press release about SAMHSA's report; "Initiation of Marijuana Use: Trends, Patterns and Implications:"
"A new federal report released today concludes the younger children are when they first use marijuana, the more likely they are to use cocaine and heroin and become dependent on drugs as adults...
Increases in the likelihood of cocaine and heroin use and drug dependence are also apparent for those who initiate use of marijuana at any later age."
The US Drug Enforcement Agency (DEA) told ProCon.org in a Jan. 2, 2002 email:
"Among marijuana's most harmful consequences is its potential role in leading to the use of other illegal drugs like cocaine and heroin. Long-term studies of high school students and their patterns of drug use show that very few young people use other illegal drugs without first trying marijuana.
While not all people who use marijuana go on to use other drugs, using marijuana puts children and teens in contact with people who are users and sellers of other drugs, so there is more of a risk that a marijuana user will be exposed to and urged to try more dangerous drugs.
A recent study by Columbia University's Center on Addiction and Substance Abuse found a pronounced difference in future drug use between kids who used marijuana and those who did not. It revealed that teens who smoke marijuana are 85 times more likely to use cocaine than those who do not. This means the odds of using other drugs increases with the increased frequency of marijuana smoking."
The Eagle Forum stated in its brochure titled "Facts You Need to Know About ... Marijuana," from its website (accessed Mar. 2006):
"Since THC is continually in the body, the 'high' from pot gradually diminishes, and so pot smokers usually take other drugs to get a kick.
Nevertheless, they continue to smoke pot as they use the other drugs, because they think pot makes them 'feel good all the time.' Most pot smokers drink alcohol heavily, and many become so confused that they take cocaine and heroin....
Not all pot smokers use cocaine or heroin, but almost no one takes these drugs who has not used marijuana extensively.
Without pot smoking, there would be no demand for cocaine or heroin."
Joycelyn Elders, MD, former US Surgeon General, stated in a Dec. 14, 2002 editorial published in The Globe and Mail:
"Much of their [US drug-policy leaders] rhetoric about marijuana being a 'gateway drug' is simply wrong. After decades of looking, scientists still have no evidence that marijuana causes people to use harder drugs.
If there is any true 'gateway drug,' it's tobacco."
Andrew Morral, PhD, Director of the Safety and Justice Program in Infrastructure, Safety, and Environment at the RAND Corporation, stated in a Dec. 2, 2002 press release discussing his study with the RAND Corporation published in the British journal Addiction in 2002:
"We've shown that the marijuana gateway effect is not the best explanation for the link between marijuana use and the use of harder drugs.
An alternative, simpler and more compelling explanation accounts for the pattern of drug use you see in this country, without resort to any gateway effects. While the gateway theory has enjoyed popular acceptance, scientists have always had their doubts. Our study shows that these doubts are justified...
The people who are predisposed to use drugs and have the opportunity to use drugs are more likely than others to use both marijuana and harder drugs. Marijuana typically comes first because it is more available."
Lynn Zimmer, PhD, Professor Emeritus at Queens College at the City University of New York, stated in his 1997 book Marijuana Myths - Marijuana Facts:
"In the end, the gateway theory is not a theory at all. It is a description of the typical sequence in which multiple-drug users initiate the use of high-prevalence and low-prevalence drugs.
A similar statistical relationship exists between other kinds of common and uncommon related activities. For example, most people who ride a motorcycle (a fairly rare activity) have ridden a bicycle (a fairly common activity). Indeed, the prevalence of motorcycle riding among people who have never ridden a bicycle is probably extremely low. However, bicycle riding does not cause motorcycle riding, and increases in the former will not lead automatically to increases in the latter.
Nor will increases in marijuana use lead automatically to increases in the use of cocaine or heroin."