According to the National Institute on Drug Abuse, someone who smokes pot is 104 times more likely to use cocaine than a person who never had marijuana.
But does correlation equal causation? In this case, it seems the answer is no. Not only is there a lack of conclusive evidence to support the gateway drug theory, but there are other factors that explain why people may use marijuana first.
What Is the Marijuana Gateway Theory?
When someone calls marijuana a gateway drug, what they’re actually saying is that smoking marijuana causes a person to abuse other drugs.
We can prove or disprove the gateway theory in two ways:
- Biological: Does using marijuana cause biological changes that predispose a person to abuse other drugs?
- Social or Cultural: Are gateway patterns similar throughout all social and cultural situations?
Breaking Down the Biological Research
There is some research that seems to support biological ways in which marijuana could be a gateway drug, but the research was mostly done on rats and has been largely inconclusive.
For example, a 2007 neuropsychopharmacology study found that when adolescent rats received THC, they were more likely to "self-administer" heroin as adults. The THC rats were also more likely to increase their heroin usage over time. These findings aren't unique to marijuana, though. Nicotine and alcohol have been shown to have similar effects. Also, no such study has been done on humans.
Exploring Social and Cultural Reasons
When we talk about marijuana, it's difficult to ignore the issue of legality. Because marijuana is still illegal in many places, people who want to smoke pot must go through independent drug dealers. It's a fact that it's much easier to score pot on the street than heroin.
Could strict anti-pot laws entice people to make connections with drug dealers? Since drug dealers often deal in more than one type of drug, someone who smokes pot may find it easier to buy cocaine or heroin.
We can put this theory to the test by looking at Holland, where they have very liberal marijuana laws. If you've ever been to an Amsterdam café, you know how easy it is to get pot there. If pot is truly a gateway drug, we should expect most of Holland's pot smokers to move on to harder drugs. But this isn't the case.
One study looked at drug use around the globe to determine whether there were any patterns for gateway drugs. It found, somewhat conclusively, that people who used marijuana, alcohol, or tobacco were more likely to use drugs later. Interestingly enough, the connection was stronger in some countries than others.
Different countries had different patterns. For example, the study found that people in Japan weren't likely to use marijuana (only 1.6 percent used by age 29), but they were more likely to jump to using harder drugs than anywhere else. This may indicate that taking away marijuana would have no impact on heroin and cocaine use.
How Powerful Are Gateway Effects?
The federal government funds two large drug use surveys every year. And every year, they find that many more people use marijuana than cocaine or heroin. In 2009, for example, 2.3 million people admitted to trying pot while 617,000 tried cocaine and 180,000 did heroin.
If pot is truly a powerful gateway drug, why aren't more people led to cocaine and heroin each year? If marijuana were truly a gateway drug, it's reasonable to believe that we'd have an even larger opioid epidemic than we do.
Marijuana isn't the only drug accused of being a gateway drug. Many people believe that is the gateway drug for college students, and prescription painkillers are the gateway drug of choice for middle-aged women.
The question of whether marijuana is a gateway drug is one we've been asking each other for ages. It has even been definitively answered in 1999 by an official report from the Institute of Medicine:
"In the sense that marijuana use typically precedes rather than follows initiation into the use of other illicit drugs, it is indeed a gateway drug. However, it does not appear to be a gateway drug to the extent that it is the cause or even that it is the most significant predictor of serious drug abuse; that is, care must be taken not to attribute cause to association."
Although there is a definite correlation between marijuana and heavier drug use, you'll find the same correlation between alcohol or tobacco and heavier drug use.
Addiction is a multi-faceted disease. There are societal, demographic, and genetic factors of addiction to consider. So, someone who is predisposed to using drugs may be drawn to substances like weed, alcohol, or tobacco because they are much easier to get your hands on. From here, they may go on to try cocaine or heroin. This does not mean that alcohol, tobacco, or pot drove them to try heavier drugs.
For more information on marijuana and its relation to harder drugs, check out the following articles: