Those who advocate the “gateway drug” theory believe that young people start abusing drugs by using the mildest ones and the ones that are legal first, and then they progress to more dangerous, addictive and illegal substances. The majority of scientific studies back up the idea of progressive drug use. The typical sequence for most addicts is alcohol, tobacco, marijuana, hallucinogens, pills, heroin and finally cocaine, according to research from the University of Washington School of Medicine. Gateway drugs are therefore most commonly known as cigarettes, alcohol and marijuana, but some experts also add “inhalants.” Inhalants are household chemicals such as gasoline and glue that people sniff in order to “get high.” Advocates of the gateway drug theory believe that people progress to hard drugs for reasons based in pharmacology and sociology.
The “pharmacological” basis for the gateway drug theory is that marijuana and other gateway drugs “prime” the brain for addiction. Many studies indicate that the human brain keeps developing until age 25 years old, and that it is easier to become addicted to drugs and alcohol when the brain is still immature. In studies of laboratory rats, those who are injected with the psychoactive chemical in marijuana in their adolescence are more likely to choose and use heroin if it becomes available in their adulthood, when they are compared to rats in a control group that were not exposed to marijuana. Marijuana may somehow interfere with certain brain receptor cells and therefore damage its natural ability to feel pleasure, which in turn leads to chemical dependencies. Using these ideas backed up by certain research, some experts believe that the best way to control drug addiction in society is to deter young people from using gateway drugs like marijuana.
In sociological terms, the theory is if young people begin using marijuana in high school, they gain access to street dealers who will sell them “harder” drugs. The dealers of course have an incentive to do this, because by creating more addicts, they are creating a steady demand for their products. This theory based in sociology also holds that young people are less likely to use gateway drugs if they are in an environment that is not drug-friendly, so the government should have policies that keep drugs as scarce and illegal as possible.
The gateway drug theory can be refuted by certain other studies, particularly the ones that point to genetic factors and personality traits that make some individuals more susceptible to drug abuse. Studies of identical twins raised separately indicate that some people are genetically more likely to become drug addicts even if they are raised in families and environments where drug abuse is uncommon. Identical twins have similar rates of alcoholism, for example, even when raised by adoptive parents who do not drink. Genetic vulnerability may account for a factor of 50% of the risk for drug or alcohol abuse. It is not known which gene or combination of genes make a person more susceptible to chemical dependencies.
It is also known that certain personality traits lead not only to early experiments with drugs but also to other forms of risk taking, such as delinquency and dropping out of school. It may be that these personality traits are inherited and this in turn leads to drug abuse. Under this theory, a certain percentage of the population has such personality traits and/or a genetic vulnerability to drug abuse, and this group will experiment with drugs when they are young regardless of which “gateway drugs” are available to them.
The other side argues that all drugs should be illegal for young people at least until their brains are physically mature. Right now the United States is in the middle of a debate about the legalization of marijuana. Those in favor point out that this drug is no more dangerous than others that are already legal, and that it has legitimate medical uses. They say that the gateway drug theory has been disproven and that those who experiment with drugs at an early age would use hard drugs as adults regardless of what substances are available to them in high school. They point to policies in effect in the Netherlands, where marijuana is legal and young people abuse it at about the same rates as American children.