Using Marijuana May Not Raise the Risk of Using Harder Drugs (but look at alternative explanation)

RAND's Drug Policy Research Center ^ | December 2, 2002 | RAND's Drug Policy Research Center

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Using Marijuana May Not Raise the Risk of Using Harder Drugs

Marijuana is widely regarded as a "gateway" drug, that is, one whose use results in an increased likelihood of using more serious drugs such as cocaine and heroin. This gateway effect is one of the principal reasons cited in defense of laws prohibiting the use or possession of marijuana. A recent analysis by RAND's Drug Policy Research Center (DPRC) suggests that data typically used to support a marijuana gateway effect can be explained as well by a different theory. The new research, by Andrew Morral, associate director of RAND Public Safety and Justice, Daniel McCaffrey, and Susan Paddock, has implications for U.S. marijuana policy. However, decisions about relaxing U.S. marijuana laws must necessarily take into account many other factors in addition to whether or not marijuana is a gateway drug.

Support for the Gateway Effect

Although marijuana has never been shown to have a gateway effect, three drug initiation facts support the notion that marijuana use raises the risk of hard-drug use:

• Marijuana users are many times more likely than nonusers to progress to hard-drug use.

• Almost all who have used both marijuana and hard drugs used marijuana first.

• The greater the frequency of marijuana use, the greater the likelihood of using hard drugs later.

This evidence would appear to make a strong case for a gateway effect. However, another explanation has been suggested: Those who use drugs may have an underlying propensity to do so that is not specific to any one drug. There is some support for such a "common-factor" model in studies of genetic, familial, and environmental factors influencing drug use. The presence of a common propensity could explain why people who use one drug are so much more likely to use another than are people who do not use the first drug. It has also been suggested that marijuana use precedes hard-drug use simply because opportunities to use marijuana come earlier in life than opportunities to use hard drugs. The DPRC analysis offers the first quantitative evidence that these observations can, without resort to a gateway effect, explain the strong observed associations between marijuana and hard-drug initiation.

New Support for Other Explanations

The DPRC research team examined the drug use patterns reported by more than 58,000 U.S. residents between the ages of 12 and 25 who participated in the National Household Surveys on Drug Abuse (NHSDA) conducted between 1982 and 1994.^[1] Using a statistical model, the researchers tested whether the observed patterns of drug use initiation might be expected if drug initiation risks were determined exclusively by

• when youths had a first opportunity to use each drug

• individuals' drug use propensity, which was assumed to be normally distributed^[2] in the population

• chance (or random) factors.

To put it another way, the researchers addressed the question: Could the drug initiation facts listed in the first section of this brief be explained without recourse to a marijuana gateway effect?

Figure 1—Probabilities of Initiating Hard Drugs, Marijuana Users and Nonusers

The research team found that these associations could be explained without any gateway effects:

• The statistical model could explain the increased risk of hard-drug initiation experienced by marijuana users. Indeed, the model predicted that marijuana users would be at even greater risk of drug use progression than the actual NHSDA data show (see Figure 1).

• The model predicted that only a fraction of hard-drug users would not have tried marijuana first. Whereas in the NHSDA data 1.6 percent of adolescents tried hard drugs before marijuana, the model predicted an even stronger sequencing of initiation, with just 1.1 percent trying hard drugs first.

• The modeled relationship between marijuana use frequency and hard-drug initiation could closely match the actual relationship (see Figure 2).

The new DPRC research thus demonstrates that the phenomena supporting claims that marijuana is a gateway drug also support the alternative explanation: that it is not marijuana use but individuals' opportunities and unique propensities to use drugs that determine their risk of initiating hard drugs. The research does not disprove the gateway theory; it merely shows that another explanation is plausible.

Figure 2—Probabilities of Hard-Drug Initiation, Given Marijuana Use Frequency in the Preceding Year

Some might argue that as long as the gateway theory remains a possible explanation, policymakers should play it safe and retain current strictures against marijuana use and possession. That attitude might be a sound one if current marijuana policies were free of costs and harms. But prohibition policies are not cost-free, and their harms are significant: The more than 700,000 marijuana arrests per year in the United States burden individuals, families, neighborhoods, and society as a whole.

Marijuana policies should weigh these harms of prohibition against the harms of increased marijuana availability and use, harms that could include adverse effects on the health, development, education, and cognitive functioning of marijuana users. However, the harms of marijuana use can no longer be viewed as necessarily including an expansion of hard-drug use and its associated harms. This shift in perspective ought to change the overall balance between the harms and benefits of different marijuana policies. Whether it is sufficient to change it decisively is something that the new DPRC research cannot aid in resolving.

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^[1]In subsequent years, respondents have not been asked about their first opportunity to use various drugs.

^[2]That is, some people have a high or low propensity, but most people have a propensity near the middle of the range.

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RB-6010 (2002)

RAND research briefs summarize research that has been more fully documented elsewhere. This research brief describes work done in RAND's Drug Policy Research Center, a joint endeavor of RAND Public Safety and Justice and RAND Health. The research is documented in "Reassessing the Marijuana Gateway Effect" by Andrew R. Morral, Daniel F. McCaffrey, and Susan M. Paddock, Addiction 97:1493-1504, 2002.

Abstracts of RAND documents may be viewed at www.rand.org. Publications are distributed to the trade by NBN. RAND^® is a registered trademark. RAND is a nonprofit institution that helps improve policy and decisionmaking through research and analysis; its publications do not necessarily reflect the opinions or policies of its research sponsors.

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Or to read your question another way, we are morally committed to be hungry for wisdom and knowledge, and discern in humility rather than pride. (Rich man' "objectivism.")

One doesn't need to worry about acheiving an altered state of total objectivity, before acting. That is like religious mysticism. Instead we are to be subject to the truth, as we may ascertain it. (All truth is God's truth.)

[tacticalogic]

Instead we are to be subject to the truth, as we may ascertain it. (All truth is God's truth.)

As long as we don't arrive at the "truth" before we take the journey, or arrive there by a process of willful ignorance of anything that might lead in a direction we didn't intend to go.

[Mike4Freedom]

You are saying you prefer the concept of 4,500 amendments to the constitution,

Of course I don't want 4,500 amendments. What I want is a government that understands that there are things they may not do.

The whole idea of our founders, an idea that I thought was the basis of conservative thought, is that the people set up a government for certain limited purposes and wanted to make sure that the government, with access to force to achieve its ends, never exceeded those limits. This is necessary to prevent tyranny.

Even our elected officials must be limited by this highest law, which is very hard to amend-on purpose, or we will have a tyranny of the majority.

Otherwise, we might have some temporary majority of people who make less than some arbitrary definition of "rich" deciding to take all or most of the money of that minority who make over that number, the "evil rich". The constitution was supposed to protect the minority from that.

Or maybe the white majority decides to put the black or Arab minority in camps (for their protection, of course) or all sorts of horrible things that you could imagine.

There are plenty of unconstitutional things going on right now, including the War on Drugs, all manner of social programs, civil forfeiture without due process, no-knock searches, gun control, etc that would not happen if the constitution was obeyed. I would not be happy if each of these was an amendment, but at least they would have had to sell each individually through all the obstacles provided for amendment and this would have slowed down our decent into tryanny, if not stopped it altogether.

[Mike4Freedom]

Most that are for illegal drug use are void of morals or ethics as conservatives know them here at FR. The way that is addressed by these pro-addiction folks is that they try to redefine morals and ethics DOWN by giving both of those words little value in their limited vocabulary.

Actually the libertarian view is intensely moral. We have a first principle that we summarize as "no initiation of force" that is our moral guidepost. This is just a grown up version of the lesson you were taught on the playground by your parents when you were about 3 years old. If two kids got into a fight, the adults broke it up and wanted to know who started it. The starter was punished and the defender was comforted.

Using that principle, we see a drug user as a person not initiating force but minding his own business. We see the government that wants to punish him for that as the initiator of force and the criminal. On the other hand, if a person assaults another, then the government arrests him, it is applying either defensive or retaliatory force and is doing right. This is where we come up with the phrase "victimless crime". If no one was hurt or stolen from, against whom was force initiated?

So I am not impressed by your moral statements because I do not see their basis as moral at all. A drug user is morally correct. A drug warrior is a vicious criminal. For this purpose drug warrior includes every step in the process of punishing drug users: The congressmen, the judges, the prosecutors, the police, the prison guards, and the politically active people who support this evil.

A drug user who commits other, real crimes to facilitate his drug use is guilty but the drug warriors who created the situation and made the drugs so expensive are accomplices to those crimes and equally guilty.