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

[unspun]

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.

---

^[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.

---

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.

---

RAND Home Page

[unspun]

My sentiments are with you, hop. Hope to respond, 'ere long.

[unspun]

This thread isn't about what percentage of users of marijuana become more frequent users or addicted users of marijuana.

[unspun]

(by the way, the drugs weere mostly used because of injuries).

This all means it's likely you don't fit the profile refered to in the article.

[unspun]

This thread isn't about what percentage of users of marijuana become more frequent users or addicted users of marijuana.

[MrLeRoy]

This thread isn't about what percentage of users of marijuana become more frequent users or addicted users of marijuana.

It's not about how addictive crack or heroin is, either; I trust you'll be complaining to Republic of Texas.

[headsonpikes]

blush ;^)

[rb22982]

This thread is about marijuana and why it should or shouldn't be illegal, therefore it is relevent. Moreover, I was responding to someone anyway so you shouldn't direct that comment at me in the first place.

[rb22982]

very nice post

[monkey]

I.e., either way you slice it, if intoxicants including marijuana are more freely available, they will simply add to the use of hard drugs, among those who are so inclined.

That's not what the study says. How did you reach that conclusion?

[Hebrews 11:6]

The Meek SHALL NOT Inherit the Earth, IMHO

Then your beef, friend, is with Jesus, not with me.

[Hebrews 11:6]

so I must ask you, what is the point of your paranoia?

I'm not paranoid, friend. My point is simply that using these drugs is illegal. Therefore, anyone using them is committing a crime. Got it?

[tpaine]

IMO, communities of people have always expected their members to adhere to certain behaviors, and to avoid others. Adherence to these various communal mores are not objectionable to me, at all. If the good folks of Hooterville despise the consumption of red meat, for instance, then Hooterville can decline to issue business licenses to butchers; if I think that's stupid, I can leave town.
-HoP-

Exactly, the Hooterville majority can 'regulate' the offensive [to them] practice of butchering/ selling/consuming red meat in public. -- But they cannot prohibit or criminalize this foul practice in the privacy of the home.
- This would violate our inalienable right to eat what we wish.

Thanks for a great essay. I think you should come up with a controversial title, and post it to a thread of its own.

[Hebrews 11:6]

If you think that exceeding posted speed limits suggests a tendency toward criminal activity...
Exceeding posted speed limits is criminal activity.

Not all laws are inherently good.
I agree completely. I come at this, if you're interested, from a Biblical perspective. Romans 13 commands Christians to obey the civil authorities, who derive their authority from God. Therefore, the default position is to obey. Other Scriptures add that where there is a conflict between their civil law and God's law, then that is an inherently un-good law, and we must instead obey God's law.

[tacticalogic]

Unfortunately, this doesn't address what should be done when civil law is in conflict with itself.

[Hebrews 11:6]

DFW, I take it, is Dallas-Fort Worth? I drive 120 miles daily in L.A., so I know something about staying alive on the freeway--and I do drive the speed limit. Try it, you'll like it! By the way, I don't believe for a moment that driving the speed limit breaks a law against impeding traffic.

With respect to your challenge about living in a country where owning a Bible is illegal--you've oversimplified it. Christians are commanded by that Bible (Romans 13) to obey the civil laws, because the civil authorities derive their authority from God. But that same Bible also makes clear that where the civil law contradicts God's law, we are to obey God's law instead. Doing so may subject us to paying the penalty in that society for breaking its laws, as millions of Christians have knowingly chosen to do.

[MrLeRoy]

where the civil law contradicts God's law, we are to obey God's law instead. Doing so may subject us to paying the penalty in that society for breaking its laws

But will it incline us to break other laws?

[MrLeRoy]

Romans 13 commands Christians to obey the civil authorities, who derive their authority from God. Therefore, the default position is to obey. Other Scriptures add that where there is a conflict between their civil law and God's law, then that is an inherently un-good law, and we must instead obey God's law.

That's one way of reconciling Romans 13 with those other passages; another is to conclude that a Christian must discern whether the government is acting as "God's servant" in any particular case and obey only if it is.

[Hebrews 11:6]

...a Christian must discern whether the government is acting as "God's servant" in any particular case and obey only if it is.

That might be a reasonable conclusion but for these objections:
1. It would be too complicated and wearisome to decide every time; there are enough occasions where we must decide without going through that arduous process in each instance. I am saying that, practically, no one could actually live that way and still function normally.
2. The mandate in Romans 13 is pretty strong. It says "Obey," not "think about it first." In other words, taking Scripture as a whole--as we're obliged to do--the sense I get is that we're to Romans 13 but watch out for exceptions, rather than Romans 13 and watch out for exceptions.

[Hebrews 11:6]

Unfortunately, this doesn't address what should be done when civil law is in conflict with itself.

And your point is?

[MrLeRoy]

1. It would be too complicated and wearisome to decide every time; there are enough occasions where we must decide without going through that arduous process in each instance. I am saying that, practically, no one could actually live that way and still function normally.

Why would the process be arduous every time?

2. The mandate in Romans 13 is pretty strong. It says "Obey," not "think about it first." In other words, taking Scripture as a whole--as we're obliged to do--the sense I get is that we're to Romans 13 but watch out for exceptions, rather than Romans 13 and watch out for exceptions.

Almost everything in the Bible is pretty strong.

An interesting question was raised in another thread: in light of your interpretation of Romans 13, was our revolting against Great Britain a Christian act?