Marijuana isn’t a gateway drug and doesn’t increase aggression

Mitch Earleywine Professor of Psychology, SUNY Albany
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In a recent Daily Caller article entitled “Why we shouldn’t legalize marijuana,” The Heritage Foundation’s Charles Stimson urges voters to avoid ending cannabis prohibition. However, Stimson has been badly misinformed and his arguments are based on a serious misreading of the scientific evidence. His first sentence suggests that cannabis is an addictive gateway drug. Real research, published in the peer-reviewed scientific journals mentioned below, says otherwise. In fact, numerous polls of scientists and extensive research on humans and animals reveal that the plant’s addictive potential is less than that of caffeine. (See Nutt et al., 2007 in the respected medical journal Lancet and Gore and Earleywine’s chapter in the Oxford University Press book Pot Politics). No study has ever suggested that 30% of those who try it become dependent.

The notion that cannabis is a gateway drug has been so roundly disputed that modern scientific journals rarely publish work on this issue anymore. Most people who try the plant not only do not go on to use hard drugs, they do not even go on to use the plant regularly. Many who use hard drugs do so before they try cannabis, and the vast majority of those who try cannabis have never even seen hard drugs. (See Blaze-Temple and Lo, 1992, in The British Journal of Addiction as one of many, many examples.) In fact, a study published in the August issue of The Journal of School Health asserts that it is actually alcohol use that is a predictor for progression to harder drugs.

The thought that marijuana increases aggression is also in error, as has been established for decades. Laboratory research shows that those who have recently ingested the plant are no more aggressive than those who ingested a placebo, even when they are provoked. (See Myerscough and Taylor, 1985, in The Journal of Personality and Social Psychology, and Taylor et al., 1976 in the journal Aggressive Behavior.) Once the legal drug alcohol is taken into account, there is no link between cannabis and hostility. (See Denson and Earleywine, 2008 in The Journal of Aggression, Maltreatment & Trauma.)

Stimson’s other misstatements and half-truths also lack empirical support, but I’m sure you get the idea. I have occasionally admired The Heritage Foundation’s support for free markets, individual liberties and smaller government. Surely these people do not want to jail citizens for owning a plant. An educated voter is the best kind. Let’s make sure no one is misinformed before casting a ballot on this, or any, issue.

Mitch Earleywine, Ph.D., is a professor of psychology at the State University of New York at Albany.

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Mitch Earleywine