I Smell a Rat

I Smell a Rat

I Smell a Rat

The conventional wisdom debunked.
Aug. 10 1997 3:30 AM

I Smell a Rat

Should we take seriously the new scientific "findings" that pot is as addictive as heroin?

The National Institute on Drug Abuse concludes every press release on its Web site with the boast that NIDA supports more than 85 percent of the world's research on the health aspects of drug abuse and addiction, and publicizes the results of that research.

Advertisement

That the government's drug warriors are the customers for most health studies on drug abuse--and that they aggressively peddle these studies--doesn't make the studies automatically suspect. In fact, the science behind NIDA-funded studies is reputable 99.99 percent of the time. But what is suspect is the spin NIDA routinely applies to its sponsored studies, such as the successful flackery that accompanied the marijuana study that appeared in the June 27 edition of Science.

The authors of the Science paper--"Activation of Corticotropin-Releasing Factor in the Limbic System During Cannabinoid Withdrawal"--suggest in their conclusion that marijuana may be as addictive as heroin and cocaine, and that pot's "subtle disruption" of brain chemistry may leave users " 'primed' for further disruption by other drugs of abuse."

Both the New York Times and the Washington Post published pieces based on the NIDA-sponsored study. The first sentence of the Times story is indistinguishable from that of the NIDA press release.

The Times: "People who regularly smoke large amounts of marijuana may experience changes in their brain chemistry that are identical to changes seen in the brains of people who abuse heroin, cocaine, amphetamines, nicotine and alcohol, scientists have found."

Advertisement

NIDA: "Long-term use of marijuana produces changes in the brain that are similar to those seen after long term use of other major drugs of abuse such as cocaine, heroin, and alcohol."

Although the Post's lead was more original, it, too, followed the NIDA line. "Marijuana may be a far more insidious drug than generally thought," the Post reported, "and apparently alters the brain chemistry of pot smokers in ways that may make them particularly vulnerable to 'hard' drugs such as heroin or cocaine, two independent research groups have found."

Illustration by Robert Neubecker

How seriously should we take these findings? In one study, researchers injected rats with cannabinoids--chemicals that act like THC, the main active ingredient in marijuana--for weeks, habituating them to the compounds. Because cannabinoids can linger in the system for some time, few marijuana users experience anything approximating physical withdrawal if they stop smoking. To mimic cold-turkey withdrawal, the researchers then injected these habituated rats with a drug that "blocks" the effects of all cannabinoids. Following the injection of the blocker, the researchers observed an increase of the brain chemical CRF in the amygdala, a portion of the brain involved with the emotions of fear and aggression. The presence of CRF in the amygdala is associated with stress and anxiety. Withdrawal from heroin, cocaine, and alcohol also increases CRF in the amygdala. The authors of the paper lean on these findings to suggest that marijuana acts on the brain as other drugs of abuse do, and that users who stop smoking marijuana might indulge in heroin, cocaine, or alcohol to stave off the unpleasantness of increased CRF in the amygdala.

A second marijuana study (not financed by NIDA) that also appeared in the June 27 Science, and which was also mentioned in the Times and Post articles, further investigates the effects of cannabinoids on rats. The study found an increase of the neurotransmitter dopamine in rats' nucleus accumbens--often termed "the pleasure center of the brain"--following several cannabinoid injections. Most recreational drugs, like heroin, cocaine, alcohol, and nicotine, increase dopamine in the accumbens. While recognizing that other researchers have tried and failed to induce an increase of dopamine in the accumbens by injecting cannabinoids, the authors use their results to suggest that marijuana is more like heroin and cocaine than was previously thought.

Advertisement

Before going any further, consider two points. First, injected cannabinoids may not mirror the effects of smoked marijuana. There are several other chemicals in marijuana that may modify the effects of THC alone, and smoking a drug is a different experience from injecting it. (Imagine the difference between smoking a cigarette and injecting pure nicotine directly into a vein.)

Second, rats are not humans. This does not mean cannabinoid research on rodents is worthless. But there are several pharmacological and social differences that reduce the relevance of rat research to social policy. And since the pleasure derived from smoking marijuana is a core issue, consider a third point: Rats don't like pot.

I know this firsthand from my own research on cannabinoids and rats. Initially, I felt guilty about drugging rats and then killing them for the necessary dissection. "At least they're getting stoned first," I rationalized. Then I realized that being stoned means very different things to rats and humans. Marijuana makes rats slothful, and they excrete all over themselves. Before the injection they're quite friendly--these are lab animals, remember, not hardened street rats. After the injection they--honestly--seem rather depressed.

Another fun fact about rats and pot is that rats won't self-administer any cannabinoid. When given the choice of receiving an injection of THC or a placebo, rats consistently choose the placebo. And when given the choice between a placebo and the cannabinoid blocker, rats choose the blocker. Tens of millions of humans, as we know, willingly partake of marijuana, and these differences between rat and human behavior should discourage us from using two rat studies to assert that a) marijuana is addictive in the same way as harder drugs are and b) marijuana primes humans for addiction to harder drugs.

The Science studies also ignore simple truths about brain chemistry. Consider that sex causes dramatic increases in dopamine. Laughter, too, increases dopamine. The syllogism that dopamine equals pleasure and pleasure leads to addiction just doesn't apply directly to human behavior. How seriously would anyone take a researcher who suggested that laughter could lead to drugs and deadly addictions?

And the CRF-producing process associated by the researchers with marijuana withdrawal is not unique to drugs. Just as sex increases dopamine in the accumbens, stubbing one's toe may ignite neurological anxiety. Indeed, chronic toe-stubbing can lead to the abuse of analgesics like aspirin. Again, the science reported in Science is reputable. It's just taken out of context.

Also lost in the mix is that fact that other published NIDA-funded and non-NIDA-funded studies have found that cannabinoids don't increase dopamine in the accumbens. Still other researchers have shown that monkeys don't like the effects of cannabinoids any more than rats do. But findings like these that don't support the government's drug agenda are rarely catapulted into the news by the publicity machine.

So let's set aside for a moment the drug preferences and predilections and propensities of rats and turn our attention back to humans. Of the estimated 70 million Americans who have tried marijuana, only 1 percent have gone on to heavy cocaine use. Perhaps NIDA and the pliant journalists should inject themselves with a big dose of common sense.