A Comeback for the Gateway Drug Theory?

 In Medical Marijuana

The New York Times / 

If you grew up as part of the D.A.R.E. generation — kids of the 1980s and ’90s who learned about drugs from alarmist public service announcements — you know all too well the dangers of so-called gateway drugs. Go to bed with marijuana or beer, you were taught, and risk waking up with cocaine or heroin.

Three decades later, scientists and politicians still debate whether using “soft” drugs necessarily leads a person down a slippery slope to the harder stuff. Critics note that marijuana has, in some cases, been shown to actually prevent people from abusing other substances. And even D.A.R.E. now acknowledges that the overwhelming majority of people who smoke pot or drink never graduate to pills and powders.

But new research is breathing fresh life into the perennially controversial theory, and the timing seems apt. As marijuana legalization and the opioid epidemic sweep across the country, parents are once again questioning the root causes of addiction. And politicians opposed to legalization, including Attorney General Jeff Sessions and Gov. Chris Christie of New Jersey, have routinely used the gateway effect as their chief argument against reform.

Is the science on their side?

A Columbia University study published in November in Science Advances showed that rats exposed to alcohol were far more likely than other rats to push a lever that released cocaine. The researchers also found that the alcohol suppressed two genes that normally act as cutoff switches for the effects of cocaine, creating a “permissive environment” for the drug within the rodents’ brains.

Most critical to the viability of gateway theory, both studies found there was no enabling effect when the order of the drugs was reversed. Taking cocaine did not make the rodents more susceptible to the effects of alcohol or nicotine, supporting the idea that some drugs are better positioned than others to act as place-setters.

“Now that we’ve done the animal experiment, we see that using one drug changes your brain in such a way that using another drug becomes more rewarding,” said Dr. Kandel, a professor of sociology at Columbia University. “And there is an order. Cocaine doesn’t create this effect.”

Critics are quick to point out the shortcomings in these studies, including the assumption that rodents and humans respond similarly to narcotics. “I think it sounds like a relatively lame attempt to resuscitate a theory that’s been largely debunked,” said Ethan Nadelmann, the founder and former executive director of the Drug Policy Alliance. “The simple fact that they’re involving studies on rats” to make claims about people is “a real stretch,” he said.

Dr. Nadelmann also noted that many previous studies showing how one drug enhances the effect of another have contradicted the gateway theory. A 2008 paper found that by taking marijuana, chronic-pain sufferers could reduce their doses of pain-relieving opioids, for example. And people who combine marijuana with prescription opioids are not more likely to abuse alcohol or other drugs, research has shown.

Another knock on the gateway theory: In Japan, where marijuana use is far lower than in most Western countries, 83 percent of illicit drug users did not start out smoking pot, according to a 2010 study. And there is now mounting evidence that factors such as poverty and poor social environment are a greater predictor of hard drug use than early exposure to soft drugs.

In 1999, reporting on the dangers of medical marijuana for Congress, the Institute of Medicine of the National Academy of Sciences declared “there is no conclusive evidence that the drug effects of marijuana are causally linked to the subsequent abuse of other illicit drugs.” The report did not address nicotine or alcohol.

What the medical community knows about addiction has evolved significantly since the 1930s, when a team of researchers introduced an early version of the gateway concept. Known as Stepping Stone Theory, it was based on the researchers’ observation that 100 percent of the heroin addicts they interviewed had first used marijuana. Their conclusion: Marijuana leads inexorably to heroin use.

Read the full article on nytimes.com