The Vietnam Natural Experiment

“In 1971, Nixon's White House commissioned a study on heroin use in Vietnam. What Lee Robins found challenged every assumption the drug war was built on.”

In 1971, reports reached Congress that approximately 20 percent of US soldiers in Vietnam were addicted to heroin, easily available, cheap, and more potent than what was available at home. The government commissioned Lee Robins, a psychiatric epidemiologist at Washington University, to study the situation.

What Robins found upended the standard model of addiction. She tracked soldiers after their return to the United States and found that most of those who had been addicted in Vietnam did not become addicted again after they came home: about 5 percent relapsed to addiction within the first year and about 12 percent within three years, most without treatment or formal support. Many used heroin at least occasionally after returning, but few became addicted again.

This was not supposed to be possible. The standard model of heroin addiction, which informed drug policy, held that the drug created a pharmacological dependency that the body could not simply discontinue, that withdrawal was a physical process requiring medical management and that relapse was the default outcome of exposure. Robins's data showed something different: that the vast majority of people who had become dependent on heroin in one environmental context did not continue that dependence when the environmental context changed radically.

Johann Hari uses the Vietnam study as one of his strongest empirical arguments for the connection model. Most of the soldiers did not need treatment to avoid addiction after returning; Hari's reading is that their home environments offered alternatives. The drug was the same. The context was different.

The study's implications are significant and contested. Critics note that heroin in Vietnam was different in purity and administration route from street heroin in the US, and that the cultural context of returning home itself is a complex variable. Robins acknowledged these complications in her later work. The study remains the most dramatic natural experiment available on the relationship between environment and addiction, and its conclusion, that context shapes pharmacological dependence more powerfully than the model predicted, is supported by the data regardless of how the mechanism is interpreted.

Sources

• Hari, Chasing the Scream (2015)
• Robins et al., Vietnam Veterans Three Years After Vietnam, Am J Addict (2010 reprint); Robins, Addiction (1993)
• Wikipedia, Lee Robins
• Robins, Helzer & Davis, Archives of General Psychiatry (1975)