What Neuroscientists Say About “Born Addicts”

Neuroscientists estimate that 50% of the risk of addiction is genetic, 50% environmental. But that’s for the population as a whole; it doesn’t provide much useful information on individual risk, which isn’t easily quantifiable. Individual risk depends not only on genetic makeup but the environment people grow up in as well — genes and the environment are constantly interacting; genetic expression can be turned “on” or “off” depending on environmental factors.

Genetics clearly plays an important role in how people react to drugs. Identical doses of the same drug are experienced quite differently by people with differing genetic makeups. Dr. Nora Volkow, one of addiction’s pre-eminent  researchers, gave two groups Ritalin, a stimulant that causes dopamine to spike, while undergoing brain scans. One group had a normal level of dopamine receptors in their reward centers while the other had fewer receptors, making their reward systems more sluggish. “And lo and behold, the people with low levels of dopamine receptors in their brains were the ones who liked the way Ritalin made them feel,” she said. “Those who had high concentrations of receptors in their brains said the Ritalin made them feel very unpleasant. They felt like they were losing control. One almost had a panic attack.”1

On the other hand, some genetic makeups carry much lower risk. A significant minority of Asians, for example, have a gene that increases the speed at which alcohol is metabolized. This quickly results in higher concentrations of toxic byproducts, overwhelming the body’s ability to neutralize them and causes discomfort even after ingestion of small amounts of alcohol. Unsurprisingly, these people are at very low risk for alcoholism (though they may have a more normal risk when it comes to other drugs of abuse). Accordingly, scientists say there’s a wide spectrum of risk for addiction, ranging from highly pre-disposed to it to highly pre-disposed against it.2 (For more click on Genetic and Environmental Components of Addiction.)

Further complicating the picture, it’s nearly impossible, given the current state of the art in neuroscientific research, to separate out the role genes play from the role environment plays. Genes don’t act alone, they act in response to the  environment each person encounters. So people with nearly the same genetic makeup but who grow up in different environments may have significantly different genetic expression.

Neuroscientists are notoriously cautious people. So, while they agree there’s a spectrum of risk, tied to the confluence of genetic and environmental factors, researchers aren’t ready to say some have such a high predisposition that they’re “born addicts.” That hasn’t yet been demonstrated by the controlled experiments neuroscientists rely on.

But they come pretty close. For example, some people have an in-born mutation to their dopamine D2 genes which decreases the number of dopamine receptors in their Reward System and renders it less efficient (like one of the groups in the Ritalin experiment cited above). Dr. Ernest P. Noble, a professor at UCLA, has studied people with this mutation. He says they experience life less intensely because their neurons are innately under-stimulated. They may self-medicate to compensate, he says.4 In a direct echo of the born-addict stories I heard at AA meetings, Dr. Noble says they describe their first drug-taking experience as filling a hole they’d always felt. They often reported the first time they felt normal was after their first drink or drug.5

So neuroscientists come close to agreeing there are born addicts even if they aren’t yet willing to make that final leap. But those who attend 12-Step meetings regularly and hear “born addict” stories over and over know it’s just a matter of time.

For more on this subject, click on Are “Born Addicts” Doomed?

Click here to return to the Questions About Addiction Menu.


1. Genetic Studies Promise a Path to Better Treatment of Addictions, New York Times, Nov. 14, 2000.

2. Genetics and Alcohol Consumption; medicalnewstoday.com May 19, 2007.


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