Genetic Makeup Affects Reaction to Drugs

The same drug can induce markedly different responses in different people depending on their genetic characteristics.

For example, in a study conducted by Dr. Nora Volkow of the Brookhaven National Laboratory, Ritalin, a stimulant which causes dopamine to spike, was given to two groups. The first group consisted of people who were born with a mutation to a gene that decreases the number of dopamine receptors in their brain’s Reward System. The second group didn’t have the mutation and had a more typical number of dopamine receptors.

“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,” Dr. Volkow 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 (For more click on The Dopamine DRD2 Gene)

Genetic makeup also affects tolerance to drugs. Research shows that people with a high tolerance to alcohol are more likely to become addicted to it. For example, researchers at the University of California in San Diego conducted an experiment involving 400 men in their 20s, all of whom had alcoholic fathers. They were given alcohol and tested for tolerance. Ten years later they were interviewed and 60% of the men with high tolerance had become alcoholics.2

Conversely, approximately 40% of Asians carry genes that hasten alcohol’s metabolism by as much as 200 times, overwhelming the body’s ability to cope with the toxic byproducts, and causing significant discomfort after consuming even small amounts of alcohol. This predisposition has also been discovered outside of Asia,3 and in about half of Jews.4 People with this genetic characteristic have a very low risk of alcoholism.

For the next article in the Genetic and Environmental Components of Addiction series click here.

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1. What’s the Lure of the Edge? The Answer Is All In Their Heads, New York Times, June 20, 2005.
2. A Serious Buzz; San Francisco Magazine, Oct. 2000.
3. A Form of the Alcohol Dehydrogenase Gene May Protect Afro-Trinidadians From Developing Alcoholism;, Jan. 30, 2007.
4. A Few Too Many, The New Yorker, May 26, 2008.
5. Genetics and Alcohol Consumption;, May 19, 2007.

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