Nicotine is less addictive for smokers who have a particular genetic variant

Researchers have found that a particular gene called OPRM1 contains instructions for building a type of receptor that allows opioids – including drugs like heroin and morphine as well as opioids produced inside the body – to make their presence known in the brain, triggering release of the feel-good chemical dopamine. Nicotine prompts the body to produce more of its own opioids, which in turn releases more dopamine. At a particular location on the OPRM1 gene, many people inherit an A (short for adenine) from both parents. But some people inherit a G (short for guanine) from at least one parent. That small difference can affect whether smokers become addicted to nicotine – and the cigarettes that contain them. Researchers have found that having a G version of the gene made nicotine less appealing and easier to give up compared with having the double A version of the gene.