Scientists find key to stubbing out nicotine addiction

Scientists have identified the brain cells responsible for nicotine addiction. The research could pave the way for people to stub out their need for cigarettes once and for all.

During a study of two interconnected regions of the brain known to play a role in addiction – the medial habenula and the interpeduncular nucleus (IPN) – scientists found that changes to a particular set of neurons in nicotine-addicted mice could reduce the rodents’ dependency on the drug.

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When exposed to nicotine, the medial habenula is supposed to send a signal to the IPN telling it to limit its effects by preventing maximum intake. In its research, the team from New York’s Rockefeller University, Mount Sinai Medical School and the National Institute of Biological Sciences in China, found that prolonged exposure causes changes in a group of neurons known as Amigo1, a change that disrupts the communication between the habenula and the IPN. This means the message to “stop smoking” is never delivered, causing higher levels of addictiveness.

The study, published in the journal PNAS, showed how mice who had been served nicotine-water in a chamber for six weeks displayed their addictive behaviour by choosing to remain in a chamber when given the choice of leaving to spend time in another. When the team later conducted the same experiment on mice genetically modified to remove the Amigo1 neurons, they found that the mice did not display a preference for the drug by choosing to stay in another chamber rather than the one they were served nicotine.

"If you are exposed to nicotine over a long period you produce more of the signal-disrupting chemicals and this desensitizes you," scientist Ines Ibanez-Tallon of Rockefeller University told Medical Express. "That's why smokers keep smoking."

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Cigarette smoking is responsible for more than 480,000 deaths per year in the US, according to the CDC, with the total economic cost of smoking thought to be around $300 billion per year. Worldwide, tobacco consumption causes nearly six million deaths per year. If current trends continue, that figure will rise to eight million by 2030.

Earlier this month research from Bristol University in the UK found that after 500 participants were asked to select a smoker and non-smoker from 23 sets of twins, both men and women were able to identify the smoker. While the research found that non-smoking elements were found to be more attractive to the opposite sex, it noted a similar trend from same sex people.