A genetic study of 14,000 people in Europe and the US has shown that variations in segments of two proteins that serve as gateways for nicotine entry into brain cells can predict the risk of addiction.
The study by US and Canadian scientists has shown that people with specific gene sequence coding for these proteins are more likely to be addicted to nicotine than people whose sequences are subtly different.
The two proteins called alpha-3 and alpha-5 form sites on brain cells which are activated during the process of addiction. The findings were published today in the journal Molecular Psychiatry.
â€œPharmaceutical companies can now study these targets and develop new drugs that could help people quit (smoking),â€ Wade Berrettini, professor of psychiatry at the University of Pennsylvania Medical School and lead investigator in the study, told The Telegraph.
Existing anti-nicotine medications are not always effective.
Previous studies from Australia, North America, Scandinavia and China had indicated that the tendency for habitual heavy smoking â€” up to 20 cigarettes a day â€” was influenced by the genetic makeup.
Researchers have estimated that two-thirds of the risk of heavy smoking is genetic â€” believed to be a combination of several genes, each of which contributes to a small amount of the risk.
In the new study, the American-Canadian team found that variations in alpha-3 and alpha-5 could be used to predict the number of cigarettes per day during the period of heaviest smoking.
Existing medications, including nicotine replacement patches, are effective only for a few months in heavy smokers. â€œWe could also use the genetic variations of alpha-3 and alpha-5 to determine whether they can predict the ability of people to quit using existing drugs,â€ Berrettini said.
The findings also raise the possibility â€” although there is no evidence for this yet â€” that people with certain variations in the alpha-3 and alpha-5 genes might find it easier to quit smoking than others.
â€œThis could be confirmed through analysis of genetic variations between people who have quit successfully and those who repeatedly return to nicotine after trying to quit,â€ Berrittini said.
Public health specialists believe that many people around the world, aware of the health risks of tobacco, are trying to quit but are unable to do so. Theyâ€™re in the league of the American writer Mark Twain who is said to have once quipped: â€œQuitting smoking is easy, Iâ€™ve done it a hundred times.â€
Sources:The Telegraph (Kolkata, India)