Why are some people who start smoking in their early teens hooked on cigarettes for life, while others find it relatively easy to give up? Scientists at the University of Utah show that genetic differences are part of the answer.

    Their research, published on the 11 July in the journal PLoS Genetics, focuses on variations in a gene that determine the structure of the “nicotine receptor” – the protein in the brain that interacts with nicotine, the most addictive chemical in cigarette smoke.

    The researchers studied DNA samples from 2,827 long-term smokers. They assessed the level of nicotine dependence and recorded the age at which people began smoking, the number of years they smoked and the average number of cigarettes smoked a day.

    One variant of the gene put smokers at greater risk of heavy nicotine dependence as adults but only if they started smoking regularly before the age of 17. A second variant reduced the risk of later addiction.

    The authors conclude: “Identification of genetically high-risk individuals who would benefit from proactive interventions, such as adolescent education and cessation clinics, may result in a population with a lower rate of adult nicotine addiction.”

    為何有些從十幾歲開始吸煙的人，一輩子都擺脫不了香煙，而其他人戒嚴卻相對容易呢？美國猶他大學(University of Utah)的科學家表示，基因差異是造成這種現象的原因之一。

    他們的研究結果7月11日發表在公共科學圖書館（Public Library of Science，簡稱PLoS）遺傳學期刊上，著重于研究決定“尼古丁受體(nicotine receptor)”結構基因的變體。尼古丁受體是大腦中的一種蛋白質，它可與香煙煙霧中最令人上癮的化學成分尼古丁互相作用。

    研究人員調查了2827名長期吸煙者的DNA樣本。他們對每名吸煙者的尼古丁依賴水平做出評估，并記錄下他們開始吸煙時的年齡、有多少年吸煙史以及平均每天吸多少支煙。

    如果17歲前就開始有規律地吸煙，該基因的一種變體可加大該吸煙者在成年后對尼古丁產生嚴重依賴的風險。而該基因的另一種變體則可以降低成年后對尼古丁上癮的風險。

    研究報告的作者總結道：“找出那些在基因上容易上癮的人，有助于對他們進行積極干預，如進行青春期教育和戒煙治療，這將降低成年人中對尼古丁上癮的人口比例。”