中老年人戒烟的健康作用在我国尚缺乏前瞻性证据且谬误流传，而国人主动戒烟成功率明显低于西方的原因与其是否存在特有的成瘾遗传背景尚不清楚。本研究拟利用已建的三个人群队列（1976年中年队列、1987年和2001年老年队列，总随访人年约10万）中吸烟行为及相关危险因素的重复测量及随访数据，采用队列研究和巢式病例对照研究设计，探讨中老年人戒烟与主要烟草相关疾病（冠心病、脑卒中、肺癌）的关系；运用文献分析和数学建模法筛选烟草成瘾机制相关的主要基因，集成和构建烟草成瘾基因评分体系，并依托其队列的DNA资源运用分子流行病学设计和高通量SNP检测技术在研究人群中验证是否存在烟草成瘾的易感基因及其综合评分的科学性；并引入生物信息学分析技术研究烟草成瘾易感基因及评分与国人吸烟行为及主要烟草相关疾病的关联，探讨烟草成瘾的可能机制，为其病因预防假说的建立和针对性（按戒烟易感评分分类）干预措施的制定提供基础数据。

There were a lot of strong evidence on the benefits of smoking cessation in the western studies, however prospective evidence on the association of smoking cessation and tobacco related mortality in China is scarce. Through the design of a prospective cohort study and a nested case-control study, we will try to examine the relationship between smoking, smoking cessation and tobacco related mortality, particularly coronary heart disease (CHD), stroke and lung cancer, in three Chinese cohorts with longterm follow-up (over a total of 100,000 person-years). We also investigate the association of tobacco smoking addiction related genetic polymorphisms and a summary score with smoking-related phenotypes by the methods of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and SequenomMassARRAY, and explore the mechanism of health preventive effect from smoking cessation and tobacco smoking addiction. The result of our present project will provide some strong evidences and basical database to make the stringent tobacco control measures, and to reduce financial burden and health lesion brought by tobacco related diseases.