Tanner C M, Goldman S M, Aston D A, Ottman R, Ellenberg J, Mayeux R, Langston J W
Parkinson's Institute, Sunnyvale, CA 94089, USA.
Neurology. 2002 Feb 26;58(4):581-8. doi: 10.1212/wnl.58.4.581.
To test the hypothesis that cigarette smoking protects against the development of PD.
Smoking has been inversely associated with PD in many studies, but whether this reflects a biologic effect on the underlying disease process or merely confounding or selection bias remains uncertain.
The authors compared smoking histories in male twin pairs identified from the National Academy of Sciences--National Research Council World War II Veteran Twins Cohort. The amount of cigarettes smoked (in pack-years) was collected until the time of PD onset in the affected twin or until the time of death for the unaffected twin, whichever came first. Differences in pack-years smoked until PD onset and until 10 and 20 years before onset were compared using paired t-tests. Comparisons were made overall and stratified by zygosity and concordance for PD. To assess the role of shared environment, correlation for smoking behaviors was compared between pairs concordant and discordant for PD.
Detailed smoking histories were available for 113 twin pairs in which at least one twin had PD (discordant pairs: 43 monozygotic [MZ], 50 dizygotic [DZ]; concordant pairs: 10 MZ, 10 DZ). Within-pair correlation for ever smoking was high in MZ pairs (phi = 0.47, p = 0.001) but not in DZ pairs (phi = 0.007, p = 0.96). In 33 discordant MZ pairs and 39 discordant DZ pairs in which at least one twin had smoked, the twins without PD smoked more than their brothers smoked (32.5 vs. 22.7 pack-years, p = 0.026). This was more marked in the MZ pairs (37.1 vs. 25.3 pack-years, p = 0.077) than in the DZ pairs (28.6 vs. 20.5 pack-years, p = 0.17). A similar relationship was seen when smoking dose was calculated only until 10 years before PD onset, suggesting that the lower dose of smoking in the twin with PD was not the result of early, undiagnosed disease.
Within twin pairs, risk of PD is inversely correlated with the dose (in pack-years) of cigarette smoking. This effect is most pronounced in MZ twins, despite the high correlation for smoking. Because MZ twins are genetically identical and are similar behaviorally, this difference is unlikely to result from either genetic factors or environmental confounders. These results are compatible with a true biologic protective effect of cigarette smoking.
检验吸烟可预防帕金森病（PD）发生这一假说。
许多研究表明吸烟与PD呈负相关，但这是反映了对潜在疾病进程的生物学效应，还是仅仅是混杂因素或选择偏倚，仍不确定。
作者比较了从美国国家科学院-国家研究委员会二战退伍军人双胞胎队列中确定的男性双胞胎对的吸烟史。收集吸烟量（以包年计算），直至患病双胞胎出现PD症状时，或直至未患病双胞胎死亡时，以先发生者为准。使用配对t检验比较出现PD症状时、症状出现前10年和20年的包年吸烟量差异。进行总体比较，并按PD的同卵性和一致性进行分层。为评估共同环境的作用，比较了PD一致和不一致的双胞胎对之间吸烟行为的相关性。
113对双胞胎有详细的吸烟史，其中至少有一名双胞胎患有PD（不一致对：43对同卵双胞胎[MZ]，50对异卵双胞胎[DZ]；一致对：10对MZ，10对DZ）。MZ双胞胎对中曾经吸烟的组内相关性较高（phi = 0.47，p = 0.001），而DZ双胞胎对中则不高（phi = 0.007，p = 0.96）。在至少有一名双胞胎吸烟的33对不一致MZ双胞胎对和39对不一致DZ双胞胎对中，未患PD的双胞胎比其兄弟吸烟更多（32.5对22.7包年，p = 0.026）。这在MZ双胞胎对中更明显（37.1对25.3包年，p = 0.077），而在DZ双胞胎对中则不明显（28.6对20.5包年，p = 0.17）。仅计算PD症状出现前10年的吸烟剂量时，也观察到类似的关系，这表明患PD的双胞胎吸烟剂量较低不是早期未确诊疾病的结果。
在双胞胎对中，PD风险与吸烟剂量（以包年计算）呈负相关。这种效应在MZ双胞胎中最为明显，尽管吸烟相关性很高。由于MZ双胞胎基因相同且行为相似，这种差异不太可能是由遗传因素或环境混杂因素导致的。这些结果与吸烟具有真正的生物学保护作用相符。
