Carotid arteriosclerosis in identical twins discordant for cigarette smoking.

Abstract

From a nationwide twin panel, identical twin pairs with highest discordance in cigarette smoking were selected for a study of arteriosclerosis (49 pairs with a mean age of 52 years). Smoking history was obtained in 1975, 1981, and 1986. The mean life-long smoking dose of the smoking cotwins was 20 package-years. The smoking and nonsmoking cotwins had similar systolic and diastolic blood pressures, total plasma cholesterol level, body mass index, and some psychosocial factors; the only difference was found in use of alcohol, which was greater among smoking cotwins. Duplex sonography of carotid arteries was performed. Carotid artery stenoses (narrowing of area of the lumen with 15-60%o) were found in nine pairs: in nine smoking twins and in two of their nonsmoking cotwins (p=0036). The total area of carotid plaques was 3.2 times larger in smoking cotwins (p<0.001). The thickness of the inner layer of carotid arteries was more marked in smoking cotwins (p<0.001). The size of plaques and the degree of inner layer thickening correlated with the dose of smoking (NS). The association of smoking with carotid arteriosclerosis was highly significant even after the adjustment for age, total plasma cholesterol level, diastolic blood pressure, and body mass index in multiple logistic regression analyses. (Circulation 1989;80:10-16) S moking is associated with arteriosclerotic lesions. The relation has been most consistently shown in the abdominal aorta and in major arteries of the lower limbs, but in coronary arteries, the relation has been less consistently shown.4,9-11 There are only a few reports on the relation between smoking and atherosclerosis in cerebral arteries.12 In contrast to other epidemiologic evidence, studies of smoking-discordant twin pairs have not shown differences in manifest coronary heart disease in the smoking and nonsmoking cotwins.'3-19 These findings have suggested to critics that the association of smoking and coronary heart disease is noncausal.20-22 Studies of mortality among smoking-discordant pairs found only a slightly increased risk of death in the smoking cotwin compared with the nonsmoking cotwin.7,23 There-

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Population-Based Twin Registries: Illustrative Applications in Genetic Epidemiology and Behavioral Genetics from the Finnish Twin Cohort Study

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Lower insulin sensitivity as an independent risk factor for carotid wall thickening in normotensive, non-diabetic, non-smoking normal weight and obese premenopausal women

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