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Critique 190: Alcohol intake during middle age and later atherosclerosis – 11 August 2016

Carotid artery disease can be estimated by ultrasound from the thickness of the wall of the arteries (recorded as carotid artery intima/medial thickness, cIMT) and by evidence of atherosclerotic plaques within the carotid arteries. The association between alcohol intake and such lesions is unclear, as some studies show a positive association with cIMT and/or plaques while others show no association. Given that carotid disease relates to the subsequent risk of coronary artery disease, there is increasing use of carotid ultrasound measurements to help determine long-term risk.

The present large study from the UK provides valuable information by reporting the cross-sectional relation between alcohol consumption and cIMT as well as how the drinking pattern over 20 years in middle age may relate to cIMT later in life. While heavy alcohol intake was found to increase later cIMT measures, no clear differences were noted between subjects reporting abstinence and those reporting moderate drinking in middle age.

Forum reviewers considered this to be a well-done study. There were some concerns that only total average alcohol intake was considered, as there were no data on the type of beverage consumed, the pattern of drinking (binge versus regular moderate), whether the alcohol was consumed with food, etc., and there was an absence of data on diet, physical activity, adiposity, and other factors related to atherosclerosis. Further, only the thickness of the carotid artery was evaluated, and not the presence or absence of atherosclerotic plaques on the ultrasound readings.

Overall, current scientific data provide strong evidence that moderate alcohol consumption lowers the risk of most manifestations of cardiovascular disease; it appears to work through a combination of effects on lipids, inflammation, coagulation, fibrinolysis, glucose metabolism, and other paths. Further, heavy drinking is known to increase blood pressure, and is an important factor for developing hypertension (and a strong determinant of cIMT). The failure of the present study to find a significant association between moderate alcohol intake and later carotid thickness supports what has been shown in some, but not all, previous studies.

If indeed chronic alcohol use has little effect on atherosclerosis (using images from the carotids as an index of atherosclerosis in the coronary arteries and elsewhere in the body), it may indicate that the mechanisms for the protective effect of moderate alcohol consumption on cardiovascular disease are not so much related to preventing atherogenesis, but due primarily to the effects on coagulopathy. And it is known that clot formation within the arterial wall is often the precipitating event for an acute myocardial infarction or other cardiovascular event.

Reference: Britton A, Hardy R, Kuhf D, Deanfield J, Charakida M, Bell S. Twenty-year trajectories of alcohol consumption during midlife and atherosclerotic thickening in early old age: findings from two British population cohort studies. BMC Medicine 2016l;14:111. DOI 10.1186/s12916-016-0656-9.

For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.
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