Alexander E. Merkler, MD 
Jones SB, Loehr L, Avery CL, Gottesman RF, Wruck L, Shahar E, and Rosamond WD. Midlife Alcohol Consumption and the Risk of Stroke in the Atherosclerosis Risk in Communities Study. Stroke. 2015

The association between alcohol use and stroke has been well studied. Based on prior reports and meta-analyses, light alcohol consumption is thought to be protective against ischemic stroke whereas heavy alcohol consumption may increase the risk of ischemic stroke. On the other hand, alcohol consumption only seems to increase the risk of intracerebral hemorrhage (ICH). As the authors point out, previous studies had multiple limitations including lack of information regarding previous alcohol use, socioeconomic data, or were retrospective analyses. 

The current study by Jones et al, evaluates the relationship between mid-life alcohol use and stroke using the Atherosclerosis Risk in Communities Study (ARIC). More than 15,000 patients were enrolled in ARIC, a prospective study of middle aged adults, performed at four socioeconomically diverse locations in the United States. Patients were followed for up to 25 years. In this study, patients included had no history of prior stroke and either were current alcohol consumers or lifetime abstainers. Thus, patients who were former alcohol consumers were excluded from the study. Alcohol use was assessed using questionnaires at the initial enrollment visit. Alcohol use was divided into 4 groups: never drinkers, light drinkers (less than 3 drinks / week), moderate drinkers (4-17 drinks/week) and heavy drinkers (>18 drinks/week).

Of the 12,000 ARIC subjects included in the analysis, more than one third were light drinkers, one-third reported lifetime abstinence from alcohol, and just 5% were heavy alcohol consumers. After adjustment for confounders, any amount of alcohol use was neither harmful nor protective against the development of ischemic stroke, which does not support the classic “J-shaped” relationship of alcohol use and risk of ischemic stroke. There was a trend that light alcohol consumption may be protective against ischemic stroke in white women and harmful in black men, but the confidence intervals were wide and crossed 1. On the other hand, moderate-to-heavy alcohol use was significantly associated with ICH (HR 1.99, 95% CI

The main limitation is that alcohol consumption was only evaluated at one time during the study – the initial visit. Thus, it is very possible that each patient’s alcohol consumption varied as the study progressed. Other limitations include the lack of knowledge regarding type of alcohol consumed, the reliance of questionnaires, and the fact that the study power was too low to detect significant differences in certain study subgroups such as heavy alcohol use.

Overall, the results of this large, prospectively gathered, heterogeneous population show neither a protective nor harmful effect of alcohol consumption on ischemic stroke risk. On the other hand, the results are consistent with prior reports showing a significant association between moderate-heavy alcohol consumption and development of ICH. Future research will be necessary to tease out the relationship between alcohol use and ischemic stroke.