Alcohol consumption is differently associated with different stroke types

A systematic review and meta-analysis published today in BMC Medicine reports on an association between alcohol consumption and different types of stroke. Here, author Susanna C. Larsson tells us more about the study and the possible implications of these findings.

Despite advances in diagnosis, treatment, and prevention, stroke remains a leading cause of disability and death globally. Stroke is not a single entity but consists of different types with distinct clinical features, pathologies, etiologies, and prognoses.

Ischemic stroke accounts for the vast majority of all strokes and occurs when the blood flow to an area of the brain is obstructed. The remaining strokes are hemorrhagic stroke (intracerebral hemorrhage and subarachnoid hemorrhage), which is caused by bleeding in the brain.

Light and moderate alcohol consumption was associated with a respectively 10% and 8% lower risk of ischemic stroke. (…) High and heavy alcohol consumption was positively associated with risk of all stroke types.

Whether light-to-moderate alcohol consumption, usually defined as 1 to 2 drinks per day, lowers the risk of cardiovascular disease is a controversial topic. Moderate drinking has been beneficially associated with some potential cardiovascular risk factors (e.g., high-density lipoprotein cholesterol, insulin sensitivity, and fibrinogen levels) and with a reduced risk of ischemic heart disease. However, high alcohol consumption is associated with an increased risk of hypertension, which is a major cause of stroke.

We performed a systematic review and meta-analysis to summarize available evidence from prospective studies on alcohol consumption and risk of different stroke types. Our meta-analysis included 27 prospective studies conducted in Europe (ten studies), United States (nine studies), and Asia (eight studies).

Findings from our meta-analysis showed that light and moderate alcohol consumption was associated with a respectively 10% and 8% lower risk of ischemic stroke. Light and moderate drinking was not significantly associated with risk of intracerebral hemorrhage or subarachnoid hemorrhage.

High and heavy alcohol consumption was positively associated with risk of all stroke types. Heavy drinking was significantly associated with a respectively 14%, 67%, and 82% increased risk of ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage.

The take home message from this study is that for those who drink alcohol, the consumption should be no more than 1–2 drinks per day.

High-to-heavy alcohol consumption (>2 drinks/day) was more strongly positively associated with risk of stroke, particularly hemorrhagic strokes, in women than in men but the differences were not significant. The associations of different levels of alcohol consumption with different stroke types were generally similar in European, North American, and Asian populations.

The take home message from this study is that for those who drink alcohol, the consumption should be no more than 1–2 drinks per day. This study further showed that high and heavy alcohol consumption was more strongly related to risk of hemorrhagic strokes than ischemic stroke.

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