A new study that investigated the causes of stroke and discovered a link between high and moderate alcohol consumption and an increased stroke risk.
The global study, which was co-led by the University of Galway, included individuals from high, middle and lower income countries, with varied levels of cardiovascular profiles and education.
This research was part of the INTERSTROKE study, which is one of the largest international studies of risk factors for stroke.
Alcohol consumption of close to 26,000 individuals worldwide was examined, one quarter of those were current drinkers and two-thirds were teetotal.
As mentioned the study involved individuals from a range of backgrounds across 27 countries, including the UK and Ireland.
Co-leader of the study professor Martin O’Donnell, says: “Stroke is a leading cause of death and disability globally.
“Each year, approximately 7,500 Irish people have a stroke, and around 2,000 of these people die.
“An estimated 30,000 people in Ireland are living with disabilities as a result of stroke.
“The INTERSTROKE study was designed to look at the key risk factors for stroke in different regions of the world, to inform approaches to population-level prevention. In this paper, we focused on the role of alcohol intake and stroke risk.
“While high alcohol intake is known to increase stroke risk, there is some uncertainty about whether low-moderate alcohol intake affects stroke risk and whether the association of alcohol intake with stroke varies by region and population.”
A large scale examination of these associations was carried out in this study.
Professor Andrew Smyth, lead researcher of the study, says: “Overall, our findings indicate that high and moderate intake of alcohol were associated with increased odds of stroke, while we found no convincing link between low intake and stroke.
“However, the effects of alcohol intake are complex as they are linked with socioeconomic factors such as education and many lifestyle factors including smoking, diet and physical activity.
“The potential impact of what is commonly classed as ‘binge drinking’ is important to consider. The adverse risk of having seven drinks one day per week are likely to be greater than having one drink each day per week.
“In this study we also looked at the differences between types of alcohol. Predominant beer consumption was linked with a 21% increase in risk of stroke; this was significantly higher (73%) for intracerebral haemorrhage.
“Predominant wine consumption was not linked with risk of stroke – there was no increase or decrease. This may reflect a difference in risk by type of alcohol, or may reflect differences in the social context of consumption patterns.”
Analysis of people who had previously been drinkers but since stopped was included in the INTERSTROKE study, however, the study found they were not at increased risk of stroke.
The study found that current drinkers were associated with a 14 per cent increase in odds of all stroke, and 50 per cent increase in risk of intracerebral haemorrhage, but no increase in risk of ischaemic stroke.
Heavy episodic, defined as more than 5 drinks in one day at least once a month, was linked with a 39 per cent increase in all stroke; 29 per cent increase in ischaemic stroke; and 76 per cent in intracerebral haemorrhage.
Additionally, high alcohol intake, defined as more than 14 drinks per week for females and 21 drinks per week for males, was linked to a 57 per cent increase in stroke.
Professor Michelle Canavan, consultant geriatrician, says: “Most previous research was completed in high-income countries, with limited cultural diversity whereas the global INTERSTROKE study took a different approach by including participants from high, middle and lower income countries with varying levels of education and cardiovascular risk profiles.
“Worldwide there are differences in alcohol intake by gender, age, social class, education and occupation, as well as differences in type of alcohol consumed and the pattern of drinking.
“Current drinking was linked with reduced risk of stroke in Western Europe and North America, but increased risk of stroke in India and South America.
“The greatest increases in stroke risk were seen for binge drinkers in South America, Africa and India and with those who have high levels of alcohol consumption in China and South East Asia.
“Therefore, targeted interventions to manage high intake at population level may help reduce stroke risk particularly for males in these regions who are more likely to binge drink.”
