New research identifies alcohol risk factors for acute stroke

• Participants included people from high, middle and low-income countries, with different levels of education and cardiovascular risk

• Heavy and moderate alcohol consumption is associated with an increased chance of stroke

• Studies have shown that there is no compelling link between low alcohol consumption and stroke, but the risk varies from world to world

• The study also assessed whether different types of alcohol were associated with stroke risk

A global study co-led by the University of Galway on the causes of stroke found that heavy and moderate alcohol consumption was associated
with an increased chance of stroke.

The study also found no link
between low levels of drinking and stroke.

THE INTERSTROKE STUDY LOOKED AT THE ALCOHOL CONSUMPTION OF NEARLY 26,000 PEOPLE WORLDWIDE, WITH A QUARTER OF THEM DRINKING REGULARLY AND TWO-THIRDS OF THEM NOT
DRINKING.

The study involved people from diverse ethnic backgrounds in 27 countries, including Ireland and the United Kingdom
.

The results were published in neurology, the most read and cited journal
of neurology.

Professor Martin O'Donnell, Professor of Neurovascular Medicine at the University of Galway and Consultant Stroke Physician at Galway University Hospital, co-led the international INTERSTROKE study
in collaboration with Professor Salim Yusuf of the Institute of Population Health at McMaster University, Canada.

Professor O'Donnell said: "Stroke is the leading cause of
death and disability worldwide.
Every year, around 7,500 Irish people suffer a stroke, of which about 2,000 die
.
An estimated 30,000 people in Ireland have been disabled
by stroke.
The INTERSTROKE study aims to study the main risk factors for stroke in different parts of the world and inform prevention approaches at the population level
.
In this paper, we focus on the role of
alcohol intake and stroke risk.

"While it is well known that high alcohol intake increases stroke risk, there is some uncertainty
about whether low-moderate alcohol intake affects stroke risk and whether the association between alcohol intake and stroke varies by region and population.
"

The study was conducted on a large scale in 27 countries
.

Strokes can occur
as a result of blood clots (ischemia) or bleeding (intracerebral hemorrhage).

Professor Andrew Smyth, Professor of Clinical Epidemiology at the University of Galway, Director of the Clinical Research Facility at the Galway Health Research Council and Consultant Nephrologist at Galway University Hospital, was the principal investigator
of the study.

Professor Smith said: "Overall, our findings suggest that high and moderate alcohol intake is associated with an increased chance of stroke, while we found no compelling link
between low intake and stroke.
"

"However, the impact of alcohol intake is complex as it is linked to
socioeconomic factors such as education and many lifestyle factors, including smoking, diet and physical activity.
" The potential impact of alcoholism, often classified as "binge drinking," is an important factor
to consider.
The adverse risk of drinking seven glasses of wine per day per week may be greater
than drinking one drink per day per week.

"In this study, we also looked at the differences
in different types of alcohol.
Major beer consumption was associated with a 21% increased risk of stroke; The proportion of intracerebral hemorrhages is significantly higher (73%)
.
The main wine consumption was not associated with the risk of stroke – there was no increase or decrease
.
This may reflect differences in the risk of different types of alcohol, or differences in consumption patterns in social
contexts.
”

INTERSTROKE'S STUDY INCLUDED AN ANALYSIS
OF PEOPLE WHO HAD PREVIOUSLY DRUNK BUT HAD QUIT.
The study found that they did not have an increased
risk of stroke.

Other findings from the study include:

• People who drink regularly have a 14% increased chance of all strokes and a 50% higher chance of developing a cerebral hemorrhage (a stroke caused by bleeding), but not an increase
  in the chance of ischemic stroke (a stroke caused by a blood clots).
  

• Severe intermittent or formerly known as "binge drinking" – defined as drinking more than 5 drinks at least once a day – was associated with a 39% increase in the incidence of all strokes; ischemic stroke increased by 29%; Cerebral hemorrhage increased by 76%.
  
  

• High alcohol intake — defined as more than 14 drinks per week for women and 21 drinks per week for men — was associated
  with a 57 percent increase in stroke.
  

Professor Michelle Canavan, Senior Professor of Geriatric Health and Consultant Geriatrics, added: "While most previous studies have been done in high-income countries with limited cultural diversity, the global INTERSTROKE study took a different approach, including participants from high, middle and low income countries with varying
levels of education and cardiovascular risk status.

"Worldwide, there are differences in alcohol intake by gender, age, social class, education level and occupation, as well as differences
in the type of alcohol consumed and how it is consumed.

"In Western Europe and North America, current alcohol consumption is associated with a reduced risk of stroke, but in India and South America, the risk of stroke is increased
.
Alcoholics had the highest increased risk of stroke in South America, Africa, and India, and in China and Southeast Asia
.
Therefore, targeted interventions to manage high intake at the population level may help reduce stroke risk, especially for
men in these areas who are more likely to drink heavily.
”