Drinking and Stroke Risk
Let's face it, more than an occasional drink is consumed on Seabrook from time to time - at least at our home. There has been and will continue to be the question of how much is too much when it comes to alcoholic beverage consumption. The State is about to change the legal limit of blood alcohol and the definition of driving under the influence making it more easier to be classified as under the influence. There are no studies that I am aware of that relate the blood or breath analyzer alcohol level with risk of heart disease, cancer or stroke the big three concerns we have with regard to healthy aging. However, there are some studies that relate the amount of alcohol consumed per day and the risk (chance) of having a stroke.Latest Study
An analysis of the world's literature on the question of does drinking influence the incidence of stroke was recently published from Tulane University. The results are instructional. What was examined was the effect of alcohol intake and whether people had the two classifications of total stroke, ischemic or hemorrhagic. All of the studies included a reference group of non-drinkers to determine if alcohol might provide protection against stroke. The effect of gender was also examined.The Results
Drinking alcohol is related to the incidence of stroke. In general the more alcohol that is consumed on the excessive side the greater the risk for the development of a stroke. This is true of both types of stroke (ischemic and hemorrhagic). However there is a caveat that if little or so called moderate amounts of alcohol are consumed there is some protection against an ischemic stroke. What is moderate consumption? Less than 1 drink per day is associated with protection against an ischemic stroke compared to no drinks per day or more than 2 drinks per day. One to 2 drinks per day protects against ischemic stroke but not hemorrhagic. If one drinks 5 or more drinks per day it is high risk behavior with regard to both types of strokes (and other things as well!). There is evidence that women benefit more than men from moderate alcohol consumption.Why Is This So?
Alcohol in excess (more than 2 drinks a day) can contribute to hypertension that we all know contributes directly to stroke. Alcohol can cause certain heart problems that also contribute to stroke (atrial fibrillation, cardiomyopathy for example) There is also evidence that alcohol can inhibit coagulation and this might explain why alcohol tends to directly relate to hemorrhagic stroke (intracerebral hemorrhage, for example). On the other hand, this same coagulation effect seems to protect against ischemic strokes (transient ischemic attacks, for example) when alcohol is taken in moderation. Also alcohol raises the good cholesterol (high-density lipoprotein) and this is associated with less stroke risk.What Do We Still Not Know?
It is still not clear whether one form of alcohol (beer versus wine versus bourbon etc) is better or worse. It is also not completely clear whether one drink means one's favorite, cocktail, one glass of wine or one beer or slightly more beer and wine. The equivalency and volume of the alcohol is not fully established. However, it is now quite clear that a little alcohol maybe one drink a day is OK, maybe even good, but this is clearly a case where too much of a good thing is bad! Limit the alcohol to one or two drinks a day to keep the risk of stroke lower.Alcohol use may increase the risk of hemorrhagic stroke.
Now that Thanksgiving is here, it is important to remind ourselves of the dangers of seasonal binge drinking. The National Institute on Alcohol Abuse and Alcoholism (NIAAA) warn about the myths around alcohol use and give advice on how to drink safely during the holidays.
Up to one drink per day for women and two drinks per day for men counts as moderate drinking. According to the NIAAA, moderate drinking seems to lower the risk of heart disease, ischemic stroke, and diabetes.
However, consuming alcohol in high amounts remains highly dangerous. A large number of Americans die of alcohol-related incidents every year, making alcohol the fourth leading preventable cause of death in the United States.
New research looks at the impact of alcohol on the risk of developing stroke.
Analyzing the link between alcohol and stroke
Researchers from the Karolinska Institute in Sweden and the University of Cambridge in the United Kingdom examined associations between alcohol consumption and different types of stroke.The study consisted of a systematic review and meta-analysis of existing studies. Researchers looked at 25 prospective studies containing data on ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage.
Studies included data from The Cohort of Swedish Men and the Swedish Mammography Cohort, summing up a total of 18,289 ischemic stroke cases, 2,299 intracerebral hemorrhage cases, and 1,164 cases of subarachnoid hemorrhage.
Levels of alcohol consumption were evaluated using patients' self-reporting. Participants answered a series of questions using a questionnaire or an interview.
Using standardized measures of alcohol, alcohol consumption was divided into four categories: light drinking (one daily drink or less), moderate drinking (one to two drinks per day), high drinking (two to four drinks per day), and heavy drinking (more than four drinks daily).
The study adjusted for variables such as age, sex, smoking, body mass index (BMI), and diabetes.
Results were published in the open-access journal BMC Medicine.
Alcohol may increase the risk of hemorrhagic stroke
The meta-analysis looked at two different types of stroke: ischemic and hemorrhagic.Ischemic stroke is the most common type of stroke. It is caused by a blood clot blocking the flow of blood and oxygen from reaching the brain.
A hemorrhagic stroke occurs either when an aneurysm bursts, or a weakened blood vessel leaks. The result is bleeding either inside the brain, causing an intracerebral hemorrhage, or, less commonly, bleeding between the brain and the tissue covering it, causing a so-called subarachnoid hemorrhage.
The study revealed that light and moderate alcohol consumption seemed to lower the risk of ischemic stroke, but it had no impact on the risk of developing hemorrhagic stroke.
Dr. Susanna Larsson, lead author of the study, explains why this may be:
"Previous research has found an association between alcohol consumption and lower levels of fibrinogen - a protein in the body which helps the formation of blood clots. This may explain the association between light to moderate alcohol consumption and lower ischemic stroke risk."
However, drinking may, in fact, increase the risk of hemorrhagic stroke. This is more apparent when looking at the heavy drinking category.
"Our results showed that heavy drinkers were about 1.6 times more likely to suffer from intracerebral hemorrhage and 1.8 times more likely to suffer from subarachnoid hemorrhage. The association between heavy alcohol consumption and these two types of stroke was stronger than that for ischemic stroke."Therefore, even if moderate drinking may have a beneficial effect by lowering the risk of ischemic stroke, the disadvantages might outweigh the benefits.
Dr. Susanna Larsson
"The adverse effect of alcohol consumption on blood pressure - a major risk factor for stroke - may increase the risk of hemorrhagic stroke and outweigh any potential benefit," Dr. Larsson mentions.
Strengths and limitations of the study
Dr. Larsson points out that the large sample size included in the analysis allowed for accurate associations between a wide range of alcohol consumption patterns and patient subgroups."This is the first study that combines the results from all available prospective studies on alcohol consumption and risk of hemorrhagic stroke subtypes," Dr. Larsson says.
However, some of the studies included in the meta-analysis were small in sample size, which means that the positive effects of light to moderate alcohol use may have been overestimated.
Also, the meta-analysis could not use the same categories of alcohol consumption across all the studies, as the authors lacked individual patient data.
Finally, as this is an observational study, it cannot show causality between using alcohol and the risk of developing different kinds of stroke.
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