More than 120 years have passed since the discovery of blood groups, but scientists still do not know why they are different in different people. But back in the mid-20th century, scientists discovered that different blood groups are associated with different diseases. According to some scientists, the evolutionary meaning of the emergence of different blood groups is precisely to protect people from certain diseases. It is now known that the risk of developing certain types of cancer, a tendency to cardiovascular diseases, severe malaria, ulcers, ruptured Achilles tendons, and even a tendency to alcoholism depend on the blood group. A recent study has shown that even the risk of stroke depends on the blood group.
Scientists have discovered that blood type affects stroke risk. Photo source: risk.ru
What are blood groups and how do they differ
For centuries, scientists have tried to save people with blood transfusions, but until the 20th century, this procedure most often ended in the death of the patient. The situation changed only after blood groups were discovered. As it turned out, it was all about red blood cells, or more precisely, the molecules that are on their surfaces.
Red blood cells of each group have different molecules on their surface. It is these molecules that determine a person's blood group. The key molecules are A and B. They can be found either separately on the surface of red blood cells (“A” and “B”) or together – “AB”. Sometimes they are absent altogether (the group is designated as “O”). As a result, there are four blood groups: “A”, “B”, “AB” and “O”. It is interesting that during life, the blood group can change, although this happens extremely rarely.
Blood type is determined by molecules on the surface of red blood cells. Photo source: wikipedia.org
In addition, there are certain differences within the main blood groups. For example, there is a positive and negative Rh factor, which depends on the presence of the D antigen, and there are other differences.
Which blood group is associated with an increased risk of stroke
Scientists have found that people with blood type A are more likely to have a stroke before age 60 than other people. They came to this conclusion based on data from 48 genetic studies, which involved a total of 17,000 people with stroke and 600,000 people without stroke. All people were aged 18 to 59.
As a result, the scientists were able to identify two regions in the genome that were closely associated with an early risk of stroke. One of these regions coincided with the region where the genes encoding blood type are located. Gene analysis showed that people with the gene encoding blood type A1 (one of the variations of blood type A) had a 16% increased risk of stroke compared to other people.
The highest risk of stroke is in people with blood type A. Source: gemotest.ru
But in people with the gene encoding blood group O1, the risk of stroke, on the contrary, is reduced by 12 percent. In people with blood group B, the probability of stroke is about 11 percent higher, and at any age – both before and after 60. In addition, groups A and B are also associated with a higher risk of blood clots in the veins. The authors of the work report this in the journal Neurology.
Why does blood type affect stroke risk
Scientists cannot yet name the reason why one blood type has an increased risk of stroke, while another has a decreased risk. But most likely, this is due to clotting factors – platelets and cells lining blood vessels, as well as other proteins that play a certain role in blood clotting.
It must be said that blood type A is generally one of the most “problematic”. In addition to the risk of stroke, people with this blood type have an increased risk of alcoholism. In addition, the risk of pancreatic cancer and leukemia, cardiovascular and some other diseases is increased. Scientists have not yet found an explanation for this.
The risk of stroke does not depend on blood type as much as on some other factors. Photo source: ria.ru
Fortunately, the risk of stroke in blood group A is slightly increased. There are many other factors that increase the risk of stroke much more. For example, these include constant lack of sleep, poor nutrition, bad habits, or a sedentary lifestyle. Therefore, by eliminating other risk factors, you can not worry much about stroke.
Another interesting conclusion that scientists made during the study is that the risk of stroke in people with blood group A is significantly reduced after the age of 60. Of course, this does not mean that after 60 years, something happens to the circulatory system of such people, as a result of which it becomes more protected from stroke. It's just that in other people at this age, the risk of stroke increases significantly, that is, much more than in people with blood group A.
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This is most likely due to the fact that strokes at an early age have a different mechanism compared to strokes that occur at a later age. However, scientists will need additional research to make a final conclusion.