The new study suggests people with blood type AB are 82% more likely to develop thinking and memory problems that can lead to dementia.
The study was supported by the National Institutes of Health and the US Department of Health and Human Services, among other organizations, and is published in the journal Neurology.
The type of blood we have depends on whether or not there are certain proteins - called antigens - in our red blood cells, and this blood type is passed down from our parents.
There are four main blood types: type A, type B, type AB and type O. Additionally, if a substance called Rh factor appears on the surface of the red blood cells, a person is considered to be Rh+ (positive).
Type O+ is the most common blood type, while AB- is the least common. But not all ethnic groups have the same proportion of blood types. For example, Hispanics have a high number of O blood types, while Asians have a high number of B blood types.
According to the authors of this latest study, led by Dr. Mary Cushman of the University of Vermont College of Medicine in Burlington, the blood type AB is only found in about 4% of the US population, yet people with this blood type were 82% more likely than other types to develop the thinking and memory problems that can lead to dementia.
And Medical News Today recently reported on a study that suggested men with blood type O have lower recurrence of prostate cancer.
'Findings highlight links between vascular issues and brain health'
To conduct their study, the researchers used data from a larger one called the REGARDS Study, which stands for the REasons for Geographic And Racial Differences in Stroke. This bit of research followed 30,000 people for around 3.4 years.
Of those involved in the study who did not have memory or thinking problems at the start, the researchers pinpointed 495 participants who developed thinking and memory problems or cognitive impairment during the course of the study. These participants were then compared with 587 people who did not have any cognitive difficulties.
The results show that those with blood type AB made up 6% of the group that developed cognitive impairment, compared with only 4% found in the population.
Commenting on their study, Dr. Cushman says:
"Our study looks at blood type and risk of cognitive impairment, but several studies have shown that factors such as high blood pressure, high cholesterol and diabetes increase the risk of cognitive impairment and dementia.
Blood type is also related to other vascular conditions, like stroke, so the findings highlight the connections between vascular issues and brain health."
The team also looked at blood levels of a protein that helps blood clot, called factor VIII, high levels of which have been linked to a higher risk of cognitive impairment and dementia.
Those in the study with higher levels of this protein were 24% more likely to develop thinking and memory problems during the study than those with lower levels. Additionally, participants with blood type AB had a higher level of factor VIII than people from all other blood types.
Though their findings are intriguing, Dr. Cushman cautions that "more research is needed to confirm these results."
In January of this year, MNT reported on a study that analyzed the popular blood type diet - a lifestyle plan that recommends eating and exercising in certain ways, depending on blood type.
"The way an individual responds to any one of these diets has absolutely nothing to do with their blood type and has everything to do with their ability to stick to a sensible [...] diet," said senior author Dr. Ahmed El-Sohemy.