Several previous studies have identified lifestyle changes individuals can make to prevent memory loss, such as keeping stress and blood sugars low, and not smoking. But a new study pinpoints a potential risk factor for memory loss that we can do nothing about: our blood type.
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 percent of the US population, yet people with this blood type were 82 percent more likely than other types to develop the thinking and memory problems that can lead to dementia. Conversely, they note that previous studies have shown that people with blood type O have a lower risk of heart disease and stroke, which are factors that can increase risks for memory loss and dementia.
‘Findings highlight links between vascular issues and brain health’
To reach their conclusions, the researchers used data from a larger study called the REGARDS Study, which stands for the REasons for Geographic And Racial Differences in Stroke. The team collected data from 30,000 participants enrolled in the REGARDS study, following them for an average of 3.4 years.
Of those involved in the study who did not have memory or thinking problems at the start, the researchers identified 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 percent of the group that developed cognitive impairment, compared with only 4 percent found in the population.
“Blood type is also related to other vascular conditions, like stroke” says Dr. Cushman, offering one potential explanation for the results. “[The] findings highlight the connections between vascular issues and brain health,” he adds.
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 percent 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.”