The Blood Type That Could Increase Your Risk Of Memory Problems

Knowing your blood type is important for so many reasons, including ensuring you receive the right blood should you ever require a transfusion. But as more research is carried out, it's becoming increasingly clear that blood type can also tell us about certain conditions to which we might be predisposed, and it seems those with type AB blood could be at a higher risk of experiencing mental decline as they age. A study conducted in 2014 appeared to show a significantly increased risk of thinking and memory problems for those with this blood type, though other research has thrown the findings into question.

It's sort of unsettling to think that, prior to the 1900s, doctors essentially thought all blood was the same. As a result, plenty of people died after receiving the wrong blood type during transfusions. Thankfully, that's become a thing of the past, but just because we've determined that blood does in fact come in different varieties — and is one of the most important genetic characteristics – doesn't mean there aren't several new unsettling facts to arise out of this discovery. For one thing, those with a certain blood type could be at greater risk of a painful death, while another blood type has been shown to increase risk of stroke.

Still, it's better that we're aware of such things, as it can help greatly when it comes to preventative treatment. That's an especially relevant concern when it comes to the blood type that could increase your risk of memory loss. Cognitive decline is surely one of the most terrifying potentialities of aging, and as of yet, there is no known cure for the various forms of dementia. But there are things that can be done to help slow mental degeneration, so knowledge really is power.

Human blood is grouped into four main types: A, B, AB, and O. There are also positive and negative variations of each, and some of these groups are rarer than others, with AB negative representing the rarest of them all. Just 0.6% of the U.S. population have AB negative blood type while 3.4% have AB positive. Unfortunately, those who do have this blood type may be more likely to experience cognitive problems as they age.

A 2014 study published in Neurology, the medical journal of the American Academy of Neurology, found that people with AB blood were 82% percent more likely to experience cognitive and memory problems that could precede dementia than people with other blood types. This was a comprehensive study, too, following 30,239 individuals aged 45 years and older in the United States for an average of 3.4 years. 495 participants were found to have developed thinking and memory problems or cognitive impairment after starting the study with no such issues. This group was then compared to 587 people who did not show any signs of cognitive problems, where it was discovered that 6% of those with such problems had type AB blood. As the researchers noted, that percentage is higher than the 4% found in the general population.

As well as highlighting a potential link between blood type and the risk of cognitive decline, the study also showed that participants with high levels of the protein factor VIII were 24% percent more likely to experience thinking and memory problems. As you might expect, those with AB blood were found to have higher levels of factor VIII on average — but there could be something else going on here, as research conducted just a year after the Neurology study seemed to contradict its findings.

A 2015 study published in PLOS One seemed to contradict evidence from the 2014 study. Researchers used information from a database of more than 1.6 million blood donors from 1968 in Sweden and 1981 from Denmark. They identified 3,615 cases of Alzheimer's disease, 1,842 cases of vascular dementia, and 9,091 cases of unspecified dementia. Crucially, the study showed there was no association between ABO blood group and the risk of Alzheimer's disease, vascular dementia, or unspecified dementia, leading the researchers to conclude that there was no evidence for ABO blood type increasing the risk of dementia.

However, this might be partly explained by the fact that blood type O has been shown to be associated with a lower risk of conditions thought to lead to dementia. A 2022 study, also published in the journal Neurology, found that people with blood type A were at a 16% higher risk of experiencing a stroke. But the researchers also found that those with type O blood were at a 12% lower risk. Strokes (as well as related conditions like hypertension and obesity) are a factor that can contribute to an increased risk of memory loss and dementia, suggesting that rather than being more disposed to cognitive decline, those with type AB blood might be more at risk due to their relatively higher risk of stroke. Indeed, the researchers in the 2014 study noted that the ABO blood group is already associated with conditions such as coronary heart disease, stroke, and venous thromboembolism, which suggests the results showing an increased risk of cognitive decline might well have more to do with a predisposition to other conditions. As more research is carried out, we'll learn more about the link between blood type and dementia, but it's definitely worth bearing in mind for those with this extremely rare blood.