Does blood type affect your memory?

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People with blood type AB—roughly 3 per cent of Australians—are nearly twice as likely as those with other blood types to develop the kinds of memory difficulties that precede dementia, according to new research appearing in Neurology.

Wait. What? Unfortunately, you read right. A team of American researchers combed through several years of health data from a sample of more than 30,000 people.

Here’s what they found: Compared to those with all other blood types, the AB people were 82% more likely to develop the kinds of cognitive impairments that lead to more serious memory conditions, like dementia.

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While the mechanisms at work here aren’t clear, there’s some evidence that different blood types are linked to specific genetic variations—including one that has to do with your blood’s clotting proteins, explains study coauthor Dr Mary Cushman, a haematologist at the University of Vermont in the US.

Cushman says these blood proteins may change your risk for some vascular (blood flow) diseases. And because your brain needs plenty of blood—and the oxygen in your blood—to operate properly, these clotting proteins could help explain her team’s findings. (Research has also linked certain blood types to higher or lower rates of heart disease, stroke, blood clots, and some rare forms of cancer, Cushman adds.)

So should you freak out if you're AB? Not yet, Cushman says. “The association we saw was relatively small and requires confirmation,” she stresses.

And while the risk for memory problems jumped 82% among people with AB blood compared to others, their overall risk for developing these problems was still pretty low.

Cushman says a healthy lifestyle (exercising regularly, not smoking) is your best defence against age-related memory issues. She also recommends keeping a close eye on your blood pressure, and staying “cognitively active” by reading, playing games, and trying new activities.

Bottom line: While the research is surprising, your blood type is a relatively small factor when it comes to your risk for brain diseases like dementia.

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