Study Uncovers Link between Blood Type and Risk of Cognitive Decline

Many factors impact brain health, from genetics to sleep quality. And now a new landmark study has found that blood type also may affect cognitive function as we age.

Indeed, researchers at the University of Sheffield in England found that those with an O blood type have more gray matter in their brain, which helps ward off diseases such as Alzheimer's, than those with A, B or AB blood types.

"In all likelihood the biology of blood types influences the development of the nervous system," said Professor Annalena Venneri in a written statement. "We now have to understand how and why this occurs.”

Gray matter, largely composed of neuronal cell bodies, serves to process information in the brain. As we age, a reduction of gray matter volumes typically occurs.

Venneri and other researchers analyzed the results of 189 MRI scans from healthy volunteers. They calculated the volumes of gray matter within the brain and then looked at the differences based on blood type.

The results, published in the Brain Research Bulletin, show that individuals with an O blood type have more gray matter in the posterior proportion of the cerebellum. In comparison, those with A, B or AB blood types had less gray matter in parts of the brain including the left hippocampus, which deals with the formation of long-term memories.

But researchers said more studies are needed to figure out what other biological mechanisms may be at play.

The results from the new study mirrored 2014 research that also looked at blood type and brain function. That study, by researchers at the University of Vermont, found that those with the rare AB blood type, present in less than 10 percent of the population, have a higher than average risk of cognitive problems as they age.

So what if you don't have the O blood type? Don't panic, experts say. Other studies suggest that both meditation and a healthy diet can help grow gray matter.