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The Strange Link Between Blood Type and Cognitive Health
Margo Pierce
In recent years studies have uncovered a curious link between people's blood type and their brain
health: people with O blood type seem to have lower risks of developing cognitive difficulties as they
age compared with people with non-O blood types, that is A, B, or AB. People with the latter type
seem to fare worst in these studies.
But how exactly does this happen?
The link between blood type and brain health is not yet fully understood but scientists have some
ideas to explain the surprising findings. People with A, B and AB blood types are more likely than
people with O blood types to have cardiovascular problems, which can in turn have a negative impact
on brain health, says Kristine Alexander of the University of Vermont who has investigated the link in
a 2014 study published in Neurology.
The new information about blood type adds to the growing body of knowledge about the way the
circulatory system influences the processes of the brain.
"The things that influence your cardiovascular systems often have impacts all over your body because
it's the plumbing system," Alexander says. "Your blood system is what feeds your brain and cleans out
waste materials. If that's not functioning well, you're brain's going to eventually show signs of
deterioration."
In their study, Alexander and her colleagues looked at more than 30,000 Caucasian and African-
American individuals age 45 and older and measured their cognitive skills such as decision making,
short-term memory and learning. The researchers also tracked participants' health and examined
how many of them developed cognitive impairments for about three years. The results showed that
participants with the least common blood type AB, were 80 percent more likely to develop cognitive
problems during the study period than people with other blood types.
What is the blood-brain connection?
The four major blood types are determined by the presence or absence of A and B antigens on the
surface of the red blood cells. The most common blood type is O, and it doesn't have any of the
antigens. AB is the least common blood type and it has both of the antigens.
But blood cells aren't the only cells in the body with the A and B antigens. The antigens are also stuck
to the surface of proteins that help blood to clot, called von Willebrand factor and factor 8 proteins.
People with A, B and AB blood types have more of these proteins floating in their plasma, and might
therefore have higher risk of forming blood clots that lead to stroke and heart attack.
"Stroke is often caused when you get a blood clot that travels up and blocks circulation to a certain
part of your brain. That's the most obvious ways these things are tied together – your blood type is
linked to your risk of forming a blood clot, which increases your risk of having a stroke," says
Alexander.
"But I don't think that's the whole story," Alexander says. Blood type may have some influence on
brain health, but lifestyle poses a far greater risk. Unhealthy habits such as smoking, lack of exercise,
poor nutrition and conditions such as diabetes increase the risk for brain problems by a larger degree.
Blood type and dementia
Recently neuroscientists at the University of Sheffield found a relationship between blood types, the
volume of grey matter in various regions of the brain, and risk of dementia.
The researchers looked at the MRI scans of 189 healthy volunteers and found that people with A, B
and AB blood types "had smaller grey matter volumes in temporal and limbic regions of the brain,
including the left hippocampus, which is one of the earliest parts of the brain damaged by Alzheimer's
disease."
People with O blood type had more gray matter in the posterior portion of the cerebellum — in two
symmetrical clusters within the posterior ventral portions. The cerebellum is best known for its role in
fine-tuning muscle movements, balance and coordination, and it has not been associated with the
common forms of dementia in previous studies, but researchers can't rule out the possibility that a
smaller cerebellum may be implicated in cognitive impairment.
The brain naturally deteriorates with age, just as other organs in the body do, making the elderly
more liable to develop cognitive difficulties. Changes to the prefrontal cortex and the hippocampus
impact an older person's ability to learn, remember and perform complex mental activities.
Additionally, neurons and neurotransmitters can degrade or be lost.
"The findings seem to indicate that people who have an 'O' blood type are more protected against
the diseases in which volumetric reduction is seen in temporal and mediotemporal regions of the
brain like with Alzheimer's disease, for instance," says study co-author Matteo DeMarco of University
of Sheffield, who published the results in the June edition of Brain Research Bulletin.
'Don't panic'
Researchers are also quick to caution against globalizing their results. These are the first of what will
likely be many more interdisciplinary studies about brain health and blood type, Alexander says. And
a lot more research is needed to fully understand the big picture of the relationship between brain
diseases and blood types. In the meanwhile, Alexander has some practical advice for how to address
current and future findings that might cause some concern.
"Don't panic," she says. "You can't run out and change your blood type, but there are ways to reduce
your risk. It's like if you have a family history of something like breast cancer or heart attack. You
know to be a little more vigorous about getting check-ups and finding other ways that you can reduce
your risk."
Published by: August 7, 2015 by braindecoder.com
https://www.braindecoder.com/how-blood-type-affects-brain-health-1285605041.html