Wednesday, February 17, 2016

What About That Negative Blood?

Every once in a while, I get an A&P student who expresses the concept of a negative Rh blood type as "having negative blood"—along with the connotation that having this blood type has a negative health impact.

We do not ordinarily think about red blood cell types such as A, B, AB, O, Rh+/-, or others, as being "bad for you" or even "good for you" healthwise. We most often think of them simply as different "flavors" of RBCs present in the human population.

Oh yeah, there are specific situations in which have a particular blood type can have significant health consequences. If you need an organ or tissue transplant—especially a blood donation—having the same RBC type as the available donor supply is "good for you." The lack thereof, then, is "bad for you" to at least some degree. Just like being tall can be bad for you when going through a low doorway.

Likewise, we all know there are health risks associated with a Rh- mother carrying an Rh+ fetus—especially the situation is not identified or if precautions are not taken.  But it's not like the Rh- type itself has a direct health impact on the person with that type.

However, such a view may be a bit more complex than it first seems.  Research continues to confirm that having a particular RBC type may affect your risk for certain health conditions.

For example, a little over a year ago, research published in the journal Neurology found that adults with type AB blood were at an increased risk of cognitive impairment compared to type O.  Of course, much more work needs to be done to establish a potential mechanism for this phenomenon. But it does give some evidence that the idea of certain blood types having health consequences may be true.

Other studies have suggested these links:

  • Type O may be linked to depression, anxiety, low (female) fertility

  • Type O and/or A may be linked to attention-deficit disorder (ADD) in children

  • Type B may be linked to a lower risk of ADD in children

  • Type A may be linked to obsessive-compulsive disorder and stomach cancer

  • Type A, B, and AB may be linked to heart disease and abnormal blood clotting

What can we use from this in teaching undergraduate A&P?

  • Another interesting aside to throw into an exploration of blood types to "liven up" the conversation a bit to motivate students.

  • Consider using a diagram of the actual ABO markers to show what's involved at the cellular level—and their similarity to each other.

  • One may want to mention that blood types may become a factor health professionals may look at when assessing health risks in patients

  • A classroom discussion on possible mechanisms of a blood-type—health risk could be interesting and useful. This could lead to some great insights about methods of scientific discovery. For example, what's the difference between correlation and cause? How confident should we be in one study?

    • Consider leading the discussion toward exactly what you want your students to know about blood types and health (e.g., blood donors and recipients, erythroblastosis fetalis, etc.)

Want to know more?

Blood Type Matters for Brain Health

  • A. Anderson and V. Stern. Scientific American MIND January 1, 2015
  • Brief article explains discovery that people with AB blood type are at higher risk for age-related cognitive decline. Also lists some of the other blood-type links I mentioned above.

ABO blood type, factor VIII, and incident cognitive impairment in the REGARDS cohort

  • K. S. Alexander, et al. Neurology September 30, 2014 vol. 83 no. 14 1271-1276 
  • doi: 10.1212/WNL.0000000000000844
  • Original research article about the discovery about AB blood type and brain health.

Type O blood may be a fertility barrier

  • New Scientist. 10:15 26 October 2010
  • Brief article in plain English.

Yes, your blood group DOES affect your health

  • J. Naish Daily Mail 22 February 2011
  • Brief article includes some interesting historical facts.

Your Blood Type May Boost Your Heart Risk, Study Finds

  • S. Reinberg HealthDay Aug. 14, 2012
  • Brief article on link between blood type and heart disease

Blood photo: M. Osuchowicz
Diagram: InvictaHOG