How Does Male DNA Get Into a Woman's Brain?

By Sophie Bushwick | September 27, 2012 1:19 pm

brain

Some women always have men on the brain. And some women literally have men in their brains. A new study in PloS ONE found that quite a few female brains contain male DNA. This genetic material presumably passes into a mother while she is pregnant with a male fetus. Although we already knew that fetal cells can enter a mother’s body, until now, it was unknown whether the cells could pass into the brain as well, because the blood brain barrier normally blocks large molecules and foreign substances from entering the brain.

To explore the possibility of brain microchimerism—the presence of genetically distinct cells in a host’s body—researchers examined autopsy specimens from 59 deceased female subjects, who either had no neurological disease or had suffered from Alzheimer’s. The scientists found that 63 percent of the brains contained male cells distributed throughout the organ, and that this microchimerism did not fade away over time: the brain of one 94-year-old woman still contained male cells. And interestingly, the brains of subjects with Alzheimer’s disease were less likely to contain male DNA, and when they did, they generally had less of it than the healthy brains did.

These results suggest that during pregnancy, the blood brain barrier becomes more permeable and allows fetal cells to enter the mother’s brain. Male fetal cells put male DNA into female brains, and female fetal cells would presumably enter the mother’s brain as well—this particular analysis of the samples, however, was unable to reveal their presence. But the researchers only had limited information about their subjects’ history of pregnancy. Only 9 of all the subjects were known to have sons, and at least 2 had no male children. The researchers suggest that male DNA in the brain may also have come from a miscarried or aborted male fetus. Or the male cells may not have entered the body during pregnancy after all. Some women may have acquired the foreign genetic material from a twin or older sibling who left DNA behind in the womb. Even a blood transfusion could have transferred male cells to the blood, and then to the brain.

While this study only looked at about 60 brains, which is a fairly small sample size, the definite presence of male DNA shows that fetal cells can sneak past the mother’s blood brain barrier. But to clarify that these are indeed fetal cells, rather than coming from another source, the researchers may want to autopsy a few more samples—samples with known pregnancy histories. Then we can see if the fetal cells have any affect on the risk of Alzheimer’s disease.

Image courtesy of John A. Beal / Wikimedia Commons

CATEGORIZED UNDER: Health & Medicine, Mind & Brain
  • Magoonski

    So could we just skip the whole pregnancy thing and just inject fetal cells into our brains as a prevention method?

  • Pierrette

    My Mother had two sons and has Alzheimer’s. She also was very intelligent and had an enormous vocabulary due to playing crossword puzzles daily. She now has trouble spelling simple words. I hope that a cure is found soon.

  • Chris

    Mmmmm, baby brains. Sweet tasty baby brains.

  • Amos Zeeberg (Discover Web Editor)

    @Magoonski: Getting IRB (institutional review board) approval for that experiment might be hard.

  • Susan

    WOW! I have two brothers and I’ve given birth to 7 boys! I’m sure I have a lot of cells floating around!

  • Mark Truman

    What about through semen?

  • Grumiester

    So, this means that mothers really don’t have eyes in the back of their heads. We are already in their heads. So, that’s why they know what we are going to do, before we do it. That explains a lot about my childhood. I couldn’t get away with nothing, no matter how hard I tried.

  • Pippa

    #5 – yes Grumiester – I used to call it “Mummy Magic” Now I know it was cerebral invasion. No wonder children are always on the minds of their mothers!
    That being said, I like the idea of having some aspect of my son still there although we are very appropriately apart now that he is moving towards independence and adulthood.

  • dsc

    Friggin weird. AS IF pregnancy wasn’t bizarre enough already without that.

  • http://2012.ak4mc.us/ McGehee

    I never suspected, when I was a kid, that I was living rent-free in my mother’s head…

  • Dennis

    I have often wondered whether there is more than just the act of sex shared between both partners. One looks at long term marriages, where the individuals also had a good sex life, there seems to be the ability to know what each of them are thinking and answers to questions before they are asked. If it only takes billionths of a part to have an affect is there not a possibility that we are both haring more than we might have thought shared previously?
    Just a question?

  • teapartydoc

    Professor Henry Higgins call your office. Women can be more like men.

  • Jane

    I wonder if women with multiple partners — multiple babies from several different fathers, for example, would have a greater risk of diseases.

    It’s interesting how things that are Biblical are proved true in science so often: “the two shall become one flesh,” and the admonition about being monogamous.

  • Jek

    Having lost my son 4 years ago, it’s rather nice to think that part of him is still with me in a very real sense. He used to say I was psychic when it came to knowing what he was thinking. What a marvelously mystery thing life is.

  • http://www.pacrimjim.com PacRim Jim

    Given that we live in a era of serial monogamy, several males get into her brain.

  • http://made-in-afrika.com/aloes eurica

    I read that not all women tested had sons. Is that not enough to scrap the pregnancy option? Anything to cure or prevent Alzheimer’s is so important.

  • Rosemary Lyndall Wemm

    Are these fetal brain cells functioning as brain cells in the recipients?

  • Joyce Miller

    So if the researchers are not sure that the cels are from fetal male cells, why not check the brains of men to see if they have female DNA?

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