Giving a whole new meaning to “pregnancy brain,” a new study shows that male DNA-likely left over from pregnancy with a male fetus-can persist in a woman’s brain throughout her life. Although the biological impact of this foreign DNA is unclear, the study also found that women with more male DNA in their brains were less likely to have suffered from Alzheimer’s disease-hinting that the male DNA could help protect the mothers from the disease, the researchers say.
During mammalian pregnancy, the mother and fetus exchange DNA and cells. Previous work has shown that fetal cells can linger in the mother’s blood and bone for decades, a condition researchers call fetal microchimerism. The lingering of the fetal DNA, research suggests, may be a mixed blessing for a mom: The cells may benefit the mother’s health-by promoting tissue repair and improving the immune system-but may also cause adverse effects, such as autoimmune reactions.
One question is how leftover fetal cells affect the brain. Researchers have shown that fetal microchimerism occurs in mouse brains, but they had not shown this in humans. So a team led by autoimmunity researcher and rheumatologist J. Lee Nelson of the Fred Hutchinson Cancer Research Center in Seattle, Washington, took samples from autopsied brains of 59 women who died between the ages of 32 and 101. By testing for a gene specific to the Y chromosome, they found evidence of male DNA in the brains of 63% of the women. (The researchers did not have the history of the women’s pregnancies.) The male DNA was scattered across multiple brain regions, the team reports online Wednesday in PLoS ONE.
Because some studies have suggested that the risk of Alzheimer’s disease (AD) increases with an increasing number of pregnancies, the team also examined the brains for signs of the disease, allowing them to determine whether AD correlated with the observed microchimerism. Of the 59 women, 33 had AD-but contrary to the team’s expectation, the women with AD had significantly less male DNA in their brains than did the 26 women who did not have AD.
Whether that correlation means that fetal male DNA helps protect women against AD is unclear, however. “To me, this suggests that the presence of fetal cells in the female brain prevents disease,” says cardiologist Hina Chaudhry of Mount Sinai School of Medicine in New York City.
In a study published online in Circulation Research late last year, Chaudhry and colleagues found that fetal cells in mice migrated to the mother’s heart, differentiated into functioning cardiac cells, and accelerated repair to damaged heart tissue. So, Chaudhry says, a similar thing could be happening when fetal cells migrate to the brain. “I would bet these cells are getting into the maternal brain and are able to differentiate into neurons.”
A 2010 study in Stem Cells and Development showed that fetal cells can migrate to the brain of a mother mouse and mature into neurons, Nelson says. But, she adds, it remains unclear if something similar is happening in humans-and it’s also difficult to reach any firm conclusions about a potential link between microchimerism and AD. Part of the problem is that her team had little information about the pregnancy histories of the women in their study. “We have to say we really don’t know,” she says. “I hope that kind of work can be done in the future, but it’s very difficult to do with human samples.”
my grandmother gave bith to six son and she had Alzheimer’s disease, personally i think they need more fact before they even imply that this stuff might be true
I laughed when I read this article, my mother had seven sons and she too has Alzheimer’s disease. I personally think having seven sons is what gave her Alzheimer.
They also stated “some studies have suggested that the risk of Alzheimer’s disease (AD) increases with an increasing number of pregnancies”
Most of the women I’ve met where my mother is being cared for had 1-3 children. There are several who never had any.
You must be glad she had at least one son..
I’m one of her precious daughters.
All medical research starts with a hypothesis, or idea. No one has declared the above research as factual. And just because there’s a relationship, which can increases a risk, doesn’t mean that having A always causes B. It’s been proven that life-long heavy drinking and smoking increased the risk of early death, but we have all heard about the 98-year-old who did so their entire life and were healthy as a horse.
I hypothesize that if a woman has not had any children, male or female, but is on a humanised monoclonal antibody based on a murine model, then she is protected against Alzheimers disease.
My second hypothesis is that if a woman is exposed to male mouse dander, droppings or urine she inhales some murine DNA and is protected against Alzheimers disease.
It’s always those silly mice that come out on top!
Can anyone send me a few million in grant money to test these ideas??
;)
in a nutshell, you are asking for money to have women sniff mouse turds?
oooookay.
I guess you missed the sarcasm, huh?
The researchers did not have the history of the womens’ pregnancies.
I don’t have to know if they sniffed, ingested, inhaled or otherwise were exposed to mice. All I have to do is test them to see if there are any murine genes in their genetic makeup. If even one is found I can theorize that the murine gene protects them from Alzheimers if they don’t have it. I already know that murine genes enable certain drugs to modify the immune system. Gotta be worth a few million to test the hypothesis!
I’m sure a whole shirtload of money funded the study cited in the article. I’m in the wrong business!
The check is in the mail.
…”(The researchers did not have the history of the women’s pregnancies.) “…
I don’t think they needed to, since they would not normally find male DNA in the brain of women who had not been pregnant with males. The correlation was between a gene specific to the male chromosome and it’s relationship to Alzheimer’s diseases.
So, I guess this would mean those men who think their wives are different after having children may be on to something? Wouldn’t that also mean that if they no longer want to be with their wives for such reasons that they can’t live with themselves? Then how could they live with the kids, who are also a piece of them?
On the other hand, without knowing the women’s pregnancy history this could be thrown away. Some people are known to have various genes, and sometimes a Y gene, and for those genes tested that are supposedly Y chromosome specific, are they sure they are completely Y chromosome dependent, or is this another spot where the X chromosome can take over? The X chromosome is more complete than the Y chromosome…… DNA is complex.
I think that having sons does affect a woman’s brain. Particularly once they hit adolescence and start driving her crazy.
finding this interesting. I have a 7 year old son and of my two kids, he is the most challanging for sure and really knows how to try his moms patience.. Love him dearly but what will it be when he is a teen ager.