The human brain is filled with a near infinite number of mysteries, one of which is why certain neurological disorders, such as Alzheimer’s disease, are more common in women who have had children (European Journal of Neurology, doi.org/dwwz99). Now scientists may have stumbled upon their biggest clue to-date, which they discovered while analyzing the brains of mice.
In a recent study, scientists discovered that cells from a mother and fetus can cross the blood-brain barrier and enter the brain. And what’s more, fetal DNA can enter a mother’s brain and remain there for decades, according to autopsies of female brains. Lee Nelson of the Fred Hutchinson Cancer Research Center in Seattle performed autopsies on 59 brains of deceased women — 33 of whom had Alzheimer’s. As New Scientist writes, “They amplified the DNA that they found, creating many more copies, and looked for the presence of a male Y chromosome. They found it in 63 per cent of the brains. This male DNA showed up in many different brain regions and some of it had been there for a very long time: one brain that contained the male DNA was from a 94-year-old woman.”
So how is this possible? As Edward Scott of the Department of Molecular Genetics and Microbiology at the University of Florida in Gainesville predicts, it is almost certainly due to the presence of fetal cells in the mother’s body which are likely allowing her immune system to recognize her child’s cells, thus explaining why they wouldn’t be attacked. This discovery could open the door to mother-son transplants of various types that could take advantage of this DNA “bridge” and be relatively easy-breezy compared to transplants that do not have a DNA bridge.