Mother’s X chromosome could be responsible for brain ageing; study reveals

A new study recently discovered that the X chromosome the mother passes down may be responsible for accelerating brain ageing, which may result in an increased risk of Alzheimer's disease, among other diseases. This was discovered from a lab mice experiment, which further indicates that the influence of the maternal X chromosome on the brain could explain the cognitive decline experienced by women more than men. Women have longer lifespans but are at a higher risk of developing some brain disorders.


Humans have two sex chromosomes—females carry two X chromosomes (XX), while males have one X and one Y chromosome (XY). The X chromosome is known to carry significant genetic information, and any changes or mutations can have profound effects on health, particularly brain function. It happens to females where both the X chromosomes remain active. A random selection ensures that each cell possesses one non-actively performing X chromosome; in certain cases, such randomness causes varying expressions among X chromosomes, thereby affecting brain age and sensitivity toward cognitive loss.

The research work was designed upon female laboratory mice of various age groups for proving this idea. They silenced the paternal X chromosomes in some mice, leaving only the maternal X active. Such mice were to be compared with those that had both maternal and paternal X chromosomes. The result came as an affirmation that the young "Mom-X" mice, who only expressed the maternal X chromosome, had cognitive ability like their peers. However, when the mice were older, the mice with the maternal X alone showed a severe cognitive decline in the hippocampus, an area of the brain associated with learning and memory.
The study demonstrated that in these mice, the maternal X chromosome sped up the biological ageing process in the hippocampus, which might connect the maternal X with cognitive impairment.

This landmark discovery has enormous implications, where the question is how the part of the X chromosome passed from the mother plays its role in contributing to cognitive decline, especially in women, who are more predisposed to such diseases as Alzheimer's disease. According to lead author Dena Dubal, "These results suggest that women who inherit more activity of their mother's X chromosome may be at higher risk for cognitive impairments or Alzheimer's.". This finding may further aid in targeted strategy identification in the slowing down of brain ageing among both males and females.
While the study was conducted in mice, researchers believe that similar processes could occur in humans. Such findings, if confirmed in human studies, could open a window of understanding into the gender differences seen in cognitive decline and help to develop preventative measures or treatments for such conditions as Alzheimer's disease. The research opens up the possibility of exploring the influence of the X chromosome on ageing and brain health in ways not previously understood.
This study finally points out the role genetics play in brain health as complexities and how variations on the X chromosome might influence ageing and susceptibility to neurodegenerative diseases.
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