Women are more resistant to Alzheimer's disease, according to a study in the journal Science.

Alzheimer's disease (AD) is the most common neurodegenerative disease that causes health threats around the world.
overall, there are more female patients than male patients.
, however, female patients are actually more resistant to AD: they live longer than men;
at the University of California, San Francisco (UCSF) recently revealed that this is because women have one more X chromosome than men, resulting in "double" genetic protection.
new study was published recently in Science Translational Medicine.
" findings challenge the long-standing dogm that women are more vulnerable to AD attacks.
Dubal, author of the study, said: "More women than men have AD because they live longer and the risk increases with age.
but women can also survive the disease longer.
To confirm the link between gender and AD pathogenesis, the team began with a meta-analysis that integrated data from 16 longitudinal studies that measured the duration of post-morbidity disease.
found that overall, male patients had a 62 percent higher risk of death than female patients.
similar trends have been replicated in model mice used to study AD's physios.
the brains of these mice produced toxic amyloid proteins to simulate human AD.
even though researchers removed the organs that produced sex hormones in mice when they were young, they found that male mice died earlier, suggesting that the difference was not caused by sex hormones.
, male mice showed faster cognitive decline in their learning and memory tests, even though their brains had similar levels of AD toxic proteins to those of females.
photo source: 123RF In terms of sex-determining sex chromosomes, female/female mice have two X chromosomes, male/male mice have one X chromosome and one Y chromosome.
, is the male's "disadvantage" due to the lack of an X chromosome or the possession of a Y chromosome? To distinguish between the two possibilities, the researchers introduced a group of mice with different sex chromosomes: in addition to the common XX and XY, there was an extra X chromosome male (XXY), and a female with an X chromosome removed (X0).
found that mice with two X chromosomes (including XX and XXY) lived longer and had better memory, regardless of whether they had Y chromosomes, when they were affected by AD toxic proteins.
this result means that the second X chromosome gives some protection.
next question is, how does the second X chromosome provide protection? Because in general, the second X-staining experience in female/female mice has a phenomenon called "inaction", in which genes are "silent" and do not produce proteins.
interestingly, a few genes on the X chromosome managed to escape this inhibition, allowing the protein it encoded to double its yield.
study, scientists noted one such gene, KDM6A.
past studies have found that KDM6A has a strong relationship with brain cognition and can cause intellectual disabilities if dysfunction occurs.
first examined the brains of mice and found that both copies of Kdm6a in female mice actively produced proteins, especially in the hema region.
this brain region, which we know is essential for learning and memory, is also the area that was the first to be affected in the early days of AD.
when researchers lowered Kdm6a levels in the female brain or increased Kdm6a in the male brain in mice in the AD model, the differences in cognitive decline they had previously shown were eliminated.
results, the Kdm6a gene produces more proteins that can better protect neurons from AD toxic proteins.
, to see if the association was also established in the human brain, scientists tested it in several public databases that study gene expression in the human brain.
From a sample of more than 500 people, they saw that KDM6A generally had higher levels of expression in the female brain, while AD patients had higher expressions of KDM6A in the damaged brain region than those without AD, and there was a clear correlation with less cognitive decline in older adults.
that this suggests that the protein produced by KDM6A may be some kind of compensation for resisting the development of AD.
because women have two X chromosomes, they get more protection from them. Professor
Dubal concludes that the study sheds light on the new role of sex chromosomes, and that "this protective mechanism on the X chromosome offers us a new possibility: by increasing KDM6A or other similar X factors, we can increase our resistance to AD and other neurodegenerative diseases."
" researchers are now further studying how to protect neurons with the KDM6A protein, hoping that the insights gained will benefit everyone, male and female.
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