Men like to think of themselves as the stronger sex, yet they are regularly outlived by the women in their lives.
Now scientists may have worked out why.
They say that the Y chromosome, or more specifically, the loss of it, may be to blame for men’s shorter lifespans.
Only found in men, the Y chromosome contains the DNA that makes males male and is present in almost every cell in the body.
But, in some men, it starts to disappear from some of their blood cells as they get older.
Previous research has shown these men are more likely to die young and to suffer from a range of cancers.
Now, scientists have also linked loss of the Y chromosome to Alzheimer’s disease.
And they say that while the missing DNA has no effect on a man’s manliness, it may help explain why males, as a whole, tend to die younger.
The researchers, from Uppsala University in Sweden, came up with the theory after studying more than 3,200 men aged between 37 and 96.
Tests showed the Y chromosome to be missing from white blood cells in roughly one in five men.
And the older they were, the more common it was.
Health records showed Alzheimer’s disease to be almost three times as common in men affected by the phenomenon.
And apparently healthy men were almost seven times as likely to go on to develop the memory-robbing condition if they were missing Y chromosomes.
The white blood cells involved form part of the immune system, and it is thought that without their Y chromosome, they struggle to work properly.
This could leave the body vulnerable to a host of ills, from dementia to cancer, the European Society of Human Genetics annual conference in Barcelona heard yesterday.
Researcher Lars Forsberg said: ‘The blood cells we studied are involved in the immune system, and the fact that loss of the Y chromosome in them is associated with disease in other tissues is striking.
‘We therefore hypothesise that the loss of Y chromosome in blood cells leads them to lose part of their immune function.’
He said that since women do not carry a Y chromosome, the phenomenon may help explain why they tend to have longer lives.
Excitingly, a simple blood test could help spot men with defective white blood cells.
These males could then be closely monitored for cancer or memory loss and treated early, when there is the best chance of success.
Professor Forsberg said: ‘In short, the widespread use of loss of Y chromosome testing could radically decrease male mortality rates, and even perhaps eliminate the difference in life expectancy between the sexes.’
According to the Office for National Statistics, a 65-year-old man can expect to live for another 18.8 year, until he is almost 84.
A woman of the same age will have another 22.1 years, on average, meaning she will see her 86th birthday.
The reasons normally given for the longevity gap range from men working themselves into an early grave, to differences in hormones.
The simple fact that men tend to be bigger – and so have more cells that could become damaged and diseased – could also be important.
However, the gender gap in life expectancy is narrowing, perhaps the stressful lives of career women and the toll of drinking and smoking on their health.
British experts said learning more about the link between the Y chromosome and dementia could lead to much-needed new treatments.
Dr Simon Ridley, of charity Alzheimer’s Research UK, the UK’s leading dementia research charity, said:
‘This interesting study points to a potential new avenue to explore for researchers investigating the development of Alzheimer’s disease.
‘In Alzheimer’s, the first changes in the brain occur many years before symptoms begin to show, and we can’t be certain from this study whether loss of Y chromosome may be part of the chain of events driving the disease or a result of the disease.
‘Further research may allow us to uncover more information about the molecular processes underpinning the disease, an important step in the search for treatments.
‘It’s important to note that not all men with loss of Y chromosome in this study developed Alzheimer’s disease.
‘Alzheimer’s disease is the most common cause of dementia, and with no treatments currently able to alter its course, research to understand the disease is vital.
‘If we are to find new treatments and improve the way the disease is diagnosed, we must continue to invest in research.’
Source: Daily Mail