Scientists have unearthed a possible reason why men tend to die at younger ages than women: Those who lose Y chromosomes from their blood cells as they age may be more vulnerable to heart tissue scarring and heart failure.
The research is the latest to look at the phenomenon of “mosaic loss of Y” — where the Y chromosome disappears from a portion of a man’s blood cells.
Researchers do not know why it happens, but it is associated with aging: It’s detectable in an estimated 40% of 70-year-old men, and more than half of those who live into their 90s.
At one time, researchers thought that losing Y — a small, stumpy chromosome — was just a part of normal aging.
But in recent years, studies have linked Y loss to increased risks of conditions like Alzheimer’s, heart disease and certain cancers, as well as a shortened life span.
Those studies, however, could not show whether the chromosome loss directly contributes to diseases, or is merely a sign that other body processes are going awry.
“The question is, is loss of Y simply a marker of aging, like graying hair?” said study co-author Kenneth Walsh.
His team’s findings suggest the answer is no: In lab mice, loss of Y in blood cells made heart tissue prone to scarring and led to an earlier death.
It’s evidence that the chromosome loss is a direct player, not just a bystander, according to Walsh, who directs the Hematovascular Biology Center at the University of Virginia School of Medicine.
Most people know the Y chromosome as a sex chromosome: Women have two X chromosomes, while men have an X and a Y.
Researchers used to think the Y chromosome did little more than determine male sex characteristics. But studies in recent years have found that the Y chromosome contains more genes than previously thought — whose jobs are not fully known.
In parallel with that work, research has linked a loss of Y to various disease risks.
To get at the why, Walsh and his team conducted studies in both humans and lab mice.
For the former, they used a large research database with medical and genetic information on about 500,000 British adults. They found that men who entered that study with a significant loss of Y — in over 40% of their blood cells — fared worse over the ensuing years.
They were 41% more likely to die of any cause over the next seven years, versus men without loss of Y. Specifically, they were about two to three times more likely to die of heart failure or heart disease related to longstanding high blood pressure.
To directly test the effects of Y loss, Walsh’s team used “gene-editing” technology to create lab mice that lacked the chromosome in many of their blood cells.
They found that in aging male mice, that Y loss sped up age-related changes in heart structure and function, and made the animals more vulnerable to scarring in the heart, as well as the lungs and kidneys. In one experiment, the chromosome loss made existing heart failure worse.
Walsh said that Y chromosome loss appeared to alter the function of immune cells that operate in the heart, leading to tissue scarring.
Top Five Reasons Why Men Die Before Women
The average life expectancy for an Australian man is 79.2 years, according to the Australian Bureau of Statistics (ABS). For an Australian woman, it’s 83.7 years. But to say that’s simply part of nature’s plan is only half-true; there are many factors to consider when assessing why women can expect to live longer lives. These factors can have significant impact on life insurance policies.
1. Nature assists women
Female hormones do more then simply alter moods – they possess properties that can help to protect some women who haven’t yet reached menopause from heart disease, which is the leading cause of death in Australia.
2. Men put themselves at higher risk…
High-risk activities including physically dangerous jobs such as labouring, high impact sports such as rugby and dangerous driving, place men at a much higher risk of injury and death at an earlier age than women. According to the New South Wales Roads and Traffic Authority, 469 male drivers were involved in fatal car crashes in 2009 across NSW compared to 118 women.
…and can’t beat old habits
We all know smoking and excessive drinking are detrimental to our longer term health, yet men persist with these harmful habits. On average, they’re bigger smokers and drinkers than their female counterparts across almost all age groups. Cancer Council Victoria’s study Tobacco in Australia: Facts and Issues shows that 21 per cent of males in Australia smoke, compared with 18 per cent of females. Similarly, the ABS reports that 15 per cent of adult males drink at dangerously high levels compared to 12 per cent of the adult female population.
3. Men tend to forget to watch their weight
Men are more likely to think they are within a safe weight range even if they are not. Twenty-two per cent of obese men believe they meet healthy weight guidelines compared to 12 per cent of obese women. A whopping 67 per cent of Australian men (aged 25 and over) are overweight, while 52 per cent of women in that age bracket are also tipping the scales at unhealthy levels.
4. Men are more susceptible to cancer
According to the Cancer Council, half of all Australian men will be diagnosed with cancer before the age of 85. This daunting forecast is not quite as grim for the female population of Australia, with a third of women to be diagnosed with cancer before the age of 85.
Amid this doom and gloom in mind, one thought can provide comfort to the male population: the shorter life expectancy of males is due in part to lifestyle factors, and you’re never too old to change your ways and improve your chances of a longer and brighter future.
Other possible causes have been put forward, including differences at chromosomal or genetic level. The Y chromosome tends to develop more mutations than the X chromosome, and abnormalities in X chromosomes in males are not masked by a second ‘good’ version, as they may be in females. Developmental disorders are more common in boys.
Boys and men in every age group die more often, particularly in their fifties and sixties, when the gap widens even more before narrowing again.
Men are also more likely to be homeless, or in custody.
What can we do to improve life expectancy?
Live as healthily as we possibly can by:
• not smoking
• limiting alcohol consumption
• eating a healthy balanced diet
• drinking plenty of water
• getting enough sleep
• maintaining a healthy body weight
• getting regular exercise
• reducing stress
• reducing exposure to toxins and radiation
• seeking medical advice when you have physical or mental symptoms
• having regular medical check-ups, and completing recommended screening tests, such as breast and bowel cancer screening.