A hidden genetic mutation could predict a man's likelihood of developing dementia.
That's according to an Australian study led by Monash and Curtin Universities, which analyzed the medical data of thousands of Australians and Americans.
Men who had a certain variant in the haemochromatosis (HFE) gene - which regulates iron levels in the body - were found to be at a higher risk of dementia, the researchers found.
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Previously healthy men over age 70 who have two copies of the variant, which is known as H63D, are at least twice - or up to four times - as likely to develop dementia.
Having just one copy did not appear to elevate the risk.
One in 36 men carry two copies of the mutation; one in three have just a single copy.
"It is only men who have two copies of the variant that are at risk," study co-author Professor John Olynyk from the Curtin Medical School told Fox News Digital. "Women are not affected by the abnormality - we do not know why that is at the current point in time."
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The study, which was published in the journal Neurology, used data from the ASPirin in Reducing Events in the Elderly (ASPREE) trial, which gathered health and aging data for 19,114 healthy older adults.
Those who have the genetic variant can't change it, but it's possible that the "brain pathways" it affects could be treated, Olynyk noted.
"The HFE gene is routinely tested for in most Western countries … when assessing people for haemochromatosis, a disorder that causes the body to absorb too much iron," the doctor said. "Our findings suggest that perhaps this testing could be offered to men more broadly."
Despite the fact that the HFE gene is responsible for controlling iron levels, the team found no direct link between iron and dementia risk.
"This points to other mechanisms at play, possibly involving the increased risk of brain injury from inflammation and cell damage in the body," Olynyk added.
More research is needed to determine why the heightened risk wasn't seen in women.
"Understanding why men with the double H63D variant are at higher risk could pave the way for more personalized approaches to prevention and treatment," added co-author Professor Paul Lacaze from Monash University in a press release.
The main limitation of the study, according to Olynyk, was that the study population was largely composed of Australians.
"Whether other populations exhibit the same effects is unclear," he told Fox News Digital. "Our work should be repeated in different countries to assess this."
"Further research will be undertaken to try and determine the likely mechanism by which this anomaly causes dementia and what more we can do to reduce the impact of it."
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Beyond this specific mutation, many other genetic and environmental factors can contribute to dementia risk, Olynyk noted.
"While genetic risk factors cannot be changed, the mechanisms by which these genetic abnormalities and environmental factors cause disease may well be modifiable to some extent, through adopting a healthy lifestyle and being proactive about maintaining an overall good state of health," he said.
To reduce risk, the researchers recommend adopting a healthy lifestyle that includes exercising regularly, eating a nutritious diet, minimizing alcohol intake, remaining mentally active, and seeing a doctor to address any medical problem known to increase the likelihood of dementia.
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The University of Melbourne, The Royal Children's Hospital, Murdoch Children's Research Institute and Fiona Stanley Hospital also contributed to the study.
