For the fatalists among us, wrinkles are the prophets of doom – a sure sign that old age has officially arrived.
But while forehead wrinkles are common, even among young people, those with deeper and more numerous brow lines may have something far more ominous to worry about than simple, inevitable ageing.
A new study has found that brow wrinkles may in fact be an early warning of heart disease, and scientists still aren't sure why.
"You can't see or feel risk factors like high cholesterol or hypertension," says study author Yolande Esquirol, a physician and biomedical researcher at the Centre Hospitalier Universitaire de Toulouse in France.
"We explored forehead wrinkles as a marker because it's so simple and visual. Just looking at a person's face could sound an alarm, then we could give advice to lower risk".
It sounds absurd, but if the connection is verified, forehead wrinkles could join a whole bunch of other strange and unusual assessments for heart disease, including creased earlobes, loose teeth, male pattern baldness, clubbed fingernails, cataracts in the eye, and swelling in the hands, ankles, or feet.
To be clear, not all wrinkles convey this risk. Past research, for example, has found that crow's feet - the tiny lines that radiate from the corners of our eyes - are not linked to heart disease, but rather, are a simple consequence of ageing and movement.
Nor do these physical signs of heart disease replace deeper and more thorough medical testing. They are simply an easy and low-cost way for doctors to identify which of their patients are at a higher-risk of developing heart disease later on in life.
"Of course, if you have a person with a potential cardiovascular risk, you have to check classical risk factors like blood pressure as well as lipid and blood glucose levels, but you could already share some recommendations on lifestyle factors," Esquirol explains.
The study examined horizontal forehead wrinkles in a group of 3,200 working adults - all of whom were deemed to be in good health, and were aged 32, 42, 52, and 62 at the beginning of the study.
After being given a score out of three for the number and depth of their brow wrinkles, the researchers followed these participants for two decades.
Out of the 233 people who died for various reasons during the course of the study, 15.2 percent had scored a two or a three for their brow wrinkles, 6.6 percent had scored a one, and 2.1 percent had scored a perfect zero (meaning they had no forehead wrinkles).
What the data showed was that with every increase in wrinkle score, the risk of dying from cardiovascular disease increased. While there was a slightly higher risk from zero to one, those who had wrinkle scores of two and three had almost 10 times the risk of dying from heart disease than those who scored zero.
And this was true even after the researchers took into account other factors that predict heart disease like age, gender, job strain, education, smoking status, blood pressure, heart rate, diabetes, and lipid levels.
"The higher your wrinkle score, the more your cardiovascular mortality risk increases," concludes Esquirol.
The reason or reasons behind this connection are still not yet understood. But the authors think that forehead wrinkles may be a marker of atherosclerosis – a major contributor to heart attacks that occurs when plaque builds up in our arteries.
As the arteries become thick and stiff, blood flow that carries nutrients and oxygen to important organs and tissues can be restricted.
Just like atherosclerosis, wrinkles are also linked to changes in plaque collagen and reductions in oxygen availability.
Because the blood vessels in the forehead are so minute, they are especially vulnerable. The researchers propose that even small changes in plaque build-up could alter their function and appearance.
"This is the first time a link has been established between cardiovascular risk and forehead wrinkles, so the findings do need to be confirmed in future studies," cautions Esquirol, "but the practice could be used now in physicians' offices and clinics."
"It doesn't cost anything and there is no risk".
The research has been published in Archives of Cardiovascular Diseases Supplements.