Heart disease and stroke killed more than 787,000 people in
2010 -- about one in three Americans. A new study suggests a "stress gene"
may be to blame for some of these deaths.
While obesity, high blood pressure, smoking, physical
inactivity and eating a high-sodium diet devoid of fruits and vegetables all
can raise risk for cardiovascular problems, the study authors say they've found
a biological explanation for why some people are predisposed to develop heart
disease or die early from a stroke or heart attack.
"The exciting part to me this is that this genetic
trait occurs in a significant proportion of people with heart disease," Dr.
Beverly Brummett, an associate professor of psychiatry and behavioral sciences
at Duke University School of Medicine in Durham, N.C., said in a statement.
The study builds on work scientists previously did to identify a
genetic variant called a single
nucleotide polymorphism, or SNP, in a DNA chain that makes a receptor
neurotransmitter serotonin. Serotonin is a chemical messenger in the
brain that is tied to emotion regulation. Essentially,
an SNP is when one letter in a DNA sequence is swapped with another
letter, which leads to a change in function. I this case, the function
of the gene is changed to cause a hyperactive
reaction to stress.
The researchers point out that a study last year found men
with these gene variants had twice as much cortisol, a hormone related to
stress, in their blood while under stress compared to men without the
"It has been shown that high cortisol levels are
predictive of increased heart disease risk. So we wanted to examine this more
closely," said Brummett.
They conducted a genetic analysis of more than 6,100
people who underwent cardiac catheterization procedures, two-thirds of whom
were male. In that procedure, a long, flexible tube is threaded through a blood
vessel in the arm so doctors can perform tests or treatments that directly target the bloodstream.
They found the overactive stress gene in 13 percent of the
patients. After tracking them for six years, the researchers discovered the
genetic trait raised risk for heart attack and early death by 40 percent. This was the case even after ruling
out other factors like age, obesity, smoking history and severity of their
The study didn't look specifically at what is going on in
the body to cause this increased risk, but the researchers have a theory that
rising cortisol levels cause elevations in an ezyme called "MMP9." This enzyme
breaks down plaques in blood vessels, making them more likely to form cloths
that could cause a blockage that leads to a heart attak.
"If we can replicate this and build on it, we may be
able to find ways to reduce the cortisol reaction to stress -- either through
behavior modification or drug therapies -- and reduce deaths from heart attack,"
The study was published Dec. 18 in PLoS One.
Previous research has linked stress and rising cortisol levels to Alzheimer's disease risk