A genetic trait that has been linked to higher stress levels in the past may also be associated with an elevated risk of heart attack in patients already struggling with cardiovascular diseases.
The study results gives researchers insight into why some people are predisposed to cardiovascular disease and heart-related death; medical researchers suggests "behavior modification and drug therapies" could help affected individuals lower their risk, a Duke University Medical Center news release reported.
"We've heard a lot about personalized medicine in cancer, but in cardiovascular disease we are not nearly as far along in finding the genetic variants that identify people at higher risk," senior author Redford B. Williams Jr., M.D. director of the Behavioral Medicine Research Center at Duke University School of Medicine, said. "Here we have a paradigm for the move toward personalized medicine in cardiovascular disease."
The researchers looked at variations in DNA sequences called single nucleotide polymorphisms (SNP), "where one letter in the genetic code is swapped for another to change the gene's function," the news release reported. The researchers pinpointed an SNP that causes a hyperactive stress reaction in people who possess it.
The team found those with the SNP and a cardiovascular disease also had a 38 percent increased risk of heart attack or cardiovascular death over those that did not possess the genetic trait.
The researchers reported that men who had the SNP had twice as much cortisol in their blood when exposed to stress as those who did not. Cortisol is known as the "stress hormone," and is released by the adrenalin gland to help the body deal with negative emotions.
"It is known that cortisol has effects on the body's metabolism, on inflammation and various other biological functions, that could play a role in increasing the risk of cardiovascular disease," lead author Beverly H. Brummett, Ph.D., associate professor of Psychiatry and Behavioral Sciences at Duke, said. "It has been shown that high cortisol levels are predictive of increased heart disease risk. So we wanted to examine this more closely."
The researchers performed genetic analyses on 6,100 white participants; two-thirds of the subjects were male and about 13 percent of the entire group had the genetic variation in question.
The team found the trait was linked to a higher risk of heart trouble even when other lifestyle factors were taken into account.
The researchers believe the increased risk could be associated with a compound in the blood that rises in unison with the cortisol. The compound, an enzyme called MMP9, has been known to soften plaque on blood vessels; this leads to a higher risk of a clot or rupture.
"We plan to study this further," Williams said. "But what this work suggests already is that we have a found genetic variant that can be easily identified, so we can begin to develop and test early interventions for those heart patients who are at high risk of dying or having a heart attack."
The exciting part to me this is that this genetic trait occurs in a significant proportion of people with heart disease," Brummett said. "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."
