Scientists said Thursday they may have uncovered a biological explanation for the long suspected link between stress and heart disease.
People with a highly
active amygdala — a region of the brain involved in stress processing —
also have a higher risk of heart disease and stroke, the researchers
revealed.
A hard-working amygdala
was also linked to increased bone marrow activity and inflammation of
the arteries, which may explain the higher heart disease and stroke
risk, the team said.
The data
suggested that stressed amygdala may send signals to the bone marrow to
produce extra white blood cells, which may in turn cause arteries to
narrow and become inflamed, causing cardiovascular problems.
The
potential link "raises the possibility that reducing stress could
produce benefits that extend beyond an improved sense of psychological
wellbeing," said lead author Ahmed Tawakol of the Massachusetts General
Hospital.
Published in The Lancet
medical journal, the study entailed PET and CT scans of the brain, bone
marrow and spleen activity, as well as artery inflammation, of 293
patients.
The group was surveyed
for 3.7 years on average, during which time 22 suffered "cardiovascular
events" — including heart attack, heart failure, stroke and narrowing of
arteries, said the study.
"Those
with higher amygdala activity had a greater risk of subsequent
cardiovascular disease and developed problems sooner than those with
lower activity," said the researchers.
In a sub-study, 13 patients with a history of post-traumatic stress disorder were tested separately.
"Those
who reported the highest levels of stress had the highest levels of
amygdala activity along with more signs of inflammation in their blood
and the walls of their arteries," the team found.
The
amygdala are almond-shaped neuron clusters deep in the brain thought to
regulate emotion, fear, anxiety, pleasure and stress.
Commenting
on the study, Ilze Bot of Leiden University in the Netherlands said the
data identified chronic stress "as a true risk factor" for
cardiovascular diseases.
Given the
increasing number of people suffering from job or social stress,
doctors may have to include it when they assess an individual's risk for
cardiovascular disease, she said.
A
2014 study said chronic stress may trigger an overproduction of white
blood cells which clump together on artery walls, restricting blood flow
and encouraging clot-formation, to raise heart attack and stroke risk.
