Social stress could lead to heart disease by causing the body to deposit more fat in the abdominal cavity and could also speed up harmful plaque build-up in blood vessels, according to new research.
In this study, female monkeys were fed a western-style diet containing fat and cholesterol. The monkeys were housed in groups so they would naturally establish a pecking order from dominant to subordinate.
Subordinate monkeys are often the target of aggression and aren't included in group grooming sessions as often as dominant monkeys.
Researchers found that these socially stressed subordinate monkeys developed more fat in the viscera, or abdominal cavity.
The researchers found that the stress of social subordination results in the release of stress hormones that promote the deposition of fat in the viscera.
Visceral fat, in turn, promotes coronary artery atherosclerosis, the build up of plaque in the blood vessels that leads to heart disease, the leading cause of death in the world today.
"Much of the excess fat in many people who are overweight is located in the abdomen, and that fat behaves differently than fat in other locations," said Carol A. Shively, principal study investigator, Wake Forest University School of Medicine (WFUSM).
"If there's too much, it can have far more harmful effects on health than fat located in other areas," said Shively.
Shively and colleagues found that women and female monkeys have a natural protection against heart disease -- women typically develop heart disease, on average, 10 years later than men do.
That protection seems to be lost when stress and visceral fat increase. Researchers found that the monkeys with high social stress and larger amounts of visceral fat also had ovaries that produced fewer protective hormones.
The study appeared in the current issue of Obesity.