March 19, 2019 - 16:39 AMT
PanARMENIAN.Net - People with heart disease are more likely to suffer from depression, and the opposite is also true. Now, scientists at the University of Cambridge believe they have identified a link between these two conditions: inflammation—the body's response to negative environmental factors, such as stress, Medical Xpress reports.
While inflammation is a natural response necessary to fight off infection, chronic inflammation—which may result from psychological stress as well as lifestyle factors such as smoking, excessive alcohol intake, physical inactivity and obesity—is harmful.
The link between heart disease and depression is well documented. People who have a heart attack are at a significantly higher risk of experiencing depression. Yet scientists have been unable to determine whether this is due to the two conditions sharing common genetic factors or whether shared environmental factors provide the link.
"It is possible that heart disease and depression share common underlying biological mechanisms, which manifest as two different conditions in two different organs—the cardiovascular system and the brain," says Dr. Golam Khandaker, a Wellcome Trust Intermediate Clinical Fellow at the University of Cambridge. "Our work suggests that inflammation could be a shared mechanism for these conditions."
In a study published today in the journal Molecular Psychiatry, Dr. Khandaker and colleague Dr. Stephen Burgess led a team of researchers from Cambridge who examined this link by studying data relating to almost 370,000 middle-aged participants of UK Biobank.
First, the team looked at whether family history of coronary heart disease was associated with risk of major depression. They found that people who reported at least one parent having died of heart disease were 20% more likely to develop depression at some point in their life.
Next, the researchers calculated a genetic risk score for coronary heart disease—a measure of the contribution made by the various genes known to increase the risk of heart disease. Heart disease is a so-called 'polygenic' disease—in other words, it is caused not by a single genetic variant, but rather by a large number of genes, each increasing an individual's chances of developing heart disease by a small amount. Unlike for family history, however, the researchers found no strong association between the genetic predisposition for heart disease and the likelihood of experiencing depression.
Together, these results suggest that the link between heart disease and depression cannot be explained by a common genetic predisposition to the two diseases. Instead, it implies that something about an individual's environment—such as the risk factors they are exposed to—not only increases their risk of heart disease, but at the same time increases their risk of depression.