In a new study, researchers found stress may lead to inflammation in the body, which links heart disease and depression.
The research was conducted by scientists at the University of Cambridge.
Inflammation is the body’s natural response to negative environmental factors. It is important for the body to fight against infection.
But lifestyle factors, such as stress, smoking, alcohol abuse, sedentary behavior, and obesity, could lead to harmful chronic inflammation.
Previous studies had shown that people with heart disease have a higher risk of depression and the opposite is also true.
However, whether the two diseases share common genetic risk factors or environmental risk factors is unknown.
In the current study, the team examined data of almost 370,000 middle-aged adults from the UK Biobank database.
They examined the link between family history of coronary heart disease and the risk of major depression.
The result showed that people with at least one parent died of heart disease was 20% more likely to experience depression.
After that, the researchers analyzed a genetic risk score for coronary heart disease to see how genes contribute to the increase in the risk of heart disease.
They found there was no strong link between the genetic contribution for heart disease and the risk of major depression.
Based on the findings, the team suggests that the link between heart disease and depression cannot be explained by a common genetic factor to the two diseases.
Instead, it implies that factors in a patient’s environment may not only increase the risk of heart disease but also increases the risk of depression.
In the next step, the team used a statistical technique called Mendelian randomization to examine 15 biomarkers linked to higher risk of coronary heart disease.
They found that triglycerides (a type of fat found in the blood) and two inflammation-related proteins were also risk factors for depression.
This finding suggests that the two diseases share common underlying biological mechanisms.
The researchers suggest the immune system may play an important role in both mental health and heart health.
Future work will try to understand the underlying mechanisms that drive both diseases.
One author of the study is Dr. Golam Khandaker, a Wellcome Trust Intermediate Clinical Fellow at the University of Cambridge.
The study is published in Molecular Psychiatry.
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