From the article:
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.
Of these common biomarkers, they found that triglycerides (a type of fat found in the blood) and the inflammation-related proteins IL-6 and CRP were also risk factors for depression.
Both IL-6 and CRP are inflammatory markers that are produced in response to damaging stimuli, such as infection, stress or smoking. Studies by Dr Khandaker and others have previously shown that people with elevated levels of IL-6 and CRP in the blood are more prone to develop depression, and that levels of these biomarkers are high in some patients during acute depressive episode. Elevated markers of inflammation are also seen in people with treatment resistant depression. This has raised the prospect that anti-inflammatory drugs might be used to treat some patients with depression. Dr Khandaker is currently involved in a clinical trial to test tocilizumab, an anti-inflammatory drug used for the treatment of rheumatoid arthritis that inhibits IL-6, to see if reducing inflammation leads to improvement in mood and cognitive function in patients with depression.
While the link between triglycerides and coronary heart disease is well documented, it is not clear why they, too, should contribute to depression. The link is unlikely to be related by obesity, for example, as this study has found no evidence for a causal link between body mass index (BMI) and depression.