Depression and inflammation (which can be a risk factor for heart disease) are known to be linked but scientists don't really know which comes first. Researchers from Indiana University in Indianapolis studied 263 people aged between 50 and 70 in an attempt to get to the bottom of this. They tested the participants for depression and measured their levels of an inflammatory protein called interleukin-6 at the start of the study and again six years later. They found that depressive symptoms were linked to higher levels of interleukin-6 six years later but high levels of interleukin-6 were not linked to depression later. The strength of the link between depression and a future risk of heart disease is as strong as those for smoking, high blood pressure and raised cholesterol.
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