A team at the University of London have just published a report of their study linking stress to atheroschlerosis (narrowing of the arteries), which is a major factor in heart attacks. Hamer et al. (2010) worked with 514 healthy men and women (mean age 62.9 years). The participants were given various tasks to increase their stress levels (such as the Stroop task). Cortisol levels in the saliva were measured before and after the stress tasks (cortisol is a hormone produced when we are stressed). Coronary artery calcification (thickening) was also assessed. The study found that only 40% of the participants had raised cortisol levels after the task but of this group there were significantly more people with thickened arteries. These results support the idea that hypothalamic pituitary adrenal activity (which produces cortisol) is a risk factor for CHD.