Describing relationship, cause and effect

While there is plenty of evidence to suggest that stress in animals is related to cardiovascular problems, it is much more difficult to demonstrate the relationship in humans. This is because it is easy to expose groups of animals to different stressors and show that this has the effect of significantly increasing the incidence of cardiovascular problems. However, in humans, it is much more difficult to isolate stressors in a person's life, and as a result it is difficult to prove scientifically any causative link between stress and cardiovascular disease. Despite this, there’s a lot of circumstantial evidence to suggest a connection between stress and heart disease, and there are also some studies that have focused on heart attack patients which seem to show promising results for prevention of a second heart attack by using psychological therapies and stress-reduction techniques.