With recent studies demonstrating that mental stress can lead to vasoconstriction, the constriction of blood vessels, Dr Michael Miller of the University of Maryland School of Medicine seeked to discover if the converse was true. Can positive emotions such as laughter improve vascular function?
Volunteers in the study were asked to watch a segment of a funny movie one day, and a sequence from a mental stress-inducing movie such as Saving Private Ryan on another. While they were watching, Dr Miller and his team measured the blood vessel diameter changes. Each volunteer served as their own control set-up.
The measurements revealed that when watching stressful scenarios, a volunteer’s blood vessel was more likely to undergo vasoconstriction, leading to a reduction of blood flow. Over the 300 measurements taken, there was a 30-50% difference in vessel diameter between the phases of laughter and mental stress. In fact, Dr Miller notes that the magnitude of change in the endothelium after laughter is consistent and similar to that observed after aerobic exercise or the administration of cholesterol-lowering drugs known as statins.
The endothelium is a thin layer of cells that line the interior surface of blood vessels. It is not only important for the regulation of blood flow, but also plays a vital role during the development of cardiovascular diseases. In diseases such as atherosclerosis, the hardening of the arteries, the endothelium is often the first to be breached.
Dr Miller believes the next step toward proving a concrete link between cardiovascular health and positive emotions lies in a randomized clinical trial. “What we really need is a randomized clinical trial to determine whether positive emotions reduce cardiovascular events above and beyond today’s standard of care therapies.”