Will Ferrell is Good For Your Arteries.

Well, assuming you find Will to be funny then watching his movies just might improve the functional responses of your arteries. You might have heard "laughter is the best medicine" or maybe even that laughing is good for your heart. But is there any truth to this? The journal Heart (formerly the British Heart Journal) published a scientific letter titled "Impact of cinematic viewing on endothelial function" in 2006 that just might have the answer (link to abstract). Heart 2006;92:261–262

These authors studied the blood flow responses in the arteries of the arm in subjects before and after they watched movies. They compared the vascular responses of individuals that watched movies evoking mental stress (e.g., Saving Private Ryan) versus individuals watching movies evoking laughter (e.g., There's Something About Mary).

They found movies that made you laugh improved endothelial-dependent blood vessel dilation (see the figure below)... this is a fancy way of saying that the arteries and arterioles dilated more in response to a stimulus and thus improved blood flow. The laughter group had improved arterial vasoldilation compared to baseline while the mental stress group actually had impaired vasodilation compared to baseline. They tested this using reactive hyperemia which A&P students remember from lab. Reactive hyperemia is a transient increase in blood flow to an organ or tissues after a period of ischemia or arterial occlusion. Basically, the authors occluded blood flow to the arm for five minutes (ouch) and then released the occlusion. They used ultrasound imaging to capture the diameter changes in the brachial artery during the experiments to assess the functional responses during hyperemia. In class, we merely looked at the redness in the skin to assess the extent of hyperemia (see our class images). In the movie experiments, during hyperemia, brachial arteries dilated to a greater extent in the arms of laughter viewers. By the way, the reason it is called "endothelial-dependent" is because the endothelial cells are important in generating the signals that contribute to the blood flow changes. The mechanisms explaining the findings of this study are unknown but the authors did speculate that nitric oxide (NO) signaling could be involved. You might remember that NO produced by cells, like endothelial cells, can cause smooth muscle relaxation and thus improve blood flow.

Conclusion: go see funny movies and not stressful or scary ones! Superbad, not super scary... after all, it is good for the function of your arteries.

Heart 2006;92:261–262

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