Dov Michaeli
First posted 8/29/11 on the Doctor Weighs In
I came across an item in today’s MedPage (Aug29, 2011) reporting on two papers presented at the European Society of Cardiology meeting in Paris. The first, by Dr. Bonaguidi of the Institute of Clinical Physiology in Pisa, Italy, assessed how anger-prone behavior affected prognosis among survivors of an acute myocardial infarction.
In addition to the psychological evaluations, his group looked at clinical data such as traditional risk factors and left ventricular wall motion score index as measured by 2-D echocardiography.
He recruited 228 patients, 200 of whom were men. Over the course of the study, 51 people suffered coronary events: 28 deaths and 23 heart attacks.
And the result: over a 10-year period, 78.5% of patients with cardiovascular disease who did not indicate an angry personality profile had infarction free-survival compared with 57.4% of similar patients who exhibited anger profiles. Statistically, this result is highly significant, and the length of the study period increases the confidence that the finding is real, not a statistical fluke.
The second paper looked at the other side of the coin. Dr Michael Miller of the University of Maryland, Baltimore, has studied and published for over a decade the effect of laughter on survival after a myocardial infarction. His data indicated that when people laugh, their brachial arteries dilate as measured by the brachial artery reactivity test (BART). (The brachial artery courses along the humerus, the bone of the upper arm). When faced with mental stress, those arteries constrict. For example, the participants’ blood vessels opened wider when volunteers watched scenes from the farce There’s Something About Mary. But blood vessels tended to constrict when participants watched the graphic violence of the drama Saving Private Ryan. The difference ranged from 30% to 50% in diameter.”The magnitude of change we saw in the endothelium after laughing was consistent and similar to the benefit we might see with aerobic exercise or statin use,” Miller said.
Now, this is impressive –laughter having an effect that is similar to aerobic exercise! How could that be? Actually, the explanation is quite obvious. Both exercise and laughter cause the release of endorphins, and those cause the release of a gas –nitrous oxide (yes, the “laughing gas”)- by the endothelial cells that line the blood vessels, which causes them to dilate.
But wait, there is more
Laughter has been shown to release hormones and peptides that suppress inflammation. Now, inflammation is a bad, bad actor. It causes the formation of atherosclerotic plaques in the arteries, which in turn cause heart disease. But that’s not all: inflammation is an important factor in the formation and spread of many cancers. Even the aging process is associated with inflammation. Is it any wonder then that happy people live longer?
This feels like an infomercial, but truly –there is more. Laughter stimulates lymphocytes that are called “Natural Killer cells”, or NK cells. Now the imagery of thuggish, born killers is quite unfair. They indeed prowl the neighborhood in search of a victim, but the victims are virus-infected cells and cancer cells. The NK cells are our first line of defense against viral infection and cancer, and laughter increases both their numbers and activity.
How does it work?
We already stated that laughter releases endorphins and other hormones. It also activates the parasympathetic nervous system and suppresses the sympathetic system. These two systems have a Ying and Yang relationship. The sympathetic system causes release of adrenaline, and increases the blood pressure and heart rate. The parasympathetic system does exactly the opposite –it causes the release of acetylcholine, which counteracts all the effects of adrenaline. Just think of the sympathetic as the quintessential New York high-strung system, and the parasympathetic as the California laid-back one.
Now we are beginning to see how the brain can affect health. But the mind–body interaction is infinitely more complex than that. There is no “laugh center” in the brain. Many areas and circuits of the brain are involved. Among others, the amygdala, which coordinate emotional responses; the hippocampus, which stores information and coordinates memory; and the prefrontal cortex, the executive center of the brain, which integrates all the inputs coming in from the various regions of the brain. But this is a partial list only. fMRI studies show widespread activation of many areas, including the auditory and visual centers.
Here is an interesting observation. Students who were exposed to a humorous video before taking a test did much better than students who viewed a video depicting a sad situation, or students who did not view any video before taking the test.
Another study showed that subjects were more creative when shown a funny video than when they were shown a sad one. The common finding in both experiments: fMRI showing widespread activation of many areas in the brain; which in turn allows the brain to make unexpected and unusual connections –the very essence of creativity.
So how do we start laughing?
Several years ago I watched on TV a segment about an Indian physician, Dr. Madan Kataria, who started a Yoga Laughter club with 5 people. They just got together and started laughing. It started a bit awkward, restrained. But within minutes their laughter became louder, more hearty, more uproarious. I first watched in disbelief, then smiled, and finally started laughing at, and then with, the people. It became infectious. So what happened?
Paul Ekman, a psychologist at UCSF, has been studying the connection between the brain and facial muscles. What he discovered is that the connection is bidirectional. The brain controls the facial muscles involved in laughter, and vice versa –activation of the facial muscles involved in laughing will activate the appropriate areas of the brain. So that must be the biological basis for the laughing clubs, now numbering more than 6000 in 60 countries. These people genuinely feel happy by activating the laughter areas through their laughter muscles.
What a happy demonstration of mind–body connection.
So when you get up in the morning –smile, may be even laugh out loud. It will make your day, and maybe prolong your life.
Dov Michaeli, MD, PhD is a basic researcher who writes on the life sciences at The Doctor Weighs In.
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