Photo by nosha, via Flickr
Photo by nosha, via Flickr
ScienceOnly Human

When Laughter Isn’t Funny

This Sunday is World Laughter Day, a 16-year-old holiday puffed into existence by the guy who created something called “laughter yoga.” That means that all weekend long we’re going to be bombarded with articles about the benefits of laughter. Didn’t you know? Laughter is good for your arteries, it boosts the success rate of IVF, and even treats cancer!

I have nothing against laughing, I even do it occasionally. But when it comes to the science of laughter, some of the most interesting studies are those describing medical cases in which laughter foretold sickness.

I’ll describe three of them here, all published last year:

Take the case of a 52-year-old woman who had been suffering from intense laughter-induced headaches for 32 years. A scan of her brain revealed three “giant Pacchionian granulations,” or pockets of pooled cerebrospinal fluid. This is an example of what the researchers call a “circumstantial headache.” It wasn’t caused by anything special about laughter, per se, but presumably something about the changes in fluid pressure that the laughter caused. Tellingly, when the woman sneezed or coughed it also led to headaches. She refused any further treatment for the granulations, “given that her laughing headache was avoidable.” (Bitter pill!)

Or how about the 43-year-old man with bipolar disorder who had seizures after laughing at comedy shows on television. “In each instance, he started laughing, then his arms started shaking and he felt like ‘his consciousness was being vacuumed away’,” his doctors write. “He had had a variable number of seizure episodes; five times a day on average, based upon the length and intensity of the comedy shows.” His doctors couldn’t find anything overtly wrong with him, so at first they attributed the seizures to his bipolar disorder. But then they monitored him for two days with electroencephalography (EEG), which measures brain-wave activity through harmless scalp electrodes. The EEG charts showed that the seizures were caused by his “deep-belly laughing.”

Laughter is thought to come about from activity in two distinct brain areas: the temporal lobe, which processes the emotional aspects, and the frontal cortex, which handles the motor component. The researchers hypothesized that the man’s laughter spurred seizures in the motor area, but couldn’t be sure. They put him on a new seizure medication and it fixed the problem. If that hadn’t worked, though, the man would have had to stop watching TV. “As only limited data exist, clinicians must recommend a multimodal treatment,” they write, including “laugh-provocation avoidance.”

Finally, consider the 58-year-old man who was playing charades with his family one night when he suddenly couldn’t stop laughing. He didn’t worry about it too much until the next time it happened — at a funeral. “He laughed throughout the service without any cause, and was profoundly embarrassed,” his doctors write. It happened a third time when he was visiting his sick mother. These incidents, known in the medical literature as “pathological laughter” or PL, “caused him to retire from social contact.”

Pathological laughter, it turns out, has been linked to multiple sclerosis, brain tumors, Alzheimer’s disease, Pick’s disease and Wilson’s disease. It can also be a delayed sign of a stroke, which was the case for this man. Brain imaging showed lesions in white matter, which connects brain cells, as well as in the midbrain and the temporal lobe. Nobody knows what causes pathological laughter, but because of the delayed response, researchers speculate that it’s not simply the result of the lesions. “Delayed PL reflects the time required for the formation of autonomous motor centres,” they write. “It has been suggested that there is formation of new neuronal activity or new laughter control centres.”

The man’s laughing fits went away, somewhat ironically, after he began taking citalopram, an antidepressant.