Re: Laughter and MIRTH (Methodical Investigation of Risibility, Therapeutic and Harmful): narrative synthesis
"Laughter in any form carries a low risk of harm and may be beneficial" concluded the study's authors, Ferner and Aronson. Unfortunately, while the distinguished authors addressed the harms of laughter for the laugher, they paid less attention to the potential health (and other) hazards for the listener.
Exposure to Annoying Laughter (EAL) has long been known as a potential risk of human communication, and as laughter has gained popularity in recent years, widely promoted by the comedy industry, its unfavorable results emerged. A ubiquitous phenomenon in our society, EAL was also depicted on television screens and in different sitcoms, such as Friends (by the notorious laugher, Janice),Seinfeld (one of Jerry Seinfeld's girlfriends had a laugh that sounded like "Elmer Fudd sitting on a juicer") and others. Whether spousal EAL or other social exposure, little is known about the epidemiology of EAL, the unique voice patterns that produce its unpleasant stimuli and their obnoxious interaction with alcohol or other substances.
Thus, when the benefit of laughter is modest and the margin to adverse events is narrow, one has to plan a careful examination for adverse effects as part of the protocol of the review. In this case a thorough search of the literature, including grey literature and ongoing trial databases is warranted along with an assessment of reporting bias. Until then, I believe that prudent clinicians should guide patients to laugh in private, to embrace the voiceless parts of their laughter or to just say LOL.
Competing interests: One of my classmates had a hideous laughter, and I've experienced numerous attacks of EAL. I think I have a decent laughter (some listeners claim that I suffer paroxysmal seal-like laughter).