Many cultures around the world have numbers which they believe to be unlucky. The number 13, for instance, is the subject of superstitious fear among cultures in the British Isles. Even Americans are aware of this phenomenon - “Friday the 13th” is a day so associated with bad luck that it was chosen as the subject of a popular horror movie. In a study published in the British Medical Journal, Phillips et al explored the possibility that psychological stress associated with unlucky numbers can actually affect the timing of fatal heart attacks.

For their study, the authors chose Chinese and Japanese Americans, who have a superstitious fear regarding the number four. This fear may stem from the similarity in the way the word “four” is pronounced with the word “death” in Mandarin, Cantonese, and Japanese. Just as some buildings in Ireland lack a floor designated 13, so some Chinese and Japanese hospitals lack a fourth floor, or a room with the number four. The authors also point out that in mainland China, the number four is not used when designating military aircrafts, and that Chinese and Japanese restaurants in the United States avoid using it in their phone numbers.

To carry out this study, the death records of Chinese and Japanese Americans were examined. Each of these records were compared to twelve records of white Americans of the same age, sex, state of residence, marital status, inpatient status, and cause of death. The results? In Chinese and Japanese patients with a history of chronic heart disease and who had died of heart-related causes, deaths were significantly more frequent on the fourth day of the month than any other day. This trend was not observed in white patients. No plausible alternative explanations, such as cultural behavioral changes around the fourth, were found.

The authors termed this peak in mortality “The Baskerville Effect,” after the famous fictional tale in which a man suffers a fatal heart attack from the psychological stress associated with a superstition. The authors keenly note that Sir Arthur Conan Doyle, who wrote The Hound of the Baskervilles, was a physician as well as a storyteller - perhaps he, too, observed this strange and intriguing phenomenon.

Reference:
Heart Attacks, diagnosisheart.com