title: Mass hysteria among student performers: social relationship as a symptom predictor.
abstract: OBJECTIVE
  In April 1989 an outbreak of illness suddenly afflicted student performers in Santa Monica, Calif., and an extensive investigation revealed no environmental cause. To clarify the details of the epidemic and determine whether mass hysteria occurred, the authors examined physical, psychological, and social factors that might have contributed to the outbreak.
  
  
  METHODS
  Participating middle- and high-school performers were surveyed; 93% (N = 519) responded; cases were defined as students who had one or more symptoms during the outbreak. A stepwise logistic regression analysis was used to determine significant predictors of illness.
  
  
  RESULTS
  Characteristic features of mass hysteria were present, including preponderance of illness in girls, symptom transmission by sight or sound, presence of hyperventilation, and evidence of psychological or physical stress. Symptomatic and asymptomatic groups differed in frequency of several physical and psychological variables, but observing a friend become sick was the best predictor of the development of symptoms.
  
  
  CONCLUSIONS
  These results confirm earlier research demonstrating multiple psychological and physical factors that contribute to such outbreaks, particularly symptom transmission through social networks. Investigators should explore social transmission as an additional characteristic feature of mass hysteria in order to facilitate early identification of future outbreaks.
authors.affiliation: Department of Psychiatry and Biobehavioral Sciences, UCLA School of Medicine.
authors.forename: G W
authors.initials: GW
authors.lastname: Small
authors.forename: M W
authors.initials: MW
authors.lastname: Propper
authors.forename: E T
authors.initials: ET
authors.lastname: Randolph
authors.forename: S
authors.initials: S
authors.lastname: Eth
mesh_terms: D000124:Achievement; D000293:Adolescent; D000367:Age Factors; D004196:Disease Outbreaks / Q000706:statistics & numerical data; D005260:Female; D006117:Grief; D006801:Humans; D007046:Hysteria / Q000175:diagnosis* / Q000209:etiology / Q000523:psychology; D007100:Imitative Behavior; D008297:Male; D011336:Probability; D012044:Regression Analysis; D012737:Sex Factors; D012919:Social Behavior; D012932:Social Facilitation; D013334:Students / Q000523:psychology*