title: Effect of laughter on salivary flow rates and levels of chromogranin A in young adults and elderly people.
abstract: OBJECTIVE
  Salivary chromogranin A (CgA) levels and salivary flow rates were measured to evaluate the stress relief effect of laughter on the young and the elderly.
  
  
  METHODS
  Thirty healthy volunteers (15 aged  20-25 years; 15 aged 62-83 years) performed a serial arithmetic task for 15 min and then watched a comedy video for 30 min. On a different day, as a control, they watched a non-humorous video after performing a task similar to the first one. Saliva samples were collected immediately before and after the arithmetic task, 30 min after completing the task (immediately after watching the film), and 30 min after watching the film (60 min after completing mental task). Salivary CgA levels were determined by enzyme-linked immunosorbent assay.
  
  
  RESULTS
  In the elderly group, salivary flow rates, which had declined by the end of the arithmetic task, were statistically significantly higher after watching the comedy video. In the young group, salivary CgA levels, which had increased by the end of the task, had statistically significantly declined after watching the comedy video. No such post-task changes were apparent in control results; in the young group, there was a statistically significant interprotocol difference in salivary CgA levels.
  
  
  CONCLUSIONS
  These findings suggest that laughter may relieve stress, particularly in the young people.
authors.affiliation: Department of Pharmacology, Osaka Dental University, Osaka, Japan. toda-m@cc.osaka-dent.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Toda
authors.forename: Hiroe
authors.initials: H
authors.lastname: Ichikawa
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000032:analysis; D053379:Chromogranin A / Q000032:analysis* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D007564:Japan; D007845:Laughter; D008297:Male; D012463:Saliva / Q000737:chemistry* / Q000502:physiology*; D013315:Stress, Psychological; D055815:Young Adult
chemical_list: D015415:Biomarkers; D053379:Chromogranin A