A long-term prospective evaluation of first-degree relatives of panic patients who underwent the 35% CO2 challenge

Biol Psychiatry. 1999 Feb 1;45(3):365-7. doi: 10.1016/s0006-3223(98)00030-4.


Background: This follow-up study investigated the potential priming effect of the 35% CO2 challenge on the development of anxiety disorders and/or panic attacks in healthy first-degree relatives of panic patients across a period of 3-4 years subsequent to the challenge.

Methods: Thirty-one relatives who underwent the 35% CO2 challenge 3-4 years before and 14 relatives, free from psychiatric diagnoses in the same period, were directly reevaluated for the presence of anxiety disorders and panic attacks.

Results: None developed anxiety disorders and only 1, among relatives previously tested with the 35% CO2 challenge, reported sporadic panic attacks.

Conclusions: The 35% CO2 challenge is a safe research paradigm in the investigation of healthy subjects with a familial vulnerability to panic, and CO2 hypersensitivity might be considered a trait marker of an underlying familial vulnerability to panic disorder.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Anxiety / chemically induced*
  • Carbon Dioxide* / adverse effects
  • Chi-Square Distribution
  • Double-Blind Method
  • Family Health
  • Female
  • Follow-Up Studies
  • Genetic Predisposition to Disease
  • Humans
  • Male
  • Middle Aged
  • Panic Disorder / chemically induced*
  • Panic Disorder / genetics
  • Panic Disorder / physiopathology
  • Prospective Studies
  • ROC Curve
  • Time Factors


  • Carbon Dioxide