A Predictor of PTSD?

Provocation of anxiety by inhaled CO₂ has been observed in panic disorder and some other anxiety disorders; findings in post-traumatic stress disorder (PTSD) have been inconsistent. These investigators aimed to determine whether CO₂ response would predict the development of combat-related PTSD. They administered a single inhalation of 35% CO₂ to 158 soldiers who had not been deployed previously and who were scheduled to deploy to Iraq within 3 months (mean age, 24; 72% white).

Response to CO₂ inhalation ranged from none (32% of participants) to panic (11%). Once deployed, soldiers completed Web-based monthly ratings of combat stressors (e.g., incoming fire), PTSD symptoms, depression and “anxiety/stress symptoms” (mean deployment, 13 months)…