Randomised trial, 1995
Does menstrual cycle phase affect anxiety response to CO2 in women with panic disorder?
Yes. Women with panic disorder showed significantly stronger anxiety during the early follicular phase than the luteal phase after breathing a CO2 mixture. Controls showed no anxiety response.
What they did
In a double-blind crossover study, 10 women with panic disorder and 7 control women breathed a mixture of 35% carbon dioxide and 65% oxygen during two phases of their menstrual cycle: early-follicular and midluteal. Anxiety was measured after the inhalation.
What they found
In women with panic disorder, anxiety after CO2 inhalation was significantly stronger during the early-follicular phase than the midluteal phase. Control women had no anxiety reactions to the CO2 at either phase.
What it means for you
Menstrual cycle hormones may increase how sensitive women with panic disorder are to CO2, triggering stronger anxiety. This suggests panic symptoms might worsen during the early follicular phase of the cycle. The main limits are the very small sample and that breathing CO2 in a lab may not reflect real-world panic attacks.
10
Women with panic disorder
7
Control women
35%
CO2 concentration
About the study
- Original title
- Menstrual cycle-related sensitivity to 35% CO2 in panic patients
- Authors
- Perna G, Brambilla F, Arancio C et al.
- Journal
- Biological psychiatry
- Year
- 1995
- Study design
- Randomised trial
- Participants
- 10
- What was tested
- Inhalation of 35% CO2 and 65% oxygen
- Read the paper
- doi.org/10.1016/0006-3223(94)00154-u
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