Many PTSD suffers experience panic disorder or other respiratory altering anxiety conditions. I have encountered several cases people suffering from PTSD being diagnosed with asthma by their general practitioner based on their report of tight chest etc when in fact asthma is not present. Even where a bronchodilator is effective it is not always clear whether it was bronchial dilation fixing the problem or simply that the inhaler reassured them and hence reduced their anxiety. Another explanation, along similar lines, is that those with respiratory anxiety symptoms (common in PTSD) are more likely to focus on breathing and hence have genuine asthma diagnosed, while many cases in the general population remain undiagnosed. I believe there could be a number of explanations for the association that are not necccessarily. I would be interested to know if the study ruled these out?
Therapist P
P.S. I should state that I am not ruling out a causal role and would not be surprised if it were oresent