Laboratory, clinical and therapeutic features of respiratory panic disorder subtype

It is our aim to elaborate on the new developments in regard to the respiratory subtype (RS) of panic disorder (PD) since it was first described. We will present psychopathological features, diagnostic criteria, genetic and physiopathological hypotheses, as well as therapeutic and prognostic characteristics.

Two searches were performed in the Thomson Reuters Web of Knowledge (http://wokinfo.com/): 1 - search terms: "panic disorder" AND ("respiratory symptom" OR "respiratory symptoms" OR "respiratory subtype" OR "respiratory panic" OR "cardiorespiratory"); 2 - all articles citing Briggs and colleagues' 1993 article "Subtyping of Panic Disorder by Symptom Profile" (Br J Psychiatry 1993;163: 201-9). Only those articles involving human subjects and written English were included.

In comparison with patients of the non-respiratory subtype (NRS), RS patients showed greater familial history of PD, and higher comorbidity rates for anxiety disorders and depressive disorders. These patients were also more sensitive to CO2, hyperventilation and caffeine.

Certain characteristics, such as heightened sensitivity to CO2 and the higher incidence of a family history of PD, clearly distinguished the Respiratory Subtype patients from the Non-Respiratory. Nonetheless, some studies failed to demonstrate differential responses to pharmacological treatment and CBT across the subtypes. RS patients seem to respond faster than NRS to pharmacological treatment with antidepressants and benzodiazepines, but more studies are needed to confirm this finding.