Cigarette smoking and 35% CO2 induced panic in panic disorder patients

A disproportionately large number of persons with panic disorder (PD) smoke cigarettes compared to people in the general population and individuals with other anxiety disorders. Clinical and epidemiological data suggest that cigarette smoking increases the risk for the development and maintenance of PD. The carbon dioxide (CO2) challenge is well established as experimental model for panic. The present study seeks to examine whether cigarette smoking has an influence on laboratory elicited panic in PD patients. Methods: In total 92 subjects (46 smokers and 46 non-smokers) with PD, according to the DSM-IV criteria, were compared. All subjects received a baseline clinical assessment and underwent a 35% CO2 challenge. Response to the challenge was evaluated via the Panic Symptom List and the Visual Analogue Fear Scale. Results: The two samples did not differ on baseline anxiety level. Smokers had a significantly higher increase in panic symptoms in response to the challenge compared to non-smokers (p = 0.04). Limitations: This type of study does not provide information concerning the underlying mechanisms of the link between smoking and panic. Study limitations include lack of formal assessment of personality and of inter-rater reliability. Conclusions: The present findings are consistent with the idea that smoking facilitates panic in PD subjects. This may have clinical implications, as quitting smoking could become one of the relevant steps in the treatment of PD patients.