Effect of nicotine on 35% CO2 induced anxiety. A study in healthy volunteers

Panic Disorder and cigarette smoking co-occur at a rate that exceeds chance significantly. Theoretically, cigarette smoking may: a) attenuate panicky symptoms via cognitive factors or pharmacological action; b) contribute to the development of panic disorder; and/or c) share an etiologic vulnerability with panic. As things are not that clear-cut and experimental researches in humans are poor, the present study is aimed at testing whether nicotine has a direct influence on laboratory-elicited panic in human volunteers. Methods. According to a placebo-controlled, double-blind, randomized, cross-over design 33 healthy non smokers underwent a 35% CO2 challenge after the transdermal administration of a nicotine patch on one test day and of a placebo patch on another test day. Physiological measures (blood pressure, heart rate) and rating scale scores (Panic Symptom List, Visual Analogue Scale of Anxiety, State-Trait Anxiety Inventory) were assessed. Results. Compared to the placebo condition, nicotine increased diastolic blood pressure (p < .1), heart rate (p < .001) and PSL scores (p < .005) prior to the CO2 challenge but did not affect responding to the CO2 challenge itself. Discussion. The increase of physiological variables before the challenge seems due to the nicotine caused autonomic activation. The present study do not evidence any effect of nicotine on laboratory elicited panic. Conclusion. In the present study nicotine failed to affect experimental panic, replication in a clinical sample will be warranted.