title: Anxiety sensitivity and expectation of arousal differentially affect the respiratory response to caffeine.
abstract: BACKGROUND
  This study aimed to test how expectations and anxiety sensitivity influence respiratory and autonomic responses to caffeine.
  
  
  OBJECTIVE
  The current study investigated the effects of expected vs. unexpected caffeine ingestion in a group of persons prone to the anxiety-provoking effect of caffeine (high anxiety sensitive persons, that is, persons scoring at least one SD above the mean on the Anxiety Sensitivity Index (Peterson and Reiss 1992)) as compared to low-anxious controls.
  
  
  METHODS
  Autonomic arousal (heart rate, skin conductance level), respiratory responding (expired CO2, minute ventilation), and subjective report were assessed in high and low anxiety sensitive participants immediately after beverage consumption and at absorption peak (30 min post-consumption) in four separate sessions during which either coffee (expectation of caffeine) or bitter lemon soda (no expectation of caffeine) was crossed with 4 mg/kg caffeine vs. no drug.
  
  
  RESULTS
  High and low anxiety sensitive persons showed comparable autonomic arousal and symptom reports to caffeine which was modulated by expectation, i.e., greater for coffee. Respiratory responding (CO2 decrease, minute ventilation increase) was more accentuated when caffeine was both expected and administered in the low anxiety sensitive group but more accentuated when caffeine was unexpectedly administered in the high anxiety sensitive group. Autonomic arousal and respiratory effects were observable within a few minutes after caffeine administration and were most pronounced at maximum absorption.
  
  
  CONCLUSIONS
  The results highlight the modulating role of expectancies in respiratory responding to caffeine in low vs. high anxiety sensitive persons and might have important implications for the better understanding of unexpected panic attacks.
authors.affiliation: Department of Physiological and Clinical Psychology/Psychotherapy, University of Greifswald, Franz-Mehring-Str. 47, 17487, Greifswald, Germany, christiane.pane-farre@uni-greifswald.de.
authors.forename: Christiane A
authors.initials: CA
authors.lastname: Pané-Farré
authors.forename: Manuela G
authors.initials: MG
authors.lastname: Alius
authors.forename: Christiane
authors.initials: C
authors.lastname: Modeß
authors.forename: Karen
authors.initials: K
authors.lastname: Methling
authors.forename: Terry
authors.initials: T
authors.lastname: Blumenthal
authors.forename: Alfons O
authors.initials: AO
authors.lastname: Hamm
mesh_terms: D000328:Adult; D001007:Anxiety / Q000503:physiopathology* / Q000523:psychology*; D001143:Arousal / Q000187:drug effects* / Q000502:physiology*; D001341:Autonomic Nervous System / Q000187:drug effects / Q000503:physiopathology; D001794:Blood Pressure / Q000187:drug effects; D002110:Caffeine / Q000494:pharmacology*; D003469:Culture; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D056152:Respiratory Rate / Q000187:drug effects* / Q000502:physiology*; D055815:Young Adult
chemical_list: D002110:Caffeine