title: Caffeine and 35% carbon dioxide challenge tests in panic disorder.
abstract: Our aim was to compare the demographic and clinical features of panic disorder (PD) patients with agoraphobia-DSM-IV-who had a panic attack after both an oral caffeine and the 35% carbon dioxide (CO2) challenge tests (responsive group) and compare them with PD patients who did not have a panic attack after both tests (non-responsive group). We examined 83 PD patients submitted to a 35% CO2 test and to an oral caffeine (480 mg) intake within 1 week interval. A panic attack was induced in 51 (61.4%) patients during the CO2 test (chi2=31.67, df=1, p<0.001) and in 38 (45.8%) patients during the caffeine test (chi2=18.28, df=1, p=0.023). All patients who had a panic attack during the caffeine test also had a panic attack during the CO2 test (n=38)-responsive group. The responsive had more (chi2=24.55, df=1, p=0.008) respiratory PD subtype, disorder started earlier (Mann-Whitney, p<0.001) had a higher familial prevalence of PD (chi2=20.34, df=1, p=0.019), less previous alcohol abuse (chi2=23.42, df=1, p<0.001), and had more previous depressive episodes (chi2=27.35, df=1, p<0.001). Our data suggest that there is an association between respiratory PD subtype and hyperreactivity to challenge tests: CO2 and oral caffeine.
authors.affiliation: Laboratory of Panic & Respiration, Institute of Psychiatry, Federal University of Rio de Janeiro, Brazil. antonionardi@terra.com.br
authors.forename: Antonio E
authors.initials: AE
authors.lastname: Nardi
authors.forename: Alexandre M
authors.initials: AM
authors.lastname: Valença
authors.forename: Fabiana L
authors.initials: FL
authors.lastname: Lopes
authors.forename: Valfrido L
authors.initials: VL
authors.lastname: de-Melo-Neto
authors.forename: Rafael C
authors.initials: RC
authors.lastname: Freire
authors.forename: Andre B
authors.initials: AB
authors.lastname: Veras
authors.forename: Isabella
authors.initials: I
authors.lastname: Nascimento
authors.forename: Anna Lucia
authors.initials: AL
authors.lastname: King
authors.forename: Gastão L
authors.initials: GL
authors.lastname: Soares-Filho
authors.forename: Marco A
authors.initials: MA
authors.lastname: Mezzasalma
authors.forename: Walter A
authors.initials: WA
authors.lastname: Zin
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000379:Agoraphobia / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D002110:Caffeine; D002245:Carbon Dioxide; D000697:Central Nervous System Stimulants; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016584:Panic Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D011569:Psychiatric Status Rating Scales; D012959:Socioeconomic Factors
chemical_list: D000697:Central Nervous System Stimulants; D002245:Carbon Dioxide; D002110:Caffeine