Caffeine and 35% carbon dioxide challenge tests in panic disorder

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 I week interval. A panic attack was induced in 51 2 (61.4%) patients during the C02 test (chi(2) = 31.67, df = 1, p < 0.00 1) and in 38 (45.8%) patients during the caffeine test (chi(2) = 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 (chi(2) = 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 (chi(2) = 20.34, df = 1, p = 0.019), less previous alcohol abuse (chi(2) = 23.42, df = 1, p < 0.00 1), and had more previous depressive episodes (chi(2) = 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. Copyright (c) 2007 John Wiley & Sons, Ltd.