Global cerebral blood flow after CO2 inhalation in normal subjects and patients with panic disorder determined with [15O]water and PET.

OBJECTIVE

To determine the effect of CO2 inhalation on global cerebral blood flow (gCBF) and pCO2-adjusted gCBF in normal subjects and panic disorder patients.

METHOD: Global cerebral blood flow was determined using quantitative [15O] water imaging in normal subjects (n = 12) and panic disorder patients (n = 14) after inhalations of medical grade air and of 35%/65% CO2/O2 mixture, a known inducer of panic. The gCBF was calculated as an area-weighted mean value. The pCO2 -adjusted gCBF values were calculated based on the formula of Reiman et al. [Am. J. Psychiatr. 143 (1986) 469]. Data were analyzed using repeated-measures ANOVA and regression analyses.

RESULTS

The pCO2 values did not differ statistically between normals and panic patients. Panic patients exhibited a decrease in gCBF and stable pCO2-adjusted gCBF values in comparisons of AIR and CO2 inhalations, whereas normals exhibited stable gCBF and increasing pCO2-adjusted gCBF values.

CONCLUSIONS

Patients with panic disorder, especially when symptomatic, exhibited an abnormal pattern in gCBF response to provocation.