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In Panic Disorder, Brain pH Unchanged by Hyperventilation

Increased lactate may account for the effect

WEDNESDAY, April 19 (HealthDay News) -- Patients with panic disorder do not experience altered pH levels in the brain during hyperventilation, indicating that increased levels of lactate could act as a buffering mechanism, according to a study published in the April issue of the American Journal of Psychiatry.

Seth D. Friedman, Ph.D., of the University of Washington Medical Center in Seattle, and colleagues studied nine subjects with panic disorder and 11 controls during regulated hyperventilation. Brain pH activity was measured every two minutes using phosphorous spectroscopy. Five scans were taken at baseline, five during regulated hyperventilation and 10 across recovery.

Subjects who had a panic disorder had lower pCO2 during hyperventilation and also had slower pCO2 recovery across the posthyperventilation period. However, there was no significant difference between both groups in terms of increases in brain pH during hyperventilation, or the rate of return of pH to baseline during posthyperventilation. A model derived from data on healthy subjects indicated that the panic disorder had pH blunting.

"Although subjects with panic disorder had greater hypocapnea during hyperventilation, their observed pH response, not altered from comparison levels, implicated exaggerated buffering. It is suggested that increased lactate could account for these findings," the authors conclude.

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