MONDAY, July 9 (HealthDay News) -- Patients with panic disorder have a decrease in benzodiazepine binding sites in the insular cortex compared to those without the psychiatric diagnosis, according to a brain imaging study published in the July issue of the Archives of General Psychiatry.
Oliver G. Cameron, M.D., Ph.D., of the University of Michigan Medical Center in Ann Arbor, and colleagues used positron emission tomography and the benzodiazepine receptor ligand flumazenil labeled with carbon 11 to study the regional brain pattern of receptor binding in 11 patients with anxiety syndrome panic disorder and 21 healthy controls.
Compared to controls, the researchers found that the patients had decreased binding in the insular cortex but not in any other brain region. They also found that patients with panic disorder and comorbid depression had the lowest binding.
"Because γ-aminobutyric acid is a major inhibitory neurotransmitter in the brain and because benzodiazepines facilitate this effect of γ-aminobutyric acid, decreased benzodiazepine binding is consistent with localized brain activation (i.e., loss of inhibition)," the authors conclude. "Because the insula is strongly involved in visceral-somatic afferent and efferent function, activation of the insula is consistent with the occurrence of the physical symptoms prominently associated with panic disorder."
Abstract
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