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Neurobiology of Panic Disorder

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Neurobiology of Panic Disorder

"There is most evidence for changes in Gamma-aminobutyric acid, with lowered cortical Gamma-aminobutyric acid type levels measured by magnetic resonance spectroscopy, and diminished benzodiazepine-receptor binding in the parietotemporal regions in unmedicated patients with panic disorder (Hasler et al., 2008)."

This happens in panic disorder. Gamma-aminobutyric acid is the major inhibitory neurotransmitter in the brain. Benzodiazepine also binds to Gamma-aminobutyric acid type A receptors and increases its firing rate, thus resulting in hyperpolarisation of the cell because of increased chloride influx. So, specific regions in the brain are hyperexcitable in patients with panic disorder.

Summary of Hasler et al. 

Context

Studies have implicated the benzodiazepine receptor system in the pathophysiologic mechanism of panic disorder  by indirect evidence from pharmacological challenge studies and by direct evidence from single-photon emission computed tomography and positron emission tomography neuroimaging studies
  1. The benzodiazepine receptor binding potential was decreased in multiple areas of the frontal, temporal, and parietal cortices and was increased in the hippocampus/ parahippocampal region in subjects with panic disorder vs controls
  2. The most significant decrease was in the dorsal anterolateral prefrontal cortex; the most significant increase in the hippocampus/parahippocampal gyrus
  3. In subjects with panic disorder, the severity of panic and anxiety symptoms correlated positively with benzodiazepine receptor binding in the dorsal anterolateral prefrontal cortex but negatively with binding in the hippocampus/parahippocampal gyrus
  4. These data provide evidence of abnormal benzodiazepine–Gamma-aminobutyric acid type A receptor binding in panic disorder, suggesting that basal and/or compensatory changes in inhibitory neurotransmission play roles in the pathophysiologic mechanism of panic disorder. 

Hasler G, Nugent AC, Carlson PJ, Carson RE, Geraci M, Drevets WC. Altered cerebral gamma-aminobutyric acid type A-benzodiazepine receptor binding in panic disorder determined by [11C]flumazenil positron emission tomography. Arch Gen Psychiatry. 2008;65(10):1166-1175. doi:10.1001/archpsyc.65.10.1166
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  1. Justpsychiatry12 January 2021 at 20:25

    Hasler G, Nugent AC, Carlson PJ, Carson RE, Geraci M, Drevets WC. Altered cerebral gamma-aminobutyric acid type A-benzodiazepine receptor binding in panic disorder determined by [11C]flumazenil positron emission tomography. Arch Gen Psychiatry. 2008;65(10):1166-1175. doi:10.1001/archpsyc.65.10.1166

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