Medial prefrontal GABA in generalized social anxiety disorder (GSAD)

Abstract

Objectives: GSAD is associated with altered function of medial prefrontal cortex (mPFC), which plays a key role in social cognition and GSAD is responsive to treatments that augment GABA neurotransmission. The aim was to compare mPFC GABA concentrations in GSAD and controls.

Methods: 21 GSAD and 61 healthy age-, sex- and education-matched controls were compared using single voxel magnetic resonance spectroscopy at 3T. Absolute quantification of GABA was derived from a double quantum filter sequence with selective J-refocusing and tissue water measurements.

Results: Liebowitz Social Anxiety Scale scores were 77 ± 17 in GSAD and 13 ± 10 in controls. mPFC GABA was lower (t = 2.8; df = 81; p = .006) in GSAD (0.96 ± .25 mmol) than controls (1.12 ± .22 mmol) independently of a history  of major depressive episodes.

Discussion: The study provides the first evidence for reduced mPFC GABA concentrations in GSAD. The results show that such changes are not specific to major depressive disorder. The data suggest a possible rationale for the efficacy of GABAergic treatments, but it remains to be investigated whether such measures may predict treament response.