Shaw, Alexander ![]() ![]() ![]() ![]() |
Abstract
Background: Magnetic resonance spectroscopy (MRS) studies have consistently demonstrated reduced cortical γ-aminobutyric acid (GABA) concentrations in individuals with major depression. However, evidence for a persistent deficit during remission, which would suggest that GABA dysfunction is a possible trait marker of depression, is equivocal. Although MRS measures total concentration of GABA, magneto-encephalography provides direct measures of neural activity, with cortical γ oscillations shaped by the activity of GABAergic inhibitory interneurons. In this study we investigated whether γ oscillations and GABA concentrations would differ in individuals with remitted depression (RD) compared with never depressed control subjects (ND). Methods: Thirty-seven healthy, unmedicated female volunteers (n = 19 RD, and n = 18 ND) were recruited. The γ oscillation frequencies and amplitudes in the visual cortex, induced by simple grating stimuli, were quantified with time-frequency analyses. Distinct GABA/glutamate + glutamine MRS peaks were resolved from MEGA-PRESS difference spectra in prefrontal, occipital, and subcortical volumes. Results: The RD and ND individuals did not differ in the frequency of subclinical depressive symptoms. The ND were slightly older (mean = 23 years vs. 21 years), but age did not correlate with dependent measures. There were no group differences in GABA levels or induced cortical γ measures, but RD individuals had markedly reduced M80 (C1) components of the pattern-onset evoked response (46% reduction, Cohen’s d = 1.01, p = .006). Conclusions: Both MRS and magneto-encephalography measures of the GABA system are normal in RD. However, the early visual evoked response is a potential trait marker of the disorder.
Item Type: | Article |
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Date Type: | Publication |
Status: | Published |
Schools: | MRC Centre for Neuropsychiatric Genetics and Genomics (CNGG) Cardiff University Brain Research Imaging Centre (CUBRIC) Psychology Neuroscience and Mental Health Research Institute (NMHRI) Medicine |
Subjects: | B Philosophy. Psychology. Religion > BF Psychology |
Uncontrolled Keywords: | Biomarker; C1; depression; GABA; γ; MEG; MRS; neuroimaging; trait; visual evoked response |
Publisher: | Elsevier |
ISSN: | 0006-3223 |
Funders: | Wales Institute of Cognitive Neuroscience |
Last Modified: | 05 Aug 2023 01:05 |
URI: | https://orca.cardiff.ac.uk/id/eprint/44406 |
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