Institute of Neuroscience and Mental Health, MRC Centre for Neuropsychiatric Genetics and Genomics, Henry Wellcome Building, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom.
Biol Psychiatry. 2013 Apr 1;73(7):691-8. doi: 10.1016/j.biopsych.2012.09.032. Epub 2012 Nov 28.
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).
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.
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).
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.
磁共振波谱（MRS）研究一致表明，重度抑郁症患者的皮质 γ-氨基丁酸（GABA）浓度降低。然而，关于缓解期持续存在缺陷的证据是模棱两可的，这表明 GABA 功能障碍可能是抑郁的一个潜在特征标志物。尽管 MRS 测量 GABA 的总浓度，但脑磁图提供了神经活动的直接测量值，皮质 γ 振荡由 GABA 能抑制性中间神经元的活动塑造。在这项研究中，我们调查了缓解期抑郁症（RD）患者与从未抑郁的对照组（ND）患者的 γ 振荡和 GABA 浓度是否存在差异。
招募了 37 名健康、未用药的女性志愿者（n = 19 RD，n = 18 ND）。通过时频分析量化了视觉皮层中由简单光栅刺激诱导的 γ 振荡频率和幅度。MEGA-PRESS 差谱中从前额叶、枕叶和皮质下体积中分辨出 GABA/谷氨酸+谷氨酰胺的 MRS 峰。
RD 和 ND 个体的亚临床抑郁症状频率没有差异。ND 年龄稍大（平均 23 岁 vs. 21 岁），但年龄与依赖指标无关。GABA 水平或诱导的皮质 γ 测量值没有组间差异，但 RD 个体的模式起始诱发反应的 M80（C1）成分明显减少（减少 46%，Cohen's d = 1.01，p =.006）。
RD 患者的 GABA 系统的 MRS 和脑磁图测量均正常。然而，早期视觉诱发电位可能是该疾病的潜在特征标志物。
