Differential thalamic GSH/Glu ratios Among primary headache subtypes and clinical implications: A cross-sectional magnetic resonance spectroscopy study

Background Glutathione (GSH) and glutamate (Glu) have been individually implicated in migraine pathophysiology, but their ratio as a marker of oxidative–excitatory balance in the thalamus—a key pain-processing hub—remains unexplored. This study investigated thalamic GSH/Glu ratios across primary headache subtypes and evaluated their diagnostic utility. Methods This cross-sectional study included 131 participants: 36 healthy controls (HC), 17 migraine with aura (MwA), 46 migraine without aura (MwoA), and 32 tension-type headache (TTH). Single-voxel proton magnetic resonance spectroscopy was performed at 3T using a MEGA-PRESS sequence targeting bilateral thalami. Metabolite concentrations were quantified with LCModel and corrected for partial volume effects using an established tissue correction framework. Group differences were analyzed using ANOVA with Tukey HSD correction; diagnostic performance was assessed using ROC analysis with bootstrap resampling. Results The GSH/Glu ratio differed significantly across groups (F = 9.41, p < 0.001, η 2 = 0.183), confirmed by bootstrap validation. MwA (0.250 ± 0.038, p < 0.001, Cohen's d = 1.47) and MwoA (0.280 ± 0.052, p = 0.006, d = 0.79) showed significantly lower ratios than HC (0.320 ± 0.055), whereas TTH (0.318 ± 0.068) did not differ from HC. This reduction was driven by decreased GSH levels, with Glu concentrations unchanged across groups. Exploratory ROC analysis yielded apparent AUCs of 0.874 for GSH and 0.758 for the GSH/Glu ratio; these estimates require independent validation. Conclusions Migraine is characterized by reduced thalamic GSH levels and decreased GSH/Glu ratios, reflecting diminished antioxidant buffering capacity against normal excitatory neurotransmission. This metabolic alteration distinguishes migraine from TTH, supporting distinct pathophysiological mechanisms.