Plasma Amino Acid Neurotransmitters and Ischemic Stroke Prognosis: A Multicenter Prospective Study

Background: Plasma amino acid neurotransmitter dysregulation is suggested to be implicated in the development of ischemic stroke, but its prognostic value for ischemic stroke remains controversial. Objective: We aimed to prospectively investigate the associations between plasma amino acid neurotransmitters levels and adverse outcomes after ischemic stroke in a large-scale multicenter cohort study. Methods: We measured 4 plasma amino acid neurotransmitters (glutamic acid, aspartic acid, gamma-aminobutyric acid, and glycine) among 3486 patients with ischemic stroke from 26 hospitals across China. The primary outcome is the composite outcome of death or major disability (modified Rankin Scale score >= 3) at 3 mo after ischemic stroke. Results: After multivariate adjustment, the odds ratios of death or major disability for the highest versus the lowest quartile were 2.04 (95% confidence interval [CI]: 1.60,2.59; P -trend < 0.001) for glutamic acid, 2.03 (95% CI: 1.59, 2.59; P -trend < 0.001) for aspartic acid, 1.35 (95% CI: 1.06, 1.71; P -trend = 0.016) for gamma-aminobutyric acid, and 0.54 (95% CI: 0.42, 0.69; P -trend < 0.001) for glycine. Each standard deviation increment of log-transformed glutamic acid, aspartic acid, gamma-aminobutyric acid, and glycine was associated with a 34%, 34%, and 9% increased risk, and a 23% decreased risk of death or major disability, respectively (all P < 0.05), in a linear fashion as indicated by spline regression analyses (all P for linearity < 0.05). Addition of the 4 plasma amino acid neurotransmitters to conventional risk factors significantly improved the risk reclassification, as evidenced by integrated discrimination improvement and net reclassification improvement (all P < 0.05). Conclusions: Increased glutamic acid, aspartic acid, and gamma-aminobutyric acid and decreased glycine in plasma are associated with adverse out-comes after ischemic stroke, suggesting that plasma amino acid neurotransmitters may be potential intervention targets for improving prognosis of ischemic stroke.