Increased Plasma Kynurenic Acid Levels are Associated with Impaired Attention/Vigilance and Social Cognition in Patients with Schizophrenia

Xingbing Huang, 1, 2,* Wenhua Ding, 2,* Fengchun Wu, 2 Sumiao Zhou, 2 Shuhua Deng, 2 Yuping Ning 1– 3 1First School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong, People’s Republic of China; 2The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, Guangdong, People’s Republic of China; 3Guangdong Engineering Technology Research Center for Translational Medicine of Mental Disorders, Guangzhou, Guangdong, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yuping Ning 36 Mingxin Road, Liwan District, Guangzhou, People’s Republic of ChinaTel +86 20 8189 1425Fax +86 20 8189 1391Email ningjeny@126.comObjective: Preclinical studies have reported that abnormal kynurenic acid (KYNA) may play a role in cognitive deficits. Schizophrenia (SCZ) is characterized by a wide range of cognitive deficits that may evolve from abnormal KYNA. This study aimed to explore the relationship between KYNA and cognitive impairment in SCZ, which has not yet been reported.Methods: We recruited 30 SCZ patients and 34 healthy controls, measured clinical symptoms by using the Positive and Negative Syndrome Scale and performed cognitive tests using the MATRICS Consensus Cognitive Battery (MCCB). Plasma levels of tryptophan, kynurenine, and KYNA were determined by high-performance liquid chromatography–tandem mass spectrometry.Results: We found that plasma KYNA levels were significantly higher in patients than in healthy controls (p=0.009). The cognitive performance of patients in the total MCCB scores and the scores of all subscales were significantly lower than those in healthy controls (all P < 0.01). Correlation analysis showed that KYNA levels were negatively correlated with attention/vigilance (r=– 0.457, p=0.019) and social cognition (r=– 0.481, p=0.013) only in SCZ patients.Conclusion: Our results ind