Predictive value of kynurenine pathway metabolites in the severity of patients with obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a psychiatric condition characterized by repetitive thoughts and behaviors. The kynurenine pathway has been increasingly implicated in psychiatric disorders. This study aimed to investigate the predictive value of kynurenine pathway metabolites, including serotonin and tryptophan, in patients with varying degrees of OCD.

One hundred fifty OCD patients and 30 healthy controls were included in this study. Patients were divided into mild-moderate, severe, and extremely severe OCD groups based on their Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) scores. Serum levels of serotonin, tryptophan, kynurenine, kynurenic acid, indolamine 2,3-dioxygenase (IDO), tryptophan 2,3-dioxygenase (TDO), 3-hydroxykynurenine, quinolinic acid and picolinic acid were measured using enzyme-linked immunosorbent assay. Logistic regression and receiver operating characteristic (ROC) analysis were performed to evaluate the predictive value of these analytes for OCD severity.

Serotonin and tryptophan levels were significantly decreased in OCD patients compared to healthy controls, while kynurenine pathway metabolites were significantly increased in patients with OCD. Serum levels of kynurenine pathway metabolites increased with severity in OCD patients. As a result of ROC analysis, serotonin, tryptophan and kynurenine pathway metabolites had higher AUC values in distinguishing OCD patients from healthy volunteers, while kynurenine and tryptophan had higher AUC values in distinguishing disease severity.

This study clarifies the role of the kynurenine pathway in the pathophysiology of OCD and suggests that kynurenine pathway metabolites, especially kynurenine, may serve as useful biomarkers to diagnose and differentiate OCD severity. Further research is needed to confirm these findings and explore therapeutic implications.