Increased inosine levels in drug-free individuals with at-risk mental state: A serum metabolomics study

Aim: At-risk mental state (ARMS) has been recently attracting attention with respect to the improvement of the management and outcome of psychiatric diseases, such as schizophrenia. Since only a few studies have reported on biological alterations in ARMS, serum metabolomics was carried out in ARMS subjects and healthy controls using liquid chromatography with high-resolution mass spectrometry.

Methods: Serum samples were collected from ARMS subjects (n = 24; male: 12; female 12) and age- and sex-matched healthy controls (n = 23 male: 11, female: 12). After serum pre-treatment, liquid chromatography with high-resolution mass spectrometry was performed. Multivariate analyses, such as orthogonal partial least-squares discriminant and volcano plot analyses, were performed.

Results: Serum inosine, lactate, taurine, 2,3-dihydroxypropanoate and glutamate levels differed between the two groups. A significant increase in inosine levels was detected in the positive- and negative-ion modes; however, significant differences were not observed in the levels of other purine-related metabolites (hypoxanthine, xanthine and urate) between the two groups.

Conclusion: Increased inosine levels may serve as biological markers for ARMS, in addition to alterations in the levels of lactate and certain amino acids.