Serum Complement Component 4A and Neurofilament Light Chain Levels Before and After Risperidone Monotherapy in Patients With Psychosis.

Objective

Recently, complement component 4A (C4A), a complement system protein, and neurofilament light chain (NfL), a neuroaxonal injury biomarker, have been found to be potentially implicated in the pathophysiology of psychosis. This study evaluated C4A and NfL levels before and after risperidone monotherapy in patients with psychosis.

Methods

This prospective observational study included 30 patients (18-45 years) with psychosis diagnosed according to DSM-5 criteria and 30 healthy controls. Patients received risperidone monotherapy and were followed up for 8 weeks. Serum C4A and NfL levels were measured before and after 8 weeks of treatment in patients using enzyme-linked immunosorbent assay (ELISA). In healthy controls, C4A and NfL levels were also measured once. Quality of life was assessed using the World Health Organization Quality of Life Brief Version (WHOQOL-BREF) questionnaire.

Results

Serum NfL levels were significantly (p < 0.001) higher, whereas serum C4A levels were not significantly higher in psychosis patients as compared to healthy controls. After 8 weeks of risperidone treatment, serum NfL levels did not change significantly, whereas serum C4A levels decreased significantly (p < 0.001). WHOQOL-BREF domain scores improved significantly (all p < 0.001) across all domains in psychosis patients.

Conclusions

The preliminary findings of the study suggest that risperidone monotherapy resulted in a significant reduction in serum C4A levels, whereas serum NfL levels did not change and remained elevated in patients with psychosis. In addition, risperidone monotherapy resulted in a significant improvement in quality of life. Serum C4A and NfL levels were measured using ELISA rather than ultrasensitive immunoassays. Therefore, larger longitudinal studies with longer follow-up and ultrasensitive biomarker platforms are warranted to confirm these findings.