Letter to the Editor: From discovery to application: Serum 5-hydroxytryptamine for early screening of Parkinson’s complications still faces key challenges

Abstract

Based on 70 patients with Parkinson’s disease, this study by Chen et al, published in the recent issue of the World Journal of Psychiatry, aimed to proposes that serum 5-hydroxytryptamine (5-HT) may simultaneously indicate two key complications: Levodopa-induced dyskinesia and depression. The results showed that serum 5-HT levels were significantly reduced in both groups and remained independent predictors in multivariate analyses, with receiver operating characteristic analyses suggesting a certain degree of discriminative ability. This concept aligns with the clinical need to explain motor and non-motor complications through a shared pathway. However, before it can be incorporated into routine clinical management, external validation, longitudinal studies, standardized measurement, and clearly defined clinical thresholds are still required. Serum 5-HT may serve as one component of risk stratification, but it should not be regarded as a single decisive biomarker.

Keywords: Parkinson‘s disease; 5-hydroxytryptamine; Biomarker; Motor dysfunction; Depression

Core Tip: Reduced serum 5-hydroxytryptamine levels may indicate an increased risk of both dyskinesia and depression in patients with Parkinson’s disease, suggesting its potential role as a unified screening marker for these complications. However, due to limited validation, as well as the absence of robust longitudinal data and standardized assessment protocols, its clinical applicability remains constrained. Therefore, it should be considered only as an adjunctive biomarker rather than a definitive diagnostic or prognostic indicator at the present stage.