Serum Tau and α‐Synuclein in Children With Attention‐Deficit/Hyperactivity Disorder: Cross‐Sectional Associations With Methylphenidate Treatment

OBJECTIVE: To compare serum total tau and α-synuclein among controls, drug-naïve children with attention-deficit/hyperactivity disorder (ADHD) and children with ADHD receiving methylphenidate. METHODS: Original ELISA spreadsheets provided 26 controls, 29 evaluable drug-naïve participants and 32 methylphenidate-treated participants. Boundary-coded results (> 500 pg/mL for tau; < 938 pg/mL for α-synuclein) were assigned the recorded boundary for rank-based analyses. Groups were compared using Kruskal-Wallis tests and Dunn-Bonferroni contrasts; within-group associations used Spearman correlations. RESULTS: = 0.101); drug-naïve ADHD had lower tau than controls, whereas the treated group differed from neither comparator after correction. The α-synuclein-tau correlation remained significant after false-discovery-rate adjustment only in drug-naïve ADHD (ρ = 0.443, adjusted p = 0.048). CONCLUSIONS: Serum α-synuclein and total tau showed distinct cross-sectional group patterns. These associations do not establish methylphenidate effects and require prospective confirmation.