RXRA and attention deficit-hyperactivity disorder: No significant between-group difference was noted in the level of PPAR-γ or PPAR-γ coactivator A. Furthermore, RXR-α levels negatively associated with the mean reaction time in the go/no-go task (β = -0.001; Wald χ2 = 0.475; p = 0.029).<h4>Conclusion</h4>To the best of our knowledge, this study is the first to demonstrate reduced peripheral RXR-α levels in human adolescents with ADHD, independent of medication status and symptom severity, extending preclinical retinoid signaling evidence.