Statistically significant association between cytokines and ADHD symptoms. Increases in interleukins IL-16 and IL-13, were positively associated with hyperactivity and inattention, respectively; decrease in IL-2 was associated with opposition ratings in ADHD. In the CPT, IL-16 related to motor measures and errors of commission, while IL-13 was associated with errors of omission. Increased RT variability correlated with lower TNF-α, and higher IFN-γ levels. This evidence concerns the gene IL2 and attention deficit-hyperactivity disorder.