Decreased levels of serum oxytocin in pediatric patients with Attention Deficit/Hyperactivity Disorder

Attention Deficit/Hyperactivity Disorder (ADHD) and autism spectrum disorder (ASD) are highly comorbid, and both disorders share executive function deficits. Accumulating evidence suggests that ASD patients have significantly lower peripheral oxytocin (OXT) levels compared with their normal counterparts, and that the repetitive behavior seen in ASD is related to abnormalities in the OXT system. In this study, we investigated whether serum levels of OXT are altered in pediatric patients with ADHD. We measured serum OXT levels: drug naive ADHD (n=23), medicated ADHD (n=13), and age- and sex- matched, neurotypical controls (n=22). Patients were evaluated using the ADHD-RS. Serum levels of OXT in total subjects with ADHD were significantly decreased compared with those of neurotypical controls, and serum levels of OXT in drug naive ADHD patients were significantly lower than those in medicated ADHD patients. Interestingly, there was a significant negative correlation between serum OXT levels and ADHD-RS total scores, as well as ADHD-RS inattentive scores in all ADHD patients. In conclusion, this study suggests that decreased levels of OXT may play a role in the pathophysiology of patients with ADHD and its inherent inattentiveness.