Processing speed as a marker to stimulant effect in clinical sample of children with high functioning autism spectrum disorder

Background: Patients with co-occurring Attention-Deficit/Hyperactivity Disorder (ADHD) and ASD might benefit from stimulants. There is a progressive increase in prescribing ADHD aimed medications for children diagnosed with Autism Spectrum Disorder (ASD), despite scarce knowledge and no distinct clinical guidelines for that matter. Aim: This study aims to analyze the effect of stimulant on processing speed performance and attention indices in children with ASD and ADHD. Methods: Forty children aged 6–18 years diagnosed with ASD who also met the criteria for ADHD were recruited. All children performed a computerized performance test for the assessment of cognitive attention performance three times: twice while they are drug naïve and once an hour after taking a single dose of 10 mg. methylphenidate (MPH). This performance was compared to a group of children diagnosed with ‘ADHD only’ without ASD. Results: A significant difference (p < 0.001) was found only in the parameter of measuring cognitive processing speed. This effect is significantly different from the response of the ‘ADHD only’ group. Conclusions: The reaction to MPH among ASD children is different than among ADHD children. In ASD, MPH significantly improved cognitive processing speed without changing other measured attention parameters. Improving processing speed, might improve every day functioning in children with ASD who also met the criteria for ADHD, in other means than expected. This unique response suggests new research targets for treatment with stimulants in ASD and ADHD children and its influence on cognitive parameters.