Methylphenidate-Induced Stuttering in a Patient With Autism Spectrum Disorder and Attention Deficit Hyperactivity Disorder: A Case Report.

Objective: Autism spectrum disorder (ASD) is a common neurodevelopmental condition marked by difficulties in social communication and interaction, along with the presence of repetitive behaviors or interests. ASD often co-occurs with attention deficit hyperactivity disorder (ADHD), and this comorbidity should be considered when developing a treatment plan. Methylphenidate (MPH) is a psychostimulant that is commonly used as the first-line treatment for ADHD. Despite its high effectiveness, adverse effects may occur especially in children with co-occurring ASD. Here, we aimed to present a case with ASD and ADHD who developed stuttering with the onset of MPH and discuss the literature.

Method and results: A 10.5-year-old boy with ASD was referred to our clinic due to symptoms of inattention, hyperactivity, and impulsivity. He was diagnosed with ADHD and prescribed OROS MPH at 18 mg/day, which was increased to 27 mg/day after 1 month. His ADHD symptoms moderately improved, but he began stuttering 1 week after the dosage increase. After discontinuing the medication, his speech fluency significantly improved. Three months later, OROS MPH was reintroduced at 27 mg/day, and the stuttering resumed. Consequently, MPH was discontinued, and his treatment is now being managed with atomoxetine.

Conclusions: Despite that the relationship between MPH and stuttering is not well-documented, it is important to recognize that side effects may arise when initiating treatment or increasing the dosage. Typically, quitting the medication is sufficient to alleviate these side effects. Further studies are needed to better understand the side effects and mechanisms of action associated with MPH.