We have identified 18 articles on the use of methylphenidate as a treatment for people on the autism spectrum in peer-reviewed journals published in English.
Four of the articles (Jahromi et al, 2009; Posey et al, 2007; Research Units on Pediatric Psychopharmacology Autism Network, 2005; Scahill et al) reported on the same clinical trial.
These studies we identified included more than 600 individuals on the autism spectrum aged from three years old to 18 years old, although the bulk of studies looked at primary school children and adolescents. Individuals with specific diagnoses included people with autistic disorder, Asperger syndrome or pervasive developmental disorder - not otherwise specified. Most of the participants in these studies were also diagnosed with attention deficit hyperactivity disorder (ADHD).
The length of intervention varied between a single, one-off dose to multiple doses delivered over three years. However, in most cases, the intervention lasted between four to six weeks. The dosage of methylphenidate varied from 0.21 mg per kg body with per day to 1.5 mg per kg body weight per day. Younger children received smaller doses than adolescents and adults. In most cases, the medication was started at a low dose and gradually increased to a higher maximum dose.
10 of the studies used a group design, usually comparing a specific dose of methylphenidate with a placebo and/or with a different dosage of methylphenidate. Nine of these group studies used a crossover design in which the participants received first one treatment and then another. One of the studies used a parallel group design in which different groups of participants received different dosages of methylphenidate. Eight of the studies used a single case design in which the participants only received methylphenidate or another stimulant but nothing else.