We have identified more than 60* research papers on risperidone as an intervention for autistic people published in English-language, peer-reviewed journals.
These papers included more than 1,000 individuals aged from 3 to 48 years old, although the majority were primary school children or adolescents. These individuals included people with autistic disorder, Asperger syndrome and pervasive developmental disorder - not otherwise specified.
The majority of studies were carried out by single research teams on single sites but some of the larger studies were carried out by several researchers on several sites. In the case of the series of studies carried out by the Research Units on Pediatric Psychopharmacology (RUPP) Autism Network we have identified more than 10 different papers. Some of these papers set out the rationale for the studies and explained the methodologies that would be used. Some of these papers reported on different parts of the studies (which included several controlled trials and several open trials). Some of the papers investigated the effects of risperidone on specific issues (such as adaptive behaviours, social communication and social interaction or repetitive and restricted behaviours). Some of the papers evaluated whether risperidone caused specific adverse effects (such as weight gain, somnolence and raised serum prolactin levels).
The length of treatment described in the papers we identified varied between six weeks and three years, although in most cases the treatment lasted between six to eight weeks. The dosage of risperidone varied from 0.75 mg per day to 3.5 mg per day, with younger children receiving smaller doses than adolescents and adults. In most cases, risperidone was started at a low dose and gradually increased to a higher maximum dose.
Approximately half of the studies used a group design (usually comparing a group of people receiving risperidone to a different group receiving a placebo). Approximately half of the studies used singe case designs (usually in the form of an open trial of risperidone within a single group).
A minority of the group studies compared risperidone with other antipsychotics (such as aripiprazole or haloperidol) or with other types of medication (such as buspirone or memantine). One of the studies compared low dose risperidone against high dose risperidone. Two of the studies compared risperidone combined with a parent training programme against risperidone alone.
*Please note: we have not included studies with fewer than three autistic participants and we have not included studies which combined risperidone with one or more other substances (including other medications or dietary supplements). We have also not included any of the papers from the Research Units on Paediatric Psychopharmacology Autism Network studies where these did not measure the efficacy or otherwise of risperidone.