Psychopharmacologic Intervention for Adults with Autism Spectrum Disorder: A Systematic Literature Review

Background:  The increased recognition of psychiatric and behavioural disorder in adults with autism spectrum disorder (ASD) has been associated with more frequent use of psychopharmacologic intervention in this population. Indeed, evidence from recent research indicates that up to 81% of adults with ASD take at least one psychotropic medication, with a high proportion of these individuals taking three or more medications. The primary indicator of psychotropic medication use in this population is behavioural disturbance, often in the absence of a diagnosed psychiatric disorder. However, limited evidence supports the effectiveness of these interventions for adults with ASD.

Objectives: The objective of this review was to synthesize the literature that has explored the efficacy of psychotropic medication in reducing behavioural disturbance in adults with ASD. A secondary objective was to describe the strength of the evidence for psychopharmacologic intervention in this population.

Methods:  An electronic database search of PubMed was conducted in January 2015. The literature search yielded 366 articles. Articles were included in the review if they met the following criteria: (1) the article described at least one adult (>18 years) with (a) a confirmed diagnosis of ASD, Autistic Disorder, Asperger’s Disorder or Pervasive Developmental Disorder-Not Otherwise Specified, or (b) reported clinical features typical of ASD, (2) the article described at least one outcome measures, and (3) the article was published in English in a peer-reviewed journal.

Results:  Forty-three studies were included in the analysis. The results indicated that Only two psychotropic medications, risperidone and fluoxetine, met Reichow et al.’s (2008) criteria for promising evidence-based interventions for reducing irritability and repetitive behaviour associated with ASD in adults. Evidence from two placebo-controlled trials, in addition to one case series, indicated that fluoxetine results in a reduction in repetitive and obsessive-compulsive behaviour in adults with ASD. Similarly, the results of two placebo-controlled trials, in addition to two small open-label trials, indicate that risperidone may be effective in reducing repetitive, aggressive and self-injurious behaviour in adults in this population. The efficacy of all remaining agents has been investigated in case studies or small open label trials, so the evidence base for these interventions cannot be established.

Conclusions: Despite high rates pf psychopharmacologic intervention in ASD, there are few psychotropic medications which can be considered to have an established evidence base. Given the lack of evidence-base for psychopharmacologic intervention for adults with ASD, there is an imperative to conduct placebo-controlled trials that measure the safety, efficacy and tolerability these interventions when used to treat features associated with ASD. It is also necessary to establish clinical guidelines governing the use of psychopharmacology in this population.