59.1 ADHD IN AUTISM SPECTRUM DISORDER

Abstract

The objective of this presentation is to assess the evidence for the comorbidity, impact, and treatment of ADHD in populations with autism spectrum disorder (ASD). A database search of peer-reviewed literature was conducted. Selected studies examining the prevalence, characteristics, and impact of ASD in ADHD were reviewed. Controlled trials published in English with sample sizes ≥10 examining the safety and efficacy of anti-ADHD medication in populations with ASD were analyzed. Data were extracted on relevant variables of study design, demographics, associated psychopathology, medication dose, efficacy, and tolerability. Because of the previous prohibition of the diagnosis of ASD and ADHD, most studies are contemporary. Up to three-quarters of young people with ASD have ADHD. Conversely, ASD traits are noted in up to 30% of youth with ADHD and are associated with poorer socialization and functioning. Nine controlled trials met the criteria: 5 with methylphenidate, 3 with atomoxetine, and 1 with guanfacine. Sample sizes ranged from 10 to 128, with a total (N) of 430 children. In all of the trials, the treatment response was significantly superior to placebo. However, almost all trials assessed only hyperactivity, and most included only participants with intellectual disability with high levels of irritability. While the response on hyperactivity for methylphenidate and atomoxetine was less than that observed in the neurotypical population, the response for guanfacine surpassed the results observed in neurotypical populations. More traditional response rates were noted in patients with normal IQ. Treatment-emergent mood effects were associated with methylphenidate and guanfacine treatments. Worse treatment outcomes were associated with lower intellectual capability compared to higher IQs, for both efficacy and adverse outcomes. There is an important bidirectional overlap between ADHD and ASD. Individuals with both disorders manifest more functional impairment necessitating treatment. There is a scarcity of controlled trials examining ADHD treatments in populations with ASD, particularly in intellectually capable individuals with ASD and in adults. Response to ADHD medications in ASD appears similar to neurotypical ADHD samples with higher IQs; however, it was adversely moderated by the presence of intellectual disability and mood lability.