“…In particular: (a) psychostimulants have been proven effective in reducing the hyperactivity and impulsivity, present in up to a third of ASD cases (Simonoff et al, 2008;Harfterkamp et al, 2012). Their efficacy is somewhat lower compared to effects in children with "pure" ADHD, while side effects (i.e., irritability, lethargy, tics, sadness, and social withdrawal) tend to be more frequent and severe in autistic children with comorbid ADHD (Research Units on Paediatric Psychopharmacology Autism Network, 2005; Simonoff et al, 2013); (b) SGAs, particularly risperidone and aripiprazole, have been shown to control irritability, agitation, compulsions and aggressiveness, with evidence of maintained efficacy for up to 6 months of treatment in the majority of patients (Marcus et al, 2009;Zuddas et al, 2011); (c) SSRIs display some efficacy on anxiety and repetitive behaviours in adults, but not in children and adolescents with autism (Williams et al, 2010). This lack of efficacy in the paediatric ASD population is likely related to age-specific differences in underlying neurobiological mechanisms, to target symptoms (autistic individuals report anxiety as distressing and stereotypic behaviours as relaxing), and to the use of assessment tools and outcome measures that have been validated only in individuals without ASD (Reiersen and Handen, 2011).…”