Abstract
BackgroundClinical studies found that medication for attention-deficit/hyperactivity disorder (ADHD) is effective in coexisting autism spectrum disorder (ASD), but current research is based on small clinical studies mainly performed on children or adolescents. We here use register data to examine if individuals with ADHD and coexisting ASD present differences in the prescribing patterns of ADHD medication when compared to individuals with pure ADHD.MethodsData with information on filled prescriptions and diagnoses was retrieved from the Swedish Prescribed Drug Register and the National Patient Register. We identified 34,374 individuals with pure ADHD and 5012 individuals with ADHD and coexisting ASD, aged between 3 and 80 years. The first treatment episode with ADHD medications (≥ 2 filled prescriptions within 90 days) and daily doses of methylphenidate during a 3-year period was measured. Odds ratios (ORs) were calculated for the likelihood of being prescribed ADHD medication in individuals with and without ASD and Wilcoxon rank-sum test was used to compare group differences in dose per day.ResultsIndividuals with ADHD and coexisting ASD were less likely to start continuous treatment with ADHD medication (ADHD 80.5%; ADHD with ASD 76.2%; OR, 0.80; 95% confidence interval, 0.75-0.86), were less likely to be prescribed methylphenidate, and were more commonly prescribed second line treatments such as dexamphetamine, amphetamine, or modafinil. No group difference was observed for atomoxetine. In adults with ADHD and coexisting ASD, methylphenidate was prescribed in lower daily doses over three years as compared to individuals with pure ADHD.ConclusionsThe findings indicate that there are differences in the medical treatment of individuals with or without ASD. If these differences are due to different medication responses in ASD or due to other factors such as clinicians’ perceptions of medication effects in patients with ASD, needs to be further studied.
Highlights
Clinical studies found that medication for attention-deficit/hyperactivity disorder (ADHD) is effective in coexisting autism spectrum disorder (ASD), but current research is based on small clinical studies mainly performed on children or adolescents
If these differences are due to different medication responses in ASD or due to other factors such as clinicians’ perceptions of medication effects in patients with ASD, needs to be further studied
Registers The cohort was established by linking health care registers including the National Patient Register (NPR), with psychiatric diagnoses and dates with codes in accordance with International classification of diseases (ICD) from 1973 and 2001; the Total Population Register with information on year of birth on all residents in Sweden; and the Swedish Prescribed Drug Register (PDR), with information on all filled prescriptions from pharmacies in Sweden from July 1, 2005
Summary
Clinical studies found that medication for attention-deficit/hyperactivity disorder (ADHD) is effective in coexisting autism spectrum disorder (ASD), but current research is based on small clinical studies mainly performed on children or adolescents. Meta-analyses on available randomized clinical trials (RCTs) show that ADHD medications, e.g., methylphenidate [13], and atomoxetine [14] improve ADHD symptoms in children and adolescents with ASD. Some studies showed that ADHD medications were less tolerated in children and adolescents with ASD [13], and individuals with ASD presented higher discontinuation rates due to side effects such as irritability [16]. Clinical experience includes case reports about need for higher, as well as lower, doses of ADHD medication in patients with coexisting ADHD and ASD
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