Co-occurring Anxiety in a Child With Autism and ADHD.

KM is an 11-year-old autistic boy followed by a developmental-behavioral pediatrician (DBP) practicing within a multidisciplinary autism center. He had been prescribed various attention-deficit hyperactivity disorder (ADHD) medications over the years, most recently dextroamphetamine-amphetamine extended-release capsule 10 mg daily.KM initially presented to the DBP for diagnostic confirmation of autism and ADHD at the age of 7 years. His school had conducted a detailed evaluation the year prior, indicating skills in the borderline range for cognitive, adaptive, and language functioning. Based on his developmental history, physical examination, review of school-based testing, and parent- and school-completed standardized questionnaires, he met Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for autism spectrum disorder and ADHD with combined presentation.When KM was between the ages of 8 and 10 years, he trialed several medications, including methylphenidate (which led to emotional lability), dextroamphetamine sulfate oral solution (which caused irritability), and clonidine (which led to destructive behavior). Notably, KM's parents were divorced and had differing opinions and experiences surrounding the efficacy and tolerability of his medications, which made medication trials more complex. He eventually was stabilized on extended-release dextroamphetamine-amphetamine at the age of 9 years, which both parents agreed was helpful for improving attention, despite the medication triggering a new self-injurious behavior of punching himself.At the age of 10 years, after 1 year of stability on dextroamphetamine-amphetamine extended-release capsule 10 mg daily, his parents chose not to refill the medication, to see whether it was still helpful for him. They observed that he seemed much "happier" with improved mood and decreased anxiety when dextroamphetamine-amphetamine was withheld; however, they did note worsened hyperactivity. A few weeks later, he began demonstrating increased symptoms of anxiety such as somatization and externalizing behaviors. This included frustration, aggression, and oppositionality, especially in anticipation of and/or when confronting anxious stimuli.His neuropsychologist and DBP collaborated to create a behavior monitoring plan to help his parents clarify and track his symptoms across households, with the goal of monitoring symptom severity and differentiating ADHD from anxiety-related symptoms. Because of this, his parents identified hyperactivity and impulsivity as KM's most problematic symptoms; therefore, dextroamphetamine-amphetamine extended-release 10 mg daily was restarted. Although this was effective for his hyperactivity, ongoing monitoring suggested that his anxiety symptoms continued to be clinically significant. The DBP consulted a psychiatrist who advised a trial of escitalopram in conjunction with dextroamphetamine-amphetamine. Several weeks after starting escitalopram 5 mg per day, KM exhibited reduced anxious thoughts and decreased aggression, but ongoing symptoms of inattention.Considering KM's complex presentation, how do we approach neuropsychological assessment, behavioral and therapeutic support, and psychopharmacology?