Title : Unmasking severe autism spectrum disorder in a preschool child initially diagnosed with ADHD

Background: Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) frequently coexist, yet recognizing both conditions in preschool children is challenging because social-communication deficits, language delay, inattention, hyperactivity, and emotional dysregulation overlap. Misattributing autistic features to ADHD may delay appropriate developmental intervention. We report a preschool child initially diagnosed with ADHD who was subsequently identified as having severe ASD with comorbid combined-type ADHD, highlighting the importance of comprehensive developmental assessment.

Case Presentation: A 3-year-11-month-old boy was referred to a tertiary pediatric center for behavioral problems and developmental delay. Language delay emerged at 2 years of age, accompanied by minimal eye contact and limited reciprocal communication. This was followed by frequent tantrums, screaming, impulsive aggression, and marked hyperactivity. He exhibited characteristic autistic behaviors, including toe walking, hand flapping, repetitive spinning of objects and toy arrangement, insistence on sameness, and marked distress when objects were rearranged. Functional communication was severely impaired, with a vocabulary of only three words. Developmental assessment demonstrated delays in language and personal-social domains, whereas gross and fine motor skills were preserved. Hearing assessment was normal.

Diagnostic Assessment and Management: Comprehensive clinical assessment using DSM-5 criteria supported ASD, while the Childhood Autism Rating Scale (CARS) score was 57, consistent with severe ASD. Concurrent assessment identified seven inattentive and six hyperactive/impulsive symptoms, with an Abbreviated Conners Rating Scale score of 28, supporting combined-type ADHD. Together, these findings supported a diagnosis of severe ASD with comorbid combined-type ADHD rather than isolated ADHD and informed targeted treatment planning. Management emphasized multidisciplinary intervention, including speech and language therapy, occupational therapy with sensory integration, behavioral intervention, structured home-based stimulation, parent education, and psychiatric follow-up. Risperidone was initiated at 0.125 mg twice daily and gradually titrated according to behavioral response; fluoxetine was subsequently added. After approximately three months of multidisciplinary intervention, the child demonstrated improved emotional regulation, greater ability to follow one-step commands, increased use of gestures for communication, improved feeding independence, and reduced physical aggression.

Conclusion: In preschool children presenting with hyperactivity and behavioral problems, ADHD should not end the diagnostic assessment. Persistent social-communication deficits and restricted, repetitive behaviors warrant evaluation for ASD to enable early, individualized multidisciplinary intervention.

Rufaida Mudrika, MD, is a pediatric resident at the Faculty of Medicine, Universitas Indonesia, and Dr. Cipto Mangunkusumo Na@onal Referral Hospital, Jakarta, Indonesia. Her academic interests include pediatric neurodevelopment, behavioral pediatrics, clinical research, and evidence-based pediatric care. She is ac@vely involved in clinical prac@ce, research, teaching, and scien@fic presenta@ons in pediatrics.