Abstract
Autism Spectrum Disorder (ASD) and attention deficit hyperactivity disorder (ADHD) comorbidity is common in clinical practice and it seems to be related to shared etiological mechanisms and genetic susceptibility. Moreover, occurrence of psychosis can further complicate these complex clinical pictures. Here, we discuss the case of a nine-years-old boy presenting with an episode of abnormal sustained posture of the upper limbs, resembling dystonia, at the age of 3. At this time, auditory and visual hallucinations, as well as obsessive thoughts and attentional lability were also present and a diagnosis of "Early onset psychosis" was initially made. Due to the worsening of clinical picture, several hospitalizations were necessary and pharmacological treatment with carbamazepine, risperidone and aripiprazole was carried out. Extensive clinic evaluation revealed a past medical and personal history of toe walking, weak social skills and stereotyped behavior observed and ADOS-2 Module 2 administration revealed severe Autism scores. Moreover, signs of attention and hyperactivity were consistent with ADHD diagnosis. This work highlights the importance of a complete diagnostic assessment in patients with complex presentation, suggesting the possible overlap diagnosis of ADHD and Autism even in presence of psychotic-like symptoms.