Objectives: The aim of this study was to assess effectiveness and tolerability of Clozapine in the treatment of aggression in youth with Neurodevelopmental Disorders. Methods: Patients were consecutively admitted at our third-level university hospital with nationwide catchment from June 2018 to October 2022, and followed up to July 2023. Eligibility criteria were as follows: (1) Autism Spectrum Disorder (ASD) and/or Intellectual Disability/Borderline Cognitive Functioning, (2) behavioral dyscontrol with physical aggression; (3) age range between 8 and 18 years; (4) clinical indication for Clozapine treatment after at least two failed trials with other Second-Generation Antipsychotics (SGAs); (5) availability of an at least 6-month-long follow-up. To evaluate the response to Clozapine, we used the Clinical Global Impressions (CGI) rating scales (Clinical Global Impressions-Severity [CGI-S] and Clinical Global Impressions-Improvement [CGI-I]), the Children's Global Assessment Scale (CGAS), and the Aberrant Behavior Checklist (ABC). Results: Twenty-six children and adolescents (21 boys, age 13.47 ± 2.05 years, follow-up duration 9.77 ± 3.50 months) were included in the analysis. Clinical severity (CGI-S) and functional impairment (Clinical Global Assessment Scale) significantly improved, as well as the ABC Total Score and the scores in several subscales. Sixteen patients (61.54%) were responders (CGI-I ≤2), and 13 (50.00%) displayed remission of aberrant behaviors (ΔABC-Total >35), while response/remission condition was not affected by add-on medications and psychotherapy. Most frequent side effects were increased appetite (50.00%), sialorrhea (38.46%), and increased repetitive behaviors (26.92%). Two patients presented epileptic seizures, while no patients presented leucopoenia. Conclusions: Our results suggest that Clozapine may be helpful in ameliorating treatment-resistant aggression in youth with neurodevelopmental conditions. Possible pharmacological strategies for the management of most frequent side effects are also suggested.
Keywords: Clozapine; adolescents; aggression; autism spectrum disorder; children; intellectual disability.