Clozapine for persons with neurodevelopmental disorders: a systematic review and expert recommendations for clinical practice

We aimed to synthesize the information on the risks and benefits of clozapine prescription for resistant challenging behavior in persons with neurodevelopmental disorders. Articles were identified with MEDLINE, Web of Sciences, and PsycINFO search from inception through January 2024. The review was restricted to persons with intellectual disability (ID) and/or autism spectrum disorder (ASD) without comorbid psychotic or affective disorder. Data were synthesized narratively. We identified 24 articles (13 case reports, eight chart studies, two controlled studies, one pharmaco-epidemiological study) including 296 patients with ID (<i>n</i> = 222) or ASD (<i>n</i> = 74) (10% aged ≤ 18 years). After clozapine initiation, a decreased frequency of challenging behavior persisting over time was reported in most participants included in clinical studies, and a significant reduction in the number of admissions in the population-based two-year mirror-image study. Adverse drug reactions were those commonly observed with clozapine, i.e. constipation, sedation, and weight gain. Since only four participants were included in the controlled studies, the benefits of clozapine in neurodevelopmental disorders are supported by a body of evidence exclusively drawn from observational studies. Further studies are required to clarify the indications of clozapine with respect to the unmet need induced by resistant challenging behavior. PROSPERO database registration number CRD42024522343