Antipsychotic medication in people with intellectual disability and schizophrenia: A 25-year updated systematic review and cross-sectional study.

OBJECTIVES To determine the efficacy and safety of antipsychotic medication for treating individuals with a dual diagnosis of intellectual disability (ID) and schizophrenia. METHODS We systematically reviewed the literature to explore the risks and benefits of antipsychotics for schizophrenia in ID. In addition, a cross-sectional retrospective study on the tolerance profiles of a representative ID and schizophrenia cohort was conducted. RESULTS From the systematic search, we retained 18 articles detailing information on 24 cases. In almost all cases, the antipsychotic improved psychotic symptoms (e.g., hallucinations, delusions, disorganization). Negative manifestations were also improved (blunted affects, amotivation, poor rapport), as were challenging behaviors in a few cases. The most commonly reported side effects were neurological (extra-pyramidal, movement disorder, epilepsy) and metabolic manifestations. In the retrospective cross-sectional study, we reported data on 112 participants with comorbid ID and schizophrenia. In all, 103 participants were antipsychotic-treated, of which 39% were on antipsychotic monotherapy. Of these, 35% were in the obesity range, 25% in the hyperglycemic range, and 25% in the dyslipidemia range. The body mass index did not differ between the groups. CONCLUSIONS This study provides an initial evidence base underpinning the efficacy of antipsychotic drugs on schizophrenia in the ID population. Nevertheless, there may be an increased risk of metabolic side effects, hence, close monitoring of blood glucose, lipids, and weight should be implemented when prescribing antipsychotics to this population.