Autistic spectrum disorders and schizophrenia in the adult psychiatric setting: diagnosis and comorbidity

Abstract

Background: The relationship between Autism Spectrum Disorders (ASDs) and schizophrenia is currently unclear. We aimed to (a) assess psychotic symptoms in a consecutive series of adult patients with ASDs, (b) evaluate the comorbidity diagnosed to account for the concurrent psychotic symptoms in patients with ASDs, and (c) compare the clinical features between the patients with schizophrenia and patients with comorbid schizophrenia and ASDs.

Subjects and methods: We included patients with ASD that were seen in adult psychiatric clinical settings during a 15-year period. The sample was further grouped according to the existence of a comorbid diagnosis of schizophrenia. Clinical and epidemiological features were assesed in in the whole sample, and further compared between the two groups.

Results: We identified 26 patients with first-time diagnosed ASDs. Among the 22 cases who manifested psychotic symptoms (84.6%), 16 had a concurrent diagnosis of schizophrenia (72.73%) and 6 of mood disorders (27.27%). Compared with patients with schizophrenia patients with comorbid ASDs and schizophrenia were more often men, of younger age, and more frequently developed motor side effects to antipsychotics.

Conclusions: Adult psychiatric service users with ASDs are often misdiagnosed. This could be in part due to the fact that adult psychiatrists are not familiar with the diagnosis of ASDs. The high prevalence of psychotic symptoms in this sample is likely to depend on the specific setting of the study, i.e., that people with more severe forms of ASD than those typically followed-up in the national health service were reaching our public inpatient and private outpatient services. The high comorbidity rate between ASDs and schizophrenia could be related to shared neurobiology, but also to arbitrary restrictions imposed by current diagnostic systems.