Prevalence of Asperger syndrome among patients of an Early Intervention in Psychosis team.

Background: There is a lack of systematic studies into comorbidity of Asperger syndrome and psychosis.

Aim: To determine the prevalence of Asperger syndrome among patients of an early intervention in psychosis service.

Methods: This study was a cross-sectional survey consisting of three phases: screening, case note review and diagnostic interviews. All patients on caseload (n = 197) were screened using the Autism Spectrum Disorder in Adults Screening Questionnaire. The case notes of patients screened positive were then reviewed for information relevant to Asperger syndrome. Those suspected of having Asperger syndrome were invited for a diagnostic interview.

Results: Thirty patients were screened positive. Three of them already had a diagnosis of Asperger syndrome made by child and adolescent mental health services. After case note review, 13 patients were invited to interview. Four did not take part, so nine were interviewed. At interview, four were diagnosed with Asperger syndrome. In total, seven patients had Asperger syndrome. Thus, the prevalence rate in this population is at least 3.6%.

Conclusions: The results suggest that the prevalence of Asperger syndrome in first-episode psychosis is considerably higher than that in the general population. Clinicians working in early intervention teams need to be alert to the possibility of Asperger syndrome when assessing patients.