Autism Spectrum Disorder May Be Highly Prevalent in People with Functional Neurological Disorders

Recent observations suggest that autism spectrum disorder (ASD) co-occurs in people with a functional neurological disorder (FND), but little systematic data are available on the relationship between FND and autism. The study aimed to assess the self-reported autistic traits via a standardized questionnaire and the prevalence of previously diagnosed ASD among people with FND and their 1st-degree relatives. We performed a survey of members of the patient organization FNDHope, using a self-completed questionnaire for screening for autistic traits and ASD: the adult autism subthreshold spectrum (AdAS spectrum). There were 344 respondents diagnosed with FND with a mean age of 39.8 +/- 11.6 years (female sex 90%). Eight per cent of respondents volunteered a previous diagnosis of ASD, and 24% reported a 1st-degree relative with a formal diagnosis of ASD, mostly their children. We found that 69% of respondents had scores in the AdAS spectrum indicating a clinically significant ASD and 21% indicating autistic traits. Further studies are needed to provide more evidence regarding the prevalence of ASD in people with FND and how this may influence the aetiology, treatment selection and prognosis.