Autism in adult psychiatry outpatients - prevalence, comorbidity, suicidality and cognition

Abstract: Background: Autism Spectrum Disorder (ASD), one of the Early Symptomatic Syndromes Eliciting Neurodevelopmental Clinical Examinations (ESSENCE), is a neurodevelopmental disorder (NDD) characterised by a pattern of deficits in reciprocal social communication and social interaction, and restricted and/or repetitive behaviours (including sensory abnormalities). Under its current DSM-5 definition, ASD occurs worldwide in 1-1.5% of the general population but is more prevalent in clinical populations. The prevalence of ASD in adult psychiatric outpatient services is not known, and adult psychiatric outpatients with ASD are often not examined “holistically”. Aims: Examine prevalence of ASD in adult outpatient psychiatry, psychiatric, cognitive and sociodemographic profiles, functional level, suicidality and non-suicidal self-injury (NSSI). Methods: Studies I, II and III examined newly referred psychiatric outpatients (N = 90) at a psychiatric outpatient clinic in Helsingborg, Sweden during 2019 and 2020. Patients were screened with the Ritvo Autism Asperger Diagnostic Scale – Revised (RAADS-R) or the abbreviated RAADS-14 Screen, and patients with screening results indicating possible ASD were offered to participate in in-depth clinical assessments by experienced clinicians using well-validated psychometric instruments. In Study IV neuropsychological test results were analysed in outpatients (N = 30) who had received clinical diagnoses of ASD at an NDD assessment unit. Results: ASD was diagnosed in 18.9% of newly referred outpatients, with an additional 5.7% showing “subthreshold” symptoms of ASD. Participants with ASD had more psychiatric comorbidity, more NDDs, more anxiety disorders and lower functional level compared to participants without ASD. No differences were found between participants with and without ASD in sociodemographic characteristics. Suicidal thoughts and behaviour, and NSSI, were common among participants with ASD; similar to what has previously been reported among psychiatric outpatients. Substantial deficits in functional level were found, regardless of Intelligence Quotient (IQ) level. Working memory and processing speed explained more than one fifth of the variance in functional level. Conclusions: In summary, the results of this thesis suggest that adult psychiatric services need a substantial increase in knowledge about ASD, and to adjust and adapt protocols and routines to become more “autism-friendly”.