The 'lost generation' in adult psychiatry: psychiatric, neurodevelopmental and sociodemographic characteristics of psychiatric patients with autism unrecognised in childhood

BackgroundPatients with 'underlying' autism spectrum disorder (ASD) constitute a significant minority in adult out-patient psychiatry. Diagnoses of previously unrecognised ASD are increasing in adults. Characteristics of patients with autism within adult out-patient psychiatry have not been sufficiently explored, and there have not been any systematic comparisons of characteristics between patients with and those without autism within adult out-patient psychiatric populations. AimsTo examine psychiatrically relevant characteristics in autistic adult psychiatric out-patients, and to compare the characteristics with non-autistic adult psychiatric out-patients. MethodWe assessed 90 patients who were referred to a Swedish psychiatric out-patient clinic and screened for ASD during 2019-2020. Sixty-three patients met the DSM-5 criteria for ASD or 'subthreshold' ASD. The 27 who did not meet the criteria for ASD were used as a comparison group. Assessments were made with structured and well-validated instruments, including parent ratings of developmental history. ResultsNo differences were found between the groups regarding self-reported sociodemographic variables. The ASD group showed a higher number of co-occurring psychiatric disorders than the non-ASD group (t((88)) = 5.17, 95% CI 1.29-2.91, d = 1.19). Functional level was lower in the ASD group (t((88)) = -2.66, 95% CI -9.46 to -1.27, d = -0.73), and was predicted by the number of co-occurring psychiatric disorders. ConclusionsThe results underscore the need for thorough assessment of psychiatric disorders in autistic patients in adult psychiatric services. ASD should be considered as a possible 'underlying' condition in adult psychiatry, and there is no easy way of ruling out ASD in this population.

Automated summary

This study aims to investigate the characteristics of autism spectrum disorder (ASD) in adult psychiatric outpatients and compare them with non-ASD patients. The results showed that the ASD group had a higher number of co-occurring psychiatric disorders and lower functional level compared to the non-ASD group. This study emphasizes the importance of comprehensive assessment of psychiatric disorders in ASD patients in adult psychiatric services.