Autism Spectrum Disorder and Co-Occurring Psychiatric Conditions: A Conceptual Framework

There is strong evidence to suggest that individuals with autism spectrum disorder (ASD) are at heightened risk for developing co-occurring psychiatric conditions. However, the reasons behind this increased risk remain unclear. This chapter describes multiple conceptual models of the reasons for comorbidity and appraises the strength for each in relation to currently available evidence. The first section considers the evidence to suggest the reported increase in prevalence can be explained by purely artefactual factors (e.g., issues in sample acquisition or symptom measurement) and concludes this is unlikely as a complete explanation. The second section discusses more theoretical models, and how these could manifest in autistic individuals (e.g., increased prevalence or potency of established risk factors, and the role of ASD-specific risk factors). There is evidence to support multiple mechanisms playing a role in explaining the increased prevalence of psychiatric conditions, and these mechanisms are unlikely to be mutually exclusive. As the current literature is limited, priority areas for future research are suggested, including the need for accurate measurement of predictors and outcomes, more sensitive research designs, and the inclusion of underrepresented groups.