Background: It is widely accepted that mental health problems are more common in adults with autism spectrum disorder (ASD) than in the general population. However, the estimated prevalence of mental health difficulties in adults with ASD varies widely between studies due to methodological differences and method of obtaining and assigning mental health diagnoses. In addition, the majority of research focuses on early adulthood or does not include individuals with co‐morbid intellectual disability.

Methods: The current study presents data from an ongoing longitudinal studying following a community sample of individuals with ASD from childhood to adulthood. Current mental health symptomology was collected from 80 participants (80% male; mean age = 33.8 years, range 26–44 years; 70% with co‐morbid ID), their family members and/or professional carers, using the Structured Clinical Interview for DSM‐5. The clinical information was reviewed by a panel, and consensus clinical diagnoses were assigned.

Results: Preliminary analyses suggest a high prevalence of co‐morbid mental health problems in adults with ASD. Information will be presented on rate and types of mental health problems, and childhood predictors of adult mental health problems will be explored.

Conclusions: The results will be discussed in relation to the need for interventions and supports for adults, along with the potential for targets for early intervention.