Schizophrenia in autistic people with intellectual disabilities: Symptom manifestations and identification.

Bakken, T. L., Kildahl, A. N., Ludvigsen, L. B., Bjørgen, T. G., Dalhaug, C., Hellerud, J. M. A., Hove, O., Solheim-Inderberg, A. M., Karlsen, K., & Helverschou, S. B. (2023). Schizophrenia in autistic people with intellectual disabilities: Symptom manifestations and identification. Journal of applied research in intellectual disabilities : JARID, 36(5), 1076–1091. https://doi.org/10.1111/jar.13127

The article by Bakken et al., published just last year, is really helpful – albeit heavy – in the subspecialized field of intellectual disabilities and autism. It starts by acknowledging that diagnosis is difficult. There are patient factors, such as the inability to easily communicate what is going on inside, or in the way that others without neurodiversity might. The authors also highlight the significant difficulty in differentiating schizophrenia or psychosis from autism. Delusions, commonly described as fixed, false beliefs (usually strange or bizarre), could be argued as autistic misinterpretation, or vice versa. People with ASD also have a peculiar way of talking sometimes, which could also be misinterpreted.

Unfortunately, the distress of psychosis and schizophrenia in those with these conditions is severe, and heartbreaking for the carers, loved ones, and even doctors like myself. Often, neurodivergent people have difficulty distinguishing between common and uncommon thoughts, and therefore won't tell others about what’s going on.

The article goes on to talk about assessing for these conditions using a number of sources. Apart from seeing the patient, it's important to review past medical records, caregiver information, professional tools and scales, and observational strategies. Adequate diagnosis is essential to provide timely and appropriate treatment. Unfortunately, current literature is minimal, usually involving small samples and lacking comparison groups.

This study by the wonderfully intelligent Bakken et al. found individuals with autism and intellectual disability aged over 14 who were referred to any mental health center. They found 183 participants—a decent number—and made a few comparison groups, including differentiating by gender and co-existing conditions. The team then reviewed the symptoms and diagnostic foundations—either through checklists, observations, or combinations.

And what did they find? All 26 patients who had schizophrenia experienced a decline in functioning for at least 6 months! Common symptoms were restlessness, anxiety, concentration problems, low mood, and irritability. Core symptoms of schizophrenia also occurred. So, what does that mean? Perhaps taking the time and effort to go back to basics is worth it in getting the diagnosis right. Co-occurring anxiety and depression were common. Only the PAC Psychosis Scale really distinguished those with psychosis from those with other conditions, because the scale looks at the core symptoms of schizophrenia.

Another takeaway, however, was that even though core symptoms are similar, there is a wide variety of non-core symptoms, which means adapting the diagnosis and treatment is important. Many of those diagnosed with psychosis were also admitted to the hospital, which allows for much more aggressive observation, also helping with the veracity of the diagnosis. Maybe this should argue for a specialized inpatient unit for those with disabilities—an argument I have often thought would have some merit!

Another feature of the research was that there was greater difficulty in diagnosing psychosis in the more intellectually disabled population, which makes sense as core symptoms depend significantly on language and adaptive skills.

Overall, psychosis can and should be diagnosed in neurodivergent, autistic teenagers and adults with intellectual disability. There are screening tools, but a detailed, comprehensive, and multimodal approach seems to be best.