Research Snapshot: More people with autism have co-occurring mental illness than the general population

What you need to know

People with autism often have co-occurring mental illnesses. However, the reported prevalence rates seen in different studies have a wide range. Researchers conducted a study to look at the prevalence of co-occurring mental health conditions in people with autism. They found that co-occurring mental health conditions are highly prevalent in people with autism, and mostly significantly higher than in the general population. Prevalence ranged from 4% for schizophrenia spectrum disorders to 28% for attention-deficit hyperactivity disorder.

 

This Research Snapshot was written by Rossana Coriandoli and is based on the article, “Prevalence of co-occurring mental health diagnoses in the autism population: a systematic review and meta-analysis” which was published in Lancet Psychiatry in 2019. Read it below or download the PDF.

Research Snapshots are brief, clear language summaries of research articles, presented in a user-friendly format.

What is this research about?

People with autism often have co-occurring mental illnesses. Reports show as many as 70% of people with autism have at least one mental illness and almost half have more than one, but, overall, the reported prevalence seen in different studies have a wide range.

Researchers conducted a study to look at the prevalence of co-occurring mental health conditions in people with autism. They also tried to identify the factors that might account for these prevalence differences in previous studies.

What did the researchers do?

The researchers conducted a systematic review of published studies that looked at the prevalence of co-occurring mental health conditions in people with autism. They also analyzed the combined results in all the studies. They then determined the pooled estimates of the prevalence for different conditions and compared these with prevalence estimates in the general population.

The researchers also used a statistical method called random-effects meta-regression modelling to determine the degree of variability in the prevalence estimates.

What did the researchers find?

They found that co-occurring mental health conditions are highly prevalent in people with autism and mostly significantly higher than in the general population. The following eight co-occurring mental illnesses were the most common:

  • attention-deficit hyperactivity disorder 28%
  • anxiety disorders 20%
  • sleep–wake disorders 13%
  • disruptive, impulse-control, and conduct disorders 12%
  • depressive disorders 11%
  • obsessive-compulsive disorder 9%
  • bipolar disorders 5%
  • schizophrenia spectrum disorders 4%.

Estimates were higher in clinical studies than in population-based and registry-based studies. These estimates were mostly higher than were those in the general population.

The age, gender and intelligence make-up of the samples, the country of origin, and publication year of the study could explain some of the variability between studies. Substantial unexplained variability remained after accounting for these factors, which suggests there may be other contributing factors .

How can you use this research?

This research may be of use in the development of mental health promotion interventions for people with autism and their families, as well as for primary care professionals. It would also be of interest to autism researchers and other neurodevelopmental disabilities.

Limitations of the research

Various aspects of the study design resulted in limited ability to fully understand the context of co-occurring mental illness in people with autism. Therefore, more research is needed to confirm with certainty the prevalence of various mental health diagnoses in people with autism.

About the researchers

Meng-Chuan Lai,1,2,3,4,5 Caroline Kassee,1 Richard Besney,1 Sarah Bonato,1 Laura Hull,6 William Mandy,6 Peter Szatmari,1,2,3 Stephanie H Ameis1,2,3

  1. The Margaret and Wallace McCain Centre for Child, Youth & Family Mental Health and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON
  2. Centre for Brain and Mental Health and Department of Psychiatry, The Hospital for Sick Children, Toronto, ON
  3. Department of Psychiatry, Faculty of Medicine, University of Toronto, Toronto, ON
  4. Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK
  5. Department of Psychiatry, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
  6. Research Department of Clinical, Educational and Health Psychology, University College London, London, United Kingdom

Keywords 

autism, mental illness, attention-deficit hyperactivity disorder, anxiety, sleep, wake, disruptive, impulse, conduct, depressive, obsessive-compulsive, bipolar disorder, schizophrenia

This Research Snapshot is based on the article, “Prevalence of co-occurring mental health diagnoses in the autism population: a systematic review and meta-analysis” which was published in Lancet Psychiatry in 2019. https://dx.doi.org/10.1016%2Fj.jaac.2020.05.009