Psychiatric and physical comorbidity in adults with autism spectr.pdf (1.95 MB)
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Psychiatric and physical comorbidity in adults with autism spectrum disorder

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posted on 22.11.2019, 18:29 authored by Linda O'Rourke

Autism spectrum disorder (ASD) is a highly impairing neurodevelopmental condition, manifesting in childhood and continuing into adult life. Comorbid psychiatric and physical illness lends considerable increased mortality to the condition. An increased awareness of comorbid conditions in adults with normal IQ ASD could improve diagnostic formulation, facilitate targeted treatments and improve psychosocial outcomes.

This study examines the prevalence of comorbid psychiatric and physical illness in 413 adults with normal IQ ASD, attending a tertiary referral neurodevelopmental clinic in South London, to determine if rates of comorbid illness would be greater than rates reported in the general population.

This study noted autism spectrum disorder in 70% of participants, with a male-to-female ratio of 2.8:1. Milder forms of ASD were recorded for 88%. Participants with autism spectrum disorder were more likely to be single, unemployed and living in the company of others. Seventy-six percent suffered from a comorbid Axis I illness and 2% suffered from a comorbid Axis II condition. Anxiety spectrum disorders were the most common comorbid psychiatric illness, followed by attention deficit hyperactivity disorder, mood disorders and deliberate self-harm. Psychosis, substance-use disorder, eating disorder and tic disorder were rarely diagnosed. Participants with Asperger’s syndrome were statistically more likely to be diagnosed with a comorbid psychiatric illness, most commonly obsessive compulsive disorder. Eighty-four percent of participants had a history of physical illness, most frequently asthma followed by head injury. Sleep difficulties and eating disturbance were notably high at 42% and 25% respectively.

Adults with normal IQ autism spectrum disorder suffer higher rates of physical and psychiatric morbidity, display a poorer ability to engage with treatment and have a lower chance of recovery compared to the general population. Increased awareness and a high degree of diagnostic skill to identify those with the disorder should be promoted among physicians and psychiatrists.


First Supervisor

Professor Kieran Murphy

Second Supervisor

Professor Declan Murphy


A thesis submitted for the degree of Doctor of Medicine from the Royal College of Surgeons in Ireland in 2016.

Published Citation

O'Rourke L. Psychiatric and physical comorbidity in adults with autism spectrum disorder [MD Thesis]. Dublin: Royal College of Surgeons in Ireland; 2016.

Degree Name

Doctor of Medicine (MD)

Date of award


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