NEUROPSYCHIATRY: PART 2
The Centers for Disease Control and Prevention estimates that autism affects 1 in every 59 children in the US.1 While the core features of autism impair functioning, a significant source of further impairment is comorbid psychiatric disorders. People with autism spectrum disorder (ASD) are more likely than the general population to have comorbid psychiatric disorders. Although prevalence rates vary widely, converging evidence suggests that anxiety disorders and ADHD are most prevalent.
Numerous factors contribute to the increased risk for comorbid psychiatric disorders. People with autism are at higher risk of being bullied and are more likely to experience adverse life events, which can increase stress and risk for depression and anxiety. Cognitive rigidity, problems with emotion regulation, and intolerance of uncertainty associated with ASD can predispose this population to higher levels of anxiety and depression.2 Emotional regulation deficits may be a transdiagnostic phenomenon that underlies features of ASD as well as anxiety and other psychiatric comorbidities.3
The Autism Comorbidity Interview (ACI) is a semi-structured interview that utilizes the Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS) with adaptation to increase validity in the ASD population. Additional screening questions and coding options were added to the ACI to help distinguish core features of ASD from features of other psychiatric disorders.
The ACI was used to assess psychiatric comorbidity in 109 children with ASD aged 5 to 17 years.4 Findings indicate that 72% of the children had at least one additional DSM-IV psychiatric diagnosis. Anxiety disorders were most common, followed by ADHD (Figure).
Assessment of comorbid psychiatric disorders
Screening instruments designed for psychiatric conditions in the general population may not adequately differentiate features of ASD and can result in overdiagnosis. However, there are several validated disorder-specific tools that have been specifically developed to assess for comorbid disorders in children and adults with ASD (Table 1). Features of ASD can appear to overlap with symptoms of other conditions making it difficult to distinguish symptoms that relate to the core features of ASD versus symptoms of other psychiatric disorders (Table 2).
General considerations for assessing psychiatric comorbidity in ASD
1) Establish a baseline. It is important to establish an individual’s baseline for when he or she has functioned best. For psychiatric conditions that are episodic (eg, mood disorders) or those that appear later in development (eg, OCD, psychosis), it is important to distinguish baseline behaviors and functioning from distinct changes in symptoms that are expected with the onset of a co-occurring psychiatric condition.
2) Assess for medical comorbidity. Assess for medical problems that can exacerbate emotional and behavioral symptoms, particularly in less verbal people.
3) Factor in genetics. Some genetic syndromes are known to be associated with psychiatric conditions and behavioral phenotypes. This can help with more targeted screening (eg, fragile X syndrome has a higher prevalence of anxiety and ADHD, Williams syndrome has a higher prevalence of anxiety, and 22q11 deletion syndrome is associated with higher prevalence of psychosis).
4) Consider symptoms in the context of developmental level. Comorbid conditions should be considered if there are symptoms that are beyond what would be expected for an individual’s mental age and developmental level.
Dr Siegel is Vice President Medical Affairs, Developmental Disorders Service, Maine Behavioral Healthcare, Portland, ME; he is also Associate Professor of Psychiatry and Pediatrics, Tufts University School of Medicine, Boston, MA. Dr Collins is a Child and Adolescent Psychiatrist, Developmental Disorders Program, Sprint Harbor Hospital, Center for Autism and Developmental Disorders, Maine Behavioral Healthcare. The authors report no conflicts of interest concerning the subject matter of this article.
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