Modifying Symptom and Diagnostic Criteria for Additional Psychiatric Disorders in ASD: What Is the Evidence?

Background:   Research has consistently demonstrated that a high proportion of people with ASD experience additional mental health problems and fulfil the diagnostic criteria for other psychiatric disorders, such as ADHD, oppositional defiant disorder, anxiety disorders and depression. The reported rates are extremely high, with more than 70% of individuals fulfilling criteria for at least one psychiatric disorder, and this has raised questions about the conceptual diagnostic framework, the breadth of autism spectrum and the appropriate methods to evaluate symptomatology amongst people with ASD. Psychopathology studies have used two assessment methods: (1) standardized instruments, including questionnaires and interviews, applied in the usual way and (2) modified measures, in which the questions and/or symptom criteria have been modified. At present there is a lack of systematic comparison of the two methods and hence no consensus regarding the best strategy for evaluation psychiatric symptoms and disorders in people with ASD.

Objectives:  To improve understanding of the different methods of psychopathology assessment in ASD and their implications for the prevalence, comorbidity and risk factors.

Methods:  A systematic review of articles reporting on the prevalence and co-occurrence of psychopathology amongst people with ASD is undertaken. Databases used to ascertain articles were Medline, PsycInfo and PubMed, which were searched for the last 20 years. This includes both clinical and population-based samples but is limited to main areas of psychopathology, including behavioural (oppositional defiant and conduct) disorder, affective (anxiety and mood) disorder and ADHD.  As well as classifying studies according to the use of standardized vs ASD-modified assessment criteria, articles are also stratified according to participant age, level of intellectual functioning, and informant used to assess psychopathology.

Results:  Data review and analysis is underway. The focus will be on whether there are systematic differences in the prevalence and patterns of co-occurrence of psychiatric  symptoms and disorders according to the method of assessment and accounting for other factors.

Conclusions: The implications of standardized vs ASD-specific assessment methods will be discussed in light of the findings. Comparison will be made with other instances in which this issue has been explored, e.g., affective disorders in children, psychiatric diagnosis in significant intellectual impairment.