In both of these measures, major disorders are keyed to DSM-IV and ICD-10. Also, they can be completed in about 10 minutes; this aspect is important because these scales give the clinician a quick and convenient way to screen for the most common psychiatric conditions in ASDs. However, none of the scales are comprehensive. Therefore, some other less frequent comorbid disorder may go undetected. As with any test, clinical judgment is key. Nonetheless, PAC has proved useful for differentiating OCD from ASDs, and the ASD-Comorbid child version has proved useful in differentiating depression from ASDs.
The case vignette outlines the process discussed above in reaching a comorbid diagnosis with ASDs.
Mr and Mrs X brought their 6-year-old son, Zach, for assessment. They reported that Zach had developed some single word language skills at age 1 but lost all verbal skills by age 21⁄2. Developmental milestones such as crawling and walking were delayed, and toilet training was impossible. As an infant, Zach was difficult to console, made little eye contact, and did not smile while playing with others. As a toddler, his lack of social skills became more and more apparent: he would often sit alone in day care lining up blocks. In his current school program, his teachers were seeing similar social withdrawal behaviors and frequent episodes of physical aggression, self-injurious behavior (ie, slapping the sides of his head), and crying. His parents had observed similar behaviors as well.
Mr and Mrs X reported that over the past year, approximately 1 to 2 times each month, Zach refused meals, slept more than usual, and had significantly more episodes of physical aggression, self-injurious behavior, and crying over 3 to 4 days.
Antecedent behavior consequence (ABC) forms and sleep logs were given to the parents to complete daily. Assessment began with the Autism Diagnostic Interview–Revised (ADI-R) and Autism Spectrum Disorders Diagnostic in Children (ASD-DC), which indicated significant impairments in the 3 core areas associated with ASD: social, communication, and stereotyped behaviors. The Stanford-Binet Intelligence Scale, fifth edition, was administered; however, a basal could not be achieved. The Bailey Scales of Infant Development indicated that he was in the profound range of impaired cognitive functioning. The Vineland Social Maturity Scale indicated that he was in the profound range of adaptive functioning.
To address the challenging behaviors, the QABF was administered and the child was observed in the clinic and at school. Results showed that physical aggression, self-injurious behavior, and crying served primarily as a communication function used to receive tangibles and to escape undesired activities. However, during periods of sleep and appetite disturbance, a clear function for the increase in physical aggression, self-injurious behavior, and crying could not be identified. Behavioral graphs of data from the sleep logs and ABC forms confirmed a significant increase in the frequency and severity of challenging behaviors during times of sleep disturbance with no environmental changes (antecedents and consequences remained consistent). The Autism Spectrum Disorder Comorbid for Children (ASD-CC) was administered and results revealed a clinically significant elevation on the worry/depressed subscale: a significant number of depressive symptoms were endorsed compared with children with ASD without a comorbid diagnosis.
Based on the results of the full assessment, including observations, parent interview and standardized assessments, diagnoses of autistic disorder and depressive disorder NOS were assigned.
Accurate diagnoses based on all 4 parameters cited above have important implications for treatment. When comorbid psychopathology is present, effective interventions will likely be multifactorial. Accurate diagnosis is particularly important in present-day practice because medications and psychosocial interventions are becoming more and more disorder specific.
The dynamic nature of ASD over the long term is being recognized. Fecteau and colleagues17 point out that ASD symptom profiles may change considerably over the life span. The same is true of comorbid psychopathology because onset can vary and severity of symptoms can wax and wane. The evaluation of treatment effects using systematic measures of core symptoms as intervention progresses is essential. Similarly, even when stable, effective treatment is established, there is no assurance that advancing age and changing environmental status will not lead to the need for periodic reevaluation. Addressing all these variables in a life span model should be considered.
Accurate diagnosis is essential if the clinician hopes to provide effective treatment. Many children and adults with ASD are mislabeled or misclassified. Siklos and Kerns18 found that on average, parents visited more than 4 professionals over 3 years before receiving an accurate diagnosis. The most impressive aspect of these data, in our view, is that parents had the perseverance and willingness to expand the level of energy and family resources needed to achieve a correct assessment. They deserve better.
Comorbid psychopathology further complicates the ASD diagnostic picture. However, a systematic, stepwise, evidence-based approach can lead to accurate identification of all relevant problems experienced by the individual with ASD. The recognition that these co-occurring disorders may be present, and the systematic application of diagnostic methods and principles should lead to more effective diagnosis and treatment.