The core features of an Autism Spectrum Disorder (ASD) relate to deficits in communication, social skills, and repetitive/stereotyped movements. However, individuals diagnosed with an ASD often have concomitant emotional and behavioral difficulties that have a significant impact on their functioning. Knowing prevalence rates of psychiatric symptoms in individuals with ASD and understanding of how these psychiatric symptoms are reported across settings directly impacts diagnostic decisions and treatment planning. Interpretive challenges exist when this information is discrepant or contradictory. Despite the weight clinicians give to reports of psychiatric symptoms from various settings (e.g., parents and teachers), few researchers have examined the nature of cross-informant reporting differences in individuals with ASD.
Clinicians who work with children and adolescents diagnosed with ASD are well aware of the difficulties that these individuals experience beyond the core features typically associated with the disorder. These clinical observations have prompted researchers to examine the prevalence and quality of the co-occurring psychiatric difficulties, with the most common found to be symptoms of anxiety and depression (Howlin, 2000
; Kim, Szatmari, Bryson, Streiner, & Wilson, 2000
; Lainhart, 1999
; Simonoff, Pickles, Charman, Chandler, & Baird, 2008
; Tantam, 2000
), but also including behavioral difficulties (Lecavalier, 2006
), attentional dysregulation (Gadow, DeVincent, & Pomeroy, 2006
; Leyfer et al., 2006
; Simonoff et al., 2008
), and obsessive tendencies (Leyfer et al., 2006
There are several obstacles to quantifying psychiatric co-morbidity in individuals with ASD. These include problems of a) symptom overlap; b) symptom masking; c) interpretation of emotional states; d) misinterpretation of the meaning of symptoms; and e) inherent difficulties with self-report. Furthermore, cognitive deficits and impaired insight may compromise a child’s ability to report or describe symptoms. Studies have used a variety of measures, standardized or otherwise, to assess for the presence and degree of psychiatric symptoms, making it difficult to compare across studies or to arrive at a common consensus.
Despite these obstacles, most studies have found higher rates of psychiatric symptoms in individuals with ASD. For example, Leyfer and colleagues (2006)
found that 72% of the children in their study met criteria for at least one DSM-IV Axis I disorder. More specifically, 44% of the children with autism in their sample met the criteria for a specific phobia, 37% met criteria for Obsessive-Compulsive Disorder (OCD), 31% met criteria for ADHD, and 10% met criteria for Major Depression. In another study, Lecavalier (2006)
found a high endorsement rate of behavior and emotional difficulties in a non-clinically referred sample of individuals with ASD of an average of 9 years of age. Gadow and colleagues have found over half of the children ages 6–12 met criteria for ADHD (Gadow et al., 2006
; Gadow, DeVincent, Pomeroy, & Azizian, 2004
). Morgan et al. (2003)
found that adults with both a learning disability and autism had high rates of depression (20%) and Bipolar Affective Disorder (11%) (Morgan, Roy, & Chance, 2003
). Ghaziuddin and colleagues have noted high prevalence rates of depression in their work with individuals with ASD (Ghaziuddin, Ghaziuddin, & Greden, 2002
; Ghaziuddin, Weidmer-Mikhail, & Ghaziuddin, 1998
) and Howlin noted in her review of adult outcomes in Asperger Syndrome and “able” individuals with autism, that over a third of the reported psychiatric diagnoses were depression often associated with severe anxiety (Howlin, 2000
). In a more recent study, de Bruin and colleagues found that 80.9% of the children with Pervasive Developmental Disorder – Not Otherwise Specified had at least one co-morbid psychiatric disorder (de Bruin, Ferdinand, Meester, de Nijs, & Verheij, 2007
). In sum, all of these studies note a higher rate of prevalence in the ASD populations compared to a typical population, where prevalence estimates of psychiatric difficulties typically range from 8% to 18% (e.g., Roberts, Attkisson, & Rosenblatt, 1998
In addition to direct observation and assessment, clinicians often gather information regarding a child’s emotional and behavioral functioning through the use of behavioral report forms. These forms, filled out by parents, caregivers, and teachers, can be a rich source of information on how the child is functioning across settings and over time. An important consideration when interpreting these behavioral report forms involves informant source; previous research has demonstrated that discrepancies often exist when different informants rate a child’s behaviors using the same measure (De Los Reyes & Kazdin, 2005
; Szatmari, Archer, Fisman, & Steiner, 1994
Ratings can differ for a variety of reasons. The instrument may fail to precisely characterize a specific trait across environmental contexts, such as between school and home, due to differential environmental contingencies. Ratings can also differ due to rater bias wherein discrepant ratings of an individual occur due to differing interpretations of the measurement scale or unique perceptions of the individual being rated (Hoyt, 2000
). A possible exacerbating factor may be inherent in how the measure is designed; that is, many behavioral report forms are constructed to assess state
characteristics, rather than trait
characteristics. State characteristics are more vulnerable to situational variables and thus more prone to discrepant findings across informants and settings. Examples of measures that have discrepant findings amongst informants include the Behavior Assessment System for Children – 2nd
Edition (BASC-2; Reynolds & Kamphaus, 2000
), which reports a minimal relationship between teachers and parents on composite scores for Internalizing Problems, Externalizing Problems, and the Behavioral Symptoms Index. The widely used Child Behavior Checklist (CBCL) and its comparison instrument for teachers, the Caregiver/Teacher Report Form (C-TRF), report inter-rater agreement between teachers and parents ranging from r
= .12 to r
= .44 (Achenbach & Rescorla, 2001b
).Similarly, the Behavior Rating Inventory of Executive Function (BRIEF; Gioia, Isquith, Guy, & Kenworthy, 2000
) reports such a low level of agreement on the Global Executive Composite between teachers and parents that it is common for different conclusions to emerge.
In contrast, inter-rater agreement (e.g., between parent and teacher) tends to be greater when considering autistic symptomatology. These rating scales are likely tapping into more stable, trait characteristics that are less prone to discrepancies amongst informers from different settings. For example, in a study involving 577 children of which 406 had a pervasive developmental disorder, Constantino and colleagues demonstrated that teachers exhibited a high level of inter-rater agreement with parents (r
= 0.72) when assessing autistic severity using the Social Responsiveness Scale (SRS; Constantino et al., 2007
). Given the need to gather information across multiple sources and settings when assessing individuals with an ASD, it is important to use measures that are validated across clinical and educational settings.
This study had several objectives. First, using the parent-report CBCL and its associated instrument for teachers, the C-TRF, we examined a consecutively ascertained population of children and adolescents diagnosed with ASD to estimate the prevalence rates of comorbid psychiatric syndromes and sought to determine whether the various symptoms were either present, absent, or manifested in a range of severity in this clinical sample. Second, in order to determine the reliability of measurements of comorbid syndromes, we examined the extent to which parents and teachers agreed on quantitative characterization of these symptom domains in youth with ASD and their siblings. Using siblings allows for the comparison of psychiatric difficulties in a group of individuals who experienced a similar environment and were rated by the same informant (i.e., the parents). Finally, we attempted to elucidate domains of symptoms that might be better appreciated in home/family environments versus educational settings.