Three findings emerged from this report. First, all four patient groups scored higher on ASD symptom scales than healthy youths, with effect sizes in mood disorders appearing particularly large (Cohen d across diagnoses ranged from 0.6 to 3.3 ). These findings extend our previous findings, generated in a subset of subjects from the present sample. Because previous findings did not include data in concurrently assessed healthy subjects, the previous study relied on external norms to draw conclusions about the degree to which patients with mood and anxiety disorders present with high ASD symptom scale scores. The present findings suggest that this previous observation reflects specific associations with mood and anxiety disorders, as opposed to other factors associated with attending our unique research setting.
The second hypothesis, concerning scores in BD or SMD, received only limited support, due largely to the fact that the MDD group scored more similarly to the SMD and BD groups than to the healthy or anxious groups. In fact, independent of impairment, the MDD group did not differ from either the SMD or BD groups on any scale, whereas patients with MDD differed significantly from those with anxiety disorders on the GCC even when controlling for impairment. As expected, however, patients with SMD or BD did show higher scores on some scales than patients with anxiety. Surprisingly, no group differences emerged for the SIDC, controlling for impairment. Third, contrary to our hypothesis, ASD symptom scale scores showed no association with anxiety disorder subtype; that is, with impairment covaried, SoPh, SAD, and GAD did not predict scores on any ASD symptom scale.
These findings suggest that pediatric patients with mood disorder exhibit impaired social reciprocity, language deficits, and behavioral rigidity/stereotypy. Indeed, the present data document associations comparable in magnitude to those observed previously in learning or behavior disorders.7,8,30
Overall CGAS impairment showed moderate associations with ASD symptom scale scores. Nevertheless, for each mood disorder group, relative to anxiety disorders, at least one association with an ASD symptom scale score persisted while controlling for CGAS.
These findings suggest that pediatric mood disorders are associated with high ASD symptom scale scores, indicative of symptoms appearing similar to, but less intense than, those of children presenting to ASD specialty clinics. As such, these findings underscore the need for clinicians to assess symptoms tapped by ASD symptom scales in patients presenting for treatment of various psychopathologies not typically considered ASDs. This includes youths presenting with primary complaints related to mood disorders. By using standardized ASD symptom rating scales, clinicians may identify targets for treatment in patients with mood disorders that they may otherwise overlook. Previous research, in particular, finds that social reciprocity traits reside along a continuum.12,16
The present findings suggest that patients with mood disorders fall at the tail of this continuum: 40% to 80% exhibited profiles above clinical cutoffs.
Of note, the approach used here applies a rating scale developed to assess symptoms of impairment in disorders of social communication/reciprocity among patients diagnosed in another domain, mood and anxiety disorders. Previous research using scales, originally developed for use in one context, such as for screening in the community, and then applied in an alternative context, such as among children presenting for clinical research, raises questions about the degree to which identical meanings of the scales emerges in the two contexts. Thus, in the present study, high ASD symptom scale scores could be conceptualized as manifestations of relatively mild ASDs, overlap between mood and ASD symptoms, or nonspecific correlates of psychopathology. Because the present study represents one of the few to use ASD symptom scales in pediatric patients with mood and anxiety disorders, such questions cannot be answered here and should be a focus of future research. Regardless, our findings suggest that patients with mood disorders may frequently exhibit high ASD symptom scale scores. Clinicians may consider in these patients the utility of treatments, typically used in ASDs, to target social reciprocity and communicative deficits.
These findings may also inform research on ASDs. Recent epidemiological studies find higher rates of ASDs than in samples ascertained previously,1
due at least in part to the identification of many ASD cases with average or superior intelligence and mild impairment.2
These studies generally have not conducted the types of assessments used in the present study to assess mood and anxiety disorders, nor do they typically examine relations among ASD symptoms and psycho-pathologies other than ASDs. Our data raise questions about the degree to which youths with high ASD symptom scale scores would be classified in other settings as having an ASD.
One question raised by these and other published data is whether ASD symptoms should be viewed as correlates of illness severity or of other nonspecific features of developmental psychopathologies. The answer to this question seems to vary by diagnosis and ASD symptom scale. Whereas overall impairment exhibited associations with scores on all scales, associations between psychopathology and ASD symptom scale scores remained even after accounting for impairment, with the exception of the SIDC.
With regard to diagnosis, among pediatric anxiety disorders, level of impairment but not specific symptom profiles predicted ASD symptom scale scores. Because the negative findings in SoPh were unexpected, the finding requires replication. In contrast, high scores occurred in mood disorders, relative to anxiety disorders, independent of impairment. This particularly strong relationship between ASD symptom scale scores and mood disorders may suggest that social and communicative deficits represent more central aspects of pediatric mood than anxiety disorders. Consistent with this possibility, considerable previous research demonstrates a strong association between pediatric mood disorders, or risk factors for such disorders, and perturbations in social function.31,32
Such observations have led to the development of therapies that target social problems in these patients.33
Moreover, mood disorder diagnosis also was a stronger predictor than demographic variables: neither age nor intelligence showed as consistent a relationship with ASD symptom scale scores, although one may expect associations with age in larger samples.
The present findings should be considered in light of significant limitations in sampling and assessment. First, our sample consisted of youths receiving treatment. Moreover, only children eligible for participation in other studies focusing on biology were included. Such samples are not representative of children in the community.34
As a result, our findings require replication in patients with pediatric mood and anxiety disorders identified in various other settings, including both nonresearch clinics and epidemiological samples.
Second, it was not feasible to complete comprehensive assessments of ASDs with measures such as the Autism Diagnostic Observation Scale (ADOS) and the ADI-R because these youths and their families underwent lengthy assessments to confirm diagnoses of mood and anxiety disorders. Moreover, even for the current gold standard measures, the ADOS and ADI-R, questions remain about the suitability of these instruments for assessing pediatric patients who present with mild ASD.15,35
Future work in this group should consider the best means for deriving independent assessments of all of the relevant conditions. Regardless of the precise method that is ultimately chosen for such future work, here, the absence of data for the ADOS and ADI-R clearly represents a limitation. In the absence of such data, it is impossible to state confidently the degree to which some subgroup of subjects in the current study may be conceptualized as having a categorically defined ASD, as typically assessed with the ADOS and ADI-R.
Third, our assessment on ASD symptom scales only occurred at one point in time. Previous research generally views scores on these scales as trait factors, based on observations of stability in various populations. Nevertheless, in studies of patients with mood and anxiety disorders, research on other factors typically viewed as traits, such as scores on personality scales, does find state-related effects. Therefore, future research should examine the degree to which ASD symptom scale scores change following successful treatment. This research may clarify the degree to which elevated ASD symptom scale scores represent signs of an ASD versus correlates of mood disorders.
Fourth, although the present study recruited patients meeting categorical definitions of mood and anxiety disorders, data in epidemiological settings show that mood and anxiety disorder symptoms, like ASD symptoms, may be conceptualized as lying along a continuum. The categorical approach of the present study was used to facilitate our biological studies, designed to test hypotheses about patients with unequivocal signs of relatively severe and impairing mood and anxiety disorders. Such an approach has distinct advantages under conditions in which questions on phenomenology abound. Nevertheless, future studies based on epidemiological samples may consider the degree to which the relations between ASD symptom scale scores and mood symptoms are most appropriately conceptualized as continuous versus categorical in nature.
Our findings have several significant clinical implications. These data should alert clinicians to the importance of using ASD symptom scales as well as structured interviews and observations to identify social reciprocity and communication deficits as treatment targets in pediatric mood and anxiety disorders. For some children, additional therapeutic approaches, such as those typically used in the treatment of ASDs, may be useful to target all relevant impairments presenting in youths with mood and anxiety disorders.