An Evaluation of Measures Associated with the Differential Diagnosis of Autism Spectrum Disorder Within a University-Based Clinic Sample

This line of research investigates potential barriers clinicians may face when identifying appropriate diagnostic methods and treatment services when evaluating individuals for ASD within various contexts (e.g., research, clinical). Each study examines diagnostic procedures and intervention methods within different sub-populations of ASD (e.g., simplex, multiplex) with the aim to identify more effective diagnostic and treatment modalities based on different clinical phenotypes. The first and third studies explored issues surrounding diagnosis of ASD in research and clinical contexts, respectively. The first explored these issues within a homogenous simplex ASD population, whereas the third examined diagnostic procedures within a heterogeneous mixed clinical population. The second paper examined treatment outcomes and identified barriers to clinician and family adherence to a clinical intervention program developed for young, minimally verbal children with ASD.

The first paper, “Factors Associated with the Timing of Autism Spectrum Disorder Diagnosis Amongst Simplex Families,” explored various demographic and clinical factors (race, ethnicity, gender, child intellectual functioning, socioeconomic status [SES], history of regression, and language development history) associated with age of ASD diagnosis using a large nationwide research sample from the Simons Simplex Collection (SSC). This initial study focused on barriers to diagnosis within research settings given that the SSC is one of the largest repositories for ASD research. The extant literature on this topic paints a murky picture with regard to the role of child and family demographic factors of when a child receives an initial ASD diagnosis, and no study to date has examined the critical role of expressive language development in the early identification of children with ASD. Results indicated that Asian and Hispanic children are diagnosed at younger ages than Caucasian children within our sample. Additionally, children who developed phrase speech at younger ages received diagnoses earlier than those with delayed speech, and those with reported skill regression received diagnoses earlier than those with no loss of previously acquired skills. However, these characteristics only accounted for 2% of the variance in our model, implying that other factors are more salient as to when a child receives an ASD diagnosis within this population of simplex families. We hypothesize that something within current ASD assessment processes may be contributing to misdiagnosis and missed diagnoses, rather than individual child characteristics, which in turn may be influencing the timing of diagnosis.

To learn more about potential barriers and benefits of interventions for children with ASD in a clinical setting, the author aided in assessing a six-week clinic-based language intervention program aimed at improving communication skills for young, minimally verbal children with ASD. This second manuscript, “An Evaluation of Behavioral and Developmental Communication Interventions for Children with Autism Spectrum”, evaluated the feasibility of enrolling, retaining, and treating children with ASD, as well as assessed outcomes after treatment between the two intervention approaches: behavioral and developmental. Results revealed substantial gains in word count and notable gains observed in gesture use and non-word vocalizations within the clinic setting as well as by parents at home. Verbalizations (single words and word combinations) showed the strongest increase from pre-treatment to post-treatment. Changes in overall ASD symptomatology were largely observed in the communication domain as these behaviors were most notably improved from pre-treatment to four-month follow-up. In regards to treatment effects between the two interventions, behavioral and developmental, the behavioral group had greater gains on a measure of functional communication from pre- to post-treatment, whereas the developmental group had more parent-reported gains from post-treatment to four-month follow-up. Lastly, results revealed that the intervention program was both acceptable and feasible to parents, with high rates of satisfaction and notable treatment gains. The most commonly endorsed barriers to consistent participation included the cost of the intervention as well as the amount and clarity of requested questionnaires. Feedback from clinicians was generally positive but highlighted the need for more in-depth training of each approach and modifications to the training materials to improve clarity and familiarity with the interventions.
These findings support the intervention’s benefit to targeted language skills for this sub-population of young, minimally verbal children with ASD, as improvements in language exceeded other ASD related-areas, such as repetitive behaviors and social interactions. Additionally, the program was well accepted by participants with noted benefits, supporting continuation of the clinic-based program. Most importantly, this pilot data suggest that young, minimally verbal children with ASD can benefit from both short-term behavioral and developmental interventions by improving basic communication skills (e.g., increase in vocabulary, non-verbal gestures), which subsequently reduced ASD symptomology as reported by their parents. Future, larger efficacy studies on interventions with this ASD sub-population are needed to further explore the impact of short-term targeted language interventions within a clinical setting.

The third study, “An Examination of Measures Associated with the Differential Diagnosis of Autism Spectrum Disorder Within a University-Based Clinic Sample,” aims to build on informing diagnostic practices within a clinical setting. Within the literature, there is much debate as to whether past or current nosological systems possess the necessary sensitivity and specificity to accurately identify ASD (McPartland, Reichow, & Volkmar, 2012; Wilson et al., 2013). Within research settings, diagnostic batteries tend to be more rigorous and standardized, allowing for less variation in diagnostic procedures (Barbaresi, Colligan, Weaver, & Katusic, 2009; Matson & Kozlowski, 2011). There is also a further emphasis on extensive training on ASD measures; thus, researchers and clinicians working on ASD-specific research studies tend to be more experienced in working with the ASD population (Barbaresi et al., 2009; Matson & Kozlowski, 2011). In contrast, within clinical settings, batteries are more varied due to timing and availability of resources (Barbaresi et al., 2009; Matson & Kozlowski, 2011). Additionally, professionals have varying levels of expertise in making ASD diagnoses, as they have differing levels of clinical training and experience (e.g., clinical psychologist, school psychologist, speech and language pathologist) (Barbaresi et al., 2009; Matson & Kozlowski, 2011). In addition to the vast heterogeneity of diagnostic procedures across settings, a dearth of research exists on how to distinguish ASD from other neurodevelopmental or psychiatric disorders with overlapping symptoms (Matson & Cervantes, 2014). This third paper aimed to fill that gap by exploring the role cognitive, autism-specific, adaptive, and behavioral measures play in determining a clinical classification of ASD in comparison to other neurodevelopmental or psychiatric disorders within a university-based clinic sample. Findings from this third study provided insight into which measures were most salient in the differential diagnostic process among our ASD sub-population, as well as offered preliminary data about the qualitative and quantitative utility of the ADOS in the diagnostic process.