• Data were gathered from electronic medical records at an academic medical center. Subjects were included in the analyses if they were assessed using the Autism Diagnostic Observation Schedule (ADOS; Lord et al., 2000).

• Participants were 221 youth with a mean age of 5.05 years (SD = 3.46 years). Participants were grouped as either having an ASD diagnosis only (ASD only group; N=112) or having a diagnosis of ADHD or ADHD and ASD (ADHD/Dual Diagnosis group; N=47).

• Youth were assessed by a team including a PhD-level clinical psychologist, a speech and language pathologist, and a medical doctor.

Symptoms of Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD) can be similar in presentation. Core symptoms of ASD include impaired social development, communication deficits, and repetitive/stereotyped motor mannerisms. However, children with ASD may also present with attention deficits, hyperactivity, and/or impulsivity. Co-occurring ADHD symptoms are found in approximately 41-78% of those diagnosed with ASD (Gadow et al., 2006). Similarly, symptoms of ADHD include hyperactivity, impulsivity, and/or inattention; youth with ADHD may also present with social and communication impairments as well as significant relationship difficulties. Co-occurring symptoms of ASD are reported in approximately 20-33% of those diagnosed with ADHD (Grzadzinski et al., 2011).

Since overlapping symptoms can produce challenges for diagnostic accuracy, better understanding of symptom presentation and level of impairment is essential for diagnostic differentiation. However, standardized diagnostic measures addressing broadband impairments may not capture differentiation in these symptom profiles effectively. Given the developing field of measurement within child psychopathology, demonstration of appropriate measurement models is an important step to identification of constructs.

The purpose of the present study is to examine the Autism Diagnostic Observation Schedule (ADOS), a standardized diagnostic tool used to assess for symptoms of ASD in order to understand the relation between diagnostic categorization (ADHD alone, ASD alone, or dual diagnosis of ADHD and ASD) and level of socialization/communication impairment in youth assessed for ASD. A preliminary investigation using a subset of data from this sample found that the ADOS was able to differentiate subjects’ social/communication behavior across groups of patients with ASD, ADHD, and a combination of the two diagnoses, suggesting that the ADOS may be used for ruling out a diagnosis for those children with ADHD who also present with symptoms of an ASD (Gabrielli et al., 2012). The present study builds on this work by examining the factor structure of the ADOS.

It was hypothesized that the diagnostic groups would display impairment across the broad measure of social functioning. Additionally, it was expected that the measurement model of the subscales of the ADOS will provide adequate fit across ADHD/ASD groups, and that factorial invariance will be achieved.

Assessment of the Measurement Model of Socialization/Communication Impairments Across Groups of Youth Diagnosed with Autism Spectrum Disorder and Attention-Deficit/Hyperactivity Disorder

Matt Braun, MA1, Joy Gabrielli, MA2, Sonia Rubens, MA2, Brenda Salley, PhD1, Catherine Smith, PhD1, & R. Matthew Reese, PhD1

1Center for Child Health and Development, University of Kansas Medical Center; 2Clinical Child Psychology Program, University of Kansas

RESULTS

Figure 1. Original Structural Model for the BASC-2 PRS

Table 2. Factor Loadings for ASD Only and ADHD Groups

INTRODUCTION

METHODS

CONCLUSIONS

ANALYSES

Indicator Equated Estimates Standardized ASD Only Standardized ADHD GroupLoading Intercept Loadinga Theta R2 Loadinga Theta R2 (SE) (SE)

ADOS Subscales:

Communication 0.714 (0.062)

2.675(0.175)

0.629 0.705 0.432 0.376 0.859 0.141

Socialization 0.818 (0.058)

5.938 (0.277)

0.769 0.392 0.671 0.405 0.836 0.164

Creativity 0.893 (0.056)

0.555 (0.093)

0.811 0.419 0.680 0.621 0.614 0.386

Unusual Behaviors 0.826 (0.058)

0.552 (0.121)

0.758 0.543 0.589 0.615 0.612 0.378

aWithin Group Completely Standardized Solution

Model χ2 df p RMSEA 90% CI NNFI CFIConstraint Tenable?

Configural Invariance 6.771 2 =0.034 0.171 0.036 - 0.323 0.903 0.984 Yes

Loading Invariance 24.104 5 =0.002 0.192 0.107 - 0.285 0.845 0.935 Partially

Intercept Invariance 32.143 8 <0.001 0.178 0.109 - 0.252 0.878 0.918 Partially

Note. Each nested model contains its constraints, plus the constraints of all previous, tenable models. Constraints evaluated with the RMSEA Model Test and CFI Difference Test.

Table 1. Factorial Invariance Testing for Child and Adolescent Groups

Communication Socialization Creativity Unusual Behaviors0

2

4

6

8

10

4.91

9.67

2.19 2.722.47

5.74

0.6 0.55

2.44

3.93

1.59 2.17

Figure 2. Mean ADOS Scores for ASD Only & ADHD Groups

ASD OnlyADHD/Dually DiagnosedMean Difference

CreativitySocializationCommunication

PS(1,1)

LY(2,1) LY(3,1)

TE(1,1) TE(2,2) TE(3,3)

Unusual Behaviors

TE(4,4)

LY(4,1)

ADOSTotal

LY(1,1)

1*

Model Fit: χ2(1, n=221)=7.021, p =.008; RMSEA=.164(.066-.288); CFI=.991; NNFI=.945

Mean Age (Sd) Range

5.05 yrs (3.46) 2.00 – 20.00 yrs

ASD PDD-NOS ADHD Aspergers0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

38%

23% 22%

3%

Diagnostic Categorization

Percent of Cases

Caregiver Type

Parent

Guardian

Other

• A confirmatory factor analysis using maximum likelihood rotation was employed to evaluate the factor structure of the ADOS. Measurement properties were initially assessed by review of the covariances of the four ADOS composites (Communication, Socialization, Creativity, and Unusual Behaviors) and the significance of the loadings onto each composite scale.

• All composite scales were correlated, and all indicators were significantly correlated at the p<.05 level. Modification indices were employed to free a correlated residual (i.e., Communication and Socialization).

• Factorial invariance testing was conducted to determine if the ADOS measurement model was equally representative across ASD only and Dually-diagnosed groups.

• The final confirmatory factor analysis (CFA) for the ADOS demonstrated adequate to excellent fit across indices (See Figure 1). Across the two diagnostic groups, the CFA demonstrated adequate fit in the ASD only dataset (Χ2 (1, n = 112) =6.763, p =0.009, RMSEA (0.087 – 0.399) =.224, NNFI=.852, CFI=.975) and excellent fit in the dually diagnosed dataset (X2 (1, n = 47) =.008, p =0.928, RMSEA (0.0 –

0.125) =.000, NNFI=.999, CFI=.999).

• Factorial invariance testing revealed that the overall structure of the ADOS model functioned in the same way across groups but the subscale factor loadings and subscale means only garnered partial invariance. While further examination of the item-level indicators of each subscale is warranted, these findings provide preliminary support for use of the ADOS with youth who present with varying diagnoses.

• There were differences across groups on mean levels of impairment across all subscales of the ADOS. Therefore, the ADOS appears to be a useful tool for diagnostic differentiation of youth who have ASD alone versus ADHD or dual diagnosis of ADHD and ASD.

• Further understanding of the specific types of impairment across groups on the four subscales may be useful to aid in improved diagnostic differentiation of ADHD and ASD. A CFA examining item-level data would provide more information on how the indicators of each subscale could better inform interpretation of impairment across groups.

REFERENCESGabrielli, J., Rubens, S., Salley, B., Braun, M., & Smith, C. (2012). Examination of socialization and communication deficits in Autism Spectrum

Disorders and ADHD. Poster presentation given at the 2012 National Clinical Child and Adolescent Psychology Conference, October 19, 2012, Lawrence, KS.

Gadow, K. D., DeVincent, C. J., & Pomeroy, J. (2006). ADHD symptom subtypes in children with Pervasive Developmental Disorder. Journal of Autism and Developmental Disorders, 36, 271-283.

Grzadzinski, R., et al., (2011) Examining autistic traits in children with ADHD: Does the autism spectrum extend to ADHD? Journal of Autism and Developmental Disorders, 41, 1178–1191.

Lord, C., Risi, S., Lambrecht, L., Cook, E. H., Leventhal, B. L., DiLavore, P. C., et al. (2000). The Autism Diagnostic Observation Schedule – Generic: A standard measure of social and communication deficits associated with the spectrum of autism. Journal of Autism and Developmental Disorders, 30, 205-223.