International Meeting for Autism Research (London, May 15-17, 2008): AUTISM SYMPTOMS IN CHILDREN WITH DOWN SYNDROME: RELIABILITY OF DIAGNOSTIC TOOLS AND POTENTIAL IMPACT OF WITHIN-CHILD FACTORS ON SYMPTOM PRESENTATION

Saturday, May 17, 2008

Champagne Terrace/Bordeaux (Novotel London West)

11:30 AM

S. Hepburn , Psychiatry, University of Colorado Denver School of Medicine, Aurora, CO

N. R. Lee , University of Colorado at Denver, Aurora, CO

A. Philofsky , University of Colorado at Denver, Aurora, CO

A. Blakeley-Smith , Psychiatry, University of Colorado Denver School of Medicine, Aurora, CO

K. Ridge , Psychiatry, University of Colorado Denver School of Medicine, Aurora, CO

D. Fidler , Colorado State University, Fort Collins, CO

C. DiGuiseppi , University of Colorado, Denver, Denver, CO

L. Miller , Colorado Department of Public Health and Environment, Denver, CO

C. Robinson , School of Medicine/JFK Partners, University of Colorado at Denver, Aurora, CO

Background: Children with Down syndrome (DS) may be at increased risk for autism. Whether this comorbidity reflects a true neurobiological vulnerability, with potential implications for the genetic underpinnings of autism, or the impact of a significant cognitive impairment is not yet understood. Our clinical observations suggest that child temperament, executive function, and motor skills may also impact this apparent comorbidity.

Objectives: To examine agreement amongst diagnostic tools in this population and to explore how other child factors impact symptom presentation.

Methods: 87 children with DS (ages 2 -11) and their parents participated in evaluations for autism. Measures included: ADOS, developmental testing, ADI-R, VABS, Carey Temperament Scales, and BRIEF.

Results: 9 children (10.3%) met criteria for clinical diagnosis of Autism; 14 (16.1%) met criteria for PDD-NOS. Relying upon clinical diagnosis as the "gold standard", intraclass correlation coefficients were obtained for the ADI-R (Lifetime Codes: ICC = .87; Current Codes: ICC = .81) and for two modules of the ADOS: (Module I: ICC = .93; Module II: ICC = .53). Autism spectrum status on the ADI was strongly associated with diagnostic classifications on Module I of the ADOS (ICC=.84, Lifetime, .81 Current), but not on Module II (ICC= .64, Lifetime, ICC= .28, Current). Correlation of IQ to clinical diagnosis was .52. Discriminant function analysis was used to predict diagnostic status, without using measures from diagnostic tools. Receptive language, EF, and Motor Activity correctly classified 90.3% of cases as on/off the spectrum, and 82.3% of cases on specific diagnosis.

Conclusions: Current diagnostic tools are promising, but have limitations, particularly for children with DS with relatively better expressive language. Children with DS who met criteria for an ASD in this sample tended to demonstrate low activity levels, clinically significant problems in executive function, and poor language understanding.

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