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Aggressive Behaviors in ASD: Prevalence and Correlates in a Large Clinical Sample

Saturday, 4 May 2013: 09:00-13:00
Banquet Hall (Kursaal Centre)
A. D. Hagen1, D. J. Kriz1, S. W. Duvall1, D. Ettinger1, C. Green1, A. P. Hill2, K. Freeman1, J. van Santen2, J. Nigg1, D. A. Fair1 and E. Fombonne3, (1)Oregon Health & Science University, Portland, OR, (2)Center for Spoken Language Understanding, Oregon Health & Science University, Beaverton, OR, (3)Psychiatry, Oregon Health and Sciences University, Portland, OR
Background:  Aggressive behaviors are frequent in Autism Spectrum Disorders (Kanne and Mazurek 2010; Matson and Rivet 2008) and associated with more intensive medical interventions, impairment, and increased demands on caregivers (Lecavalier and Wiltz 2006). Despite the high importance of this subject, it is not well studied.

Objectives:  To investigate the prevalence of aggressive behaviors in ASD children at the time of diagnosis, and to identify age and gender trends and other factors that are associated with them.

Methods:  Data were collected at the Oregon Health and Sciences University (OHSU; Portland, OR) site of the Autism Treatment Network (ATN). Data on 400 diagnosed subjects (83% male; mean age: 5.4 years; range: 2.0 -16.9 years) were available. Aggressive behaviors were measured on the Aggressive behavior scale of the CBCL that provided as well measurements of co-occurring emotional and behavioral problems. Data on parental concerns, autism severity, adaptive behavior, verbal level, medication use, socio-demographic background were available through parental self-reports and standardized professional questionnaires recorded in the ATN database.

Results:  Aggressive behaviors were one of the most frequent (55.6%) parental concerns at referral. 25% of children were scoring in the clinical range for aggressive behaviors as measured by a T-score above 70 on the Aggressive scale of the CBCL. Aggressive behaviors were unrelated to age (p=.25), gender (p=.22), parental education (p=.29), to non verbal status (p=.29), clinical evidence of cognitive delay (p=.32),  autism severity as measured by DSM-IV symptom count (p=.70) and to Vineland standard scores. Aggressive behaviors were strongly related with T-scores falling in the clinical range in all other subscales of the CBCL. Correlations with other factor and total CBCL scores ranged between .33 (Somatic complaints) and .95 (Externalizing score) (all p<.001). Aggressive behaviors significantly increased the likelihood of psychotropic drug prescriptions (43% vs 29%; p=.01) but not that of alternative medicines (33.3% vs 27.3%; NS). We performed further analyses by comparing 88 children scoring above a t-score of 70 on the CBCL aggressive subscale (Agg+) to 183 children scoring under 60 on the same scale (Agg-). Bivariate logistic analyses were performed to identify predictors of Agg+. Results showed the same pattern than in the whole sample with gender, age, Vineland scores, verbal level, and sociodemographic variables bearing no association with presence/absence of aggressive behaviors.  Association with multiple comorbid syndromes were significant, with a particularly strong association with ADHD symptoms. More detailed analyses will be presented alongside results of multivariate logistic regression models.

Conclusions:  Aggressive behaviors are a significant source of parental concern and have consequences in the management (medication or otherwise) of ASD children. Correlates of aggressive behaviors in typical children were weaker or absent in this ASD sample, possibly pointing to a different mechanism and significance of aggression in ASD. Similarly, aggressive behaviors were not predicted by indices of autism severity. High levels of both internalizing and externalizing co-occurring symptoms, especially with ADHD symptoms, are cues for further studies.

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