Frequency of Autism Spectrum Disorder Among Children with Cerebral Palsy, Metropolitan Atlanta Developmental Disabilities Surveillance Program, 2006-2008

Background:  

Cerebral palsy (CP) is primarily a disorder of movement, but is often accompanied by disturbances of sensation, perception, cognition, communication, and behavior.  Information on the frequency of co-occurring neurodevelopmental disorders is useful to guide treatment and service decisions at both the individual and population levels and may also provide clues to shared risk factors or etiologic pathways.  Previous studies have suggested that the frequency of autism spectrum disorders (ASD) among children with cerebral palsy (CP) is higher than the prevalence of ASD in the general population, but information from population-based studies is limited. 

Objectives:  

The goals of this study were to examine the frequency of ASD among children with CP identified from a population-based surveillance program in metropolitan Atlanta, Georgia.  The frequency of ASD by demographic characteristics, CP subtype, walking ability, co-occurring intellectual disability (ID), and co-occurring epilepsy was also examined.

Methods:  

We used data from the 2006 and 2008 surveillance years of the Metropolitan Atlanta Developmental Disabilities Surveillance Program (MADDSP).  Children were included if they resided in the five-county surveillance area during the surveillance year, were born 8 years prior to the surveillance year, and met the MADDSP case definition for CP.   Determination of ASD case status was made using MADDSP methodology. Characteristics included sex, race/ethnicity, CP subtype, co-occurring ID, co-occurring epilepsy, and walking ability. Frequency tables using chi-square statistics were used to examine differences in the frequency of ASD by these characteristics.

Results:  

Combining case counts for both surveillance years, 358 children met the MADDSP case definition for CP; of these, 27 (7.5%) also met the case definition for ASD.  The frequency of ASD among children with CP did not differ significantly by sex, race/ethnicity, CP subtype, or co-occurring epilepsy, but was higher among children with intellectual disability compared to those without (10.6% vs 5.1%, p=0.05).   Among 241 children with CP with available data on walking ability, ASD frequency was higher among those who could walk independently compared to those with limited or no walking ability (11.1% vs 2.3%, p = 0.01).

Conclusions:  

The reasons for a possibly elevated frequency of ASD among children with CP compared to the general population are not known, but common risk factors or etiologies might play a role. Research regarding pathways of CNS damage in ASD could potentially benefit from the current body of knowledge regarding specific types and mechanisms of CNS damage associated with CP. The lower frequency of ASD among children with limited to no walking ability suggests that clinicians should be alert to the possibility of ASD among children with CP, especially those with severe motor impairment, to ensure that ASD is identified and these children receive appropriate treatment and support.  Diagnostic tests for ASD should accommodate children with disabilities, including those with physical disabilities such as CP.