Characterization of Children with Epilepsy and Autistic Disorder

Background: The presentation of Autistic Disorder (AD) in individuals with epilepsy is under-acknowledged and poorly understood. Recent research is suggestive of an elevated rate of the behavioural traits representative of AD, and many children with epilepsy may in fact meet the diagnostic criteria for AD (Boel, 2004; Clark et al., 2005; Steffenburg et al., 2003). 

Objectives: The present study sought to characterize a group of children presenting with epilepsy and AD, through consideration of both the AD clinical phenotype, seizure history variables, and cognitive, language and adaptive behavioural functioning.

Methods: 23 participants with epilepsy and AD (EPI/AUT group) aged 5 to 12 years were matched (based on age and gender) to 23 participants with epilepsy who were not identified as having AD (EPI group), in order to consider group differences with regard to seizure history. In considering group differences in AD clinical phenotype, the participants composing the EPI/AUT group were matched to 23 participants with AD and not epilepsy (AUT group), and scores on AD diagnostic measures (ADOS and ADI-R) were compared. All three participant groups were compared for differences in cognitive, language, and adaptive functioning. Within group comparisons for gender and AD diagnostic history were considered for the EPI/AUT group.

Results: The EPI group was found to be functioning significantly better than the EPI/AUT and AUT group in terms of cognitive, language and adaptive functioning. No significant differences on these domains were evident between the EPI/AUT and AUT groups. Consideration of seizure history revealed that the EPI/AUT group was significantly more likely to be on antiepileptic drug (AED) polytherapy, to have a younger age of seizure onset, and have a higher seizure frequency when compared to the EPI group. No significant differences in AD symptom expression on diagnostic measures (ADOS and ADI-R) were identified between the EPI/AUT and AUT groups. The duration of autistic regression was found to be significantly longer in the EPI/AUT group compared to the AUT group. AD in the EPI/AUT group was diagnosed at a significantly older age, and group members were significantly less likely to have received AD-specific treatment than the AUT group. It was found that 60.9% of the participants in the EPI/AUT group had not been diagnosed with AD prior to involvement in the current study, and the reasons for delayed diagnosis remain unclear. Females in the EPI/AUT group were found to have significantly lower verbal intellectual functioning, a younger age of seizure onset, and to be more often treated with AED polytherapy when compared to males.

Conclusions: The success of initiatives to characterize the presentation of epilepsy/AD is important in increasing awareness among healthcare professionals of this comorbidity, so as to facilitate both timely diagnosis and access to appropriate treatment. Results of the current study suggest that although the AD clinical phenotype is similar, a diagnosis of AD is often not made for individuals with epilepsy.  Particular seizure history variables and female gender may represent differentiating factors for comorbid epilepsy/AD.