Seizures and Epilepsy and Their Relationship to AutismPresentation Transcript
Seizures and epilepsy and their relationship to autism spectrum disorders Research in Autism Spectrum Disorders 3 (2009) 999–1005 Brian Wells, MPH, MSM
Autism Spectrum Disorders• Autism spectrum disorders (ASD) are five related conditions that all share core symptoms of social and communication deficits as well as rituals and stereotypies• Accompanying these core symptoms are often a host of others problems and disabilities.• Among these difficulties are comorbid psychopathology, challenging behaviors, and other neurodevelopmental disorders such as intellectual disabilities• Given the neurodevelopmental origins of ASD, and the many complicating factors that accompany it, the fact that ASD puts the individual at risk for seizures and epilepsy as well should come as no surprise
Autism Spectrum Disorders• Another concern regarding seizure and epilepsy problems in ASD is simply the large number of persons who display them. Furthermore, these numbers have been increasing in recent years.• Onset of ASD is in early childhood, the numbers are large, and the condition is life long
Autism Spectrum Disorders• Seizures of all types occur in persons with ASD• Two or more seizures of any type (usually within a 3- year period) that are not environmentally induced (e.g., trauma, infection, alcohol withdrawal) are described as epilepsy• Prevalence studies of epilepsy and seizures in general are highly variable for the ASD population. Rates have been reported from 5% to 38%• There have not been many prevalence studies on epilepsy and ASD to date, and most of those have included small sample sizes.• This factor may at least in part account for the fact that considerable variability exists in the current prevalence data.
Autism Spectrum Disorders• Prior studies – Rossi et al. (2000) - 60 inpatients from 12 to 29 years of age with autism. 38.3% of their ASD group evinced seizures/epilepsy. – The 38% figure was also reported by Danielsson, Gillberg, Billstedt, Gillberg, and Olsson (2005) who studied 120 autistic children. – Saemundson, Ludvigsson, Hilmarsdottir, and Rafusson (2007) found seizures in 37% of their 84 autistic child sample – Gabis, Pomeroy, and Andriola (2005) report a co- occurrence of seizures/epilepsy and ASD at 40%. – Gillberg (1987) reported rates of about 1/3 for persons with ASD and seizures/epilepsy. – Finally, on the high end of the seizure/epilepsy and ASD overlap, Oslejskova´ et al. (2008) report a 40% rate.
Autism Spectrum Disorders• A substantial number of studies have concluded that the overlap in seizures and ASD is about 30% of cases or more.• However, a few studies have reported very low overlaps in these problems. – Pavone et al. (2004) reported epilepsy in subgroups with and without comorbid conditions. – Reported 3–55% of the sample by group, with epileptic seizures occurring much more frequently where comorbid disorders were present. – They concluded that seizures were likely due to comorbidity of other disorders and underlying brain dysfunction versus autism.
Nosology• Autistic children with seizures/epilepsy in, general, have lower IQ, less adaptive behavior, more emotional problems, and higher psychiatric drug use.• EEG paroxysmal abnormalities and/or febrile convulsions be used to define the disorder in persons with autism. – In their sample of 106 persons with autism they found the same types of epilepsy seen in the typically developing populations, with idiopathic forms being more common. – Finally, 45% of these individuals first began experiencing seizures after 10 years of age.
Noslogy• Abnormal EEG patterns appear to be a common method of describing seizure and epileptiform activity in persons with ASD• High prevalence of these abnormal EEG and seizures plus the general view that ASD has an underlying neurodevelopmental cause, suggests possible similar neurological pathways across these disorders.• However, abnormal EEGs in ASD do not serve as a means of subtyping ASD• To date, there is a lack of descriptive data on the appearance of seizures in ASD.• Some efforts at looking at EEG patterns have emerged, and it appears that all forms of seizures appear in ASD, although at higher rates than seen in the general population.
Etiology• The general consensus is that ASD is neurodevelopmental in origin. It is further hypothesized that central nervous system dysfunction is neurobiological in origin, thus explaining high rates of abnormal EEG and seizures in ASD• This argument is bolstered by the presence of other central nervous system dysfunctions at higher rates than seen in the general population• One explanation for this overlap of seizures/epilepsy and ASD is an imbalance between excitatory (glutamate) and inhibitory components of neurobiology (gamma aminobutyric acid, GABA).
Austistic Regression• Some have hypothesized that regression from relatively normal development up to age 20–24 months may be related to seizure activity.• It is known that regression in language is associated with seizures or abnormal EEG activity• Up to a third of autistic children may regress• Confusions persist over various definitions of similar disorders to ASD. – Acquired epileptic aphasia and Landau-Kleffner Syndrome (LKS) are often confused with autistic regression due to nonspecific language determination
Autistic Regression• Several authors have proposed a direct link between epilepsy and autistic regression. But, their data is correlational and clear cause and effect relationships are yet to be established. – Shinnar et al. (2001) studied 177 children with language regression. – They concluded that regression earlier than age 3, and being male were most likely to be associated with autism. – Seizures were more common in children over 3 years who regressed but were less likely to be autistic. – Finally, they noted that regression in language was highly correlated to regression in other aspects of functioning such as cognitive and social behavior.
Conclusion• ASD co-occurs with a host of problems such as intellectual disability• Challenging behaviors are often associated with ASD, as is comorbid psychopathology• With respect to seizures, researchers have found that while these disorders are neurological in origin they can be affected by environmental variables and overlapping conditions.• The picture is complex with respect to understanding the causes of the event.• Cause/effect links between seizures and epilepsy to ASD may occur in the future.• At present, much more needs to be learned. Having said that, the clinician should be aware of this high co-occurrence during assessment and intervention.