The Epilepsy Connection: Why are People with Autism at Risk?
Seventy years ago, psychiatrist Leo Kanner published a case study of 11 children with a condition he called "autistic disturbance." One child, a young boy known only as John F., also had convulsions – the first reported link of autism and epilepsy.1, 2
In the intervening decades, researchers have studied the autism-epilepsy connection, but many questions remain unanswered or controversial, including how common it is. Medical articles often estimate that a third of people with autism spectrum disorder (ASD) have epilepsy. However, research studies have reported rates from 5 to 46 percent, and the exact rate is unknown.3
Epilepsy means a person has had more than one seizure that was not triggered by a temporary condition, such as a fever. Seizures vary in types and outward appearance. Someone having a seizure may stare blankly for several seconds, which may be barely noticeable, or his body may shake uncontrollably for a period of minutes.4
Who's at risk?
Some risk factors for epilepsy in autism include:
- Age: Seizures seem to begin most often in "two spikes: the preschool years and the teenage years," said autism researcher Sarah J. Spence, M.D., Ph.D.
- Intellectual disability.
- Genetic conditions, such as tuberous sclerosis complex, Fragile X or 15q duplication syndrome.
- Gender: Girls and women have higher rates, according to some research. 3
Studies that include people with those risk factors tend to report higher rates of epilepsy than studies that don't, which can explain why rates vary widely, said Dr. Spence, a neurologist at Boston Children's Hospital.
Even without specific risk factors, the rate of epilepsy is still higher among people with autism than the 1 to 2 percent rate in the general population. One recent study of 577 children and young adults with ASD – but no genetic, neurologic or metabolic disorders – found that 11 percent had epilepsy.5
Parents should be aware of the possibility of seizures, experts say. "It's a scary proposition for parents, but it's important to be aware of that risk," said Dr. James Rubenstein, a neurodevelopmental pediatrician at Kennedy Krieger Institute and Johns Hopkins Hospital.
Some new research underscores the seriousness of epilepsy and autism. Epilepsy itself brings a higher risk of death, and people who have both epilepsy and autism have a higher mortality rate than people who have autism alone.6
People with ASD also can have different types of epilepsy. "There is no clear 'epilepsy syndrome' in autism," Dr. Spence said.
Some types of seizures may be harder to notice because their symptoms – staring and failing to respond, sometimes with repetitive motions – look like symptoms of autism itself.3
Neurologists, doctors who diagnose and treat conditions of the nervous system, are well aware of the autism-epilepsy connection. When Ruth D. Nass, M.D., of New York University Child Study Center, hears a parent describe episodes of staring and unresponsiveness in a child with autism, she said, she is more likely to order a test for seizures than if the child had, for instance, attention deficit disorder.
"As a neurologist, we tend to err more often on looking more carefully at those types of behaviors. We have pretty sophisticated technology for determining if these behaviors are caused by seizures or not. Treating them with anti-seizure medication can make a big difference in the child's behavior and create more opportunity for learning," Dr. Nass said.
Children being evaluated for seizures usually have an electroencephalogram (EEG) test, in which electrodes are placed on the head to measure electrical activity in the brain. An EEG can detect seizures and other abnormalities.
Neurologists have an arsenal of testing options, including ambulatory EEGs, which allow the tests to be performed for several days at home, or video-EEG monitoring, often done in the hospital.7 Longer EEGs may detect events that might not be found on a 20- or 40-minute routine EEG, Dr. Spence said.
Abnormal findings but no seizures
People with ASD have a higher rate of abnormal findings on EEG tests – such as "epileptiform discharges" – even when they don't have epilepsy or seizures.3
If a seizure is like a fire, then an epileptiform discharge is like a single spark, which increases the chance of a fire, explained Joshua Ewen, M.D., director of the Clinical Neurophysiology Lab at Kennedy Krieger Institute. But doctors don't know if these discharges themselves are necessarily causing problems. "They may be a symptom of a problem," he said.
Like the epilepsy rate, the rate of abnormal EEG findings varies widely, from 4 percent to close to 60 percent, depending on the study. More research could help determine the actual rate of abnormalities and what affect they have, if any, on the expression of that person's autism, according to a study co-authored by Dr. Spence.3
One controversial question: Should children with certain abnormal EEGs – but no seizures – be treated with epilepsy medications, which can have negative side effects?
Dr. Spence wants to find out. She is planning a study to determine if treating certain types of EEG abnormalities with anti-seizure drugs "makes a difference in the developmental pattern" of children with ASD. Could medication help these children with behavioral, language and motor problems? "Maybe this is a new treatment we can offer [to] a subset of kids," she said.
Another source of debate is whether seizures or abnormal EEG findings are related to regression – the loss of developmental skills experienced by a third of children with ASD in early childhood. Studies have had mixed results, Dr. Spence said.
"There isn't a clear, absolute association between regression and epilepsy or epileptiform discharges in autism," she said.
Another as-yet unanswered question: Do seizures or abnormal discharges in the brain cause autism? Or, are they part of whatever is behind a person's autism?
"We don't know the answer to that, and it's a huge question," Dr. Spence said. "There is certainly anecdotal information on both sides of that argument," she said. "Some children with autism develop epilepsy, but when the epilepsy is treated, they still have autism," she said. And many people have autism without having epilepsy or EEG abnormalities.
"On the other hand, we all as clinicians have taken care of kids who very early in life had seizures, and when we treated the seizures, their development got a lot better," she said. She recalled one child with autism who enrolled in a research study. When the child returned for a study visit three months later, he had improved so much he no longer was eligible for the study. "We wanted to know, 'What happened?' The mother said he was diagnosed with epilepsy, put on anti-convulsant medication, and his development took off," she said.
Downloadable brochure, Autism, Epilepsy & Seizures: How to Recognize the Signs and Basic First Aid When You Do, from the Daniel Jordan Fiddle Foundation for Adult Autism.
- Levisohn, P.M. (2007) The autism-epilepsy connection. Epilepsia. 2007;48 Suppl 9:33-5. View abstract.
- Kanner, L. (1943). Autistic disturbances of affective contact. Nerv Child 2: 217–50. Kanner, L. (1968). Reprint. Acta Paedopsychiatr 35 (4): 100–36. View abstract.
- Spence, S.J. Schneider, M.T. (2009) The role of epilepsy and epileptiform EEGs in autism spectrum disorders. Pediatr Res. 2009 Jun;65(6):599-606. View abstract.
- U.S. Centers for Disease Control and Prevention. Retrieved from http://www.cdc.gov/epilepsy/basics/faqs.htm
- Cuccaro, M.L., Tuchman, R.F., Hamilton, K.L., Wright, H.H., Abramson, R.K., Haines, J.L., Gilbert, J.R. & Pericak-Vance, M. (2012) Exploring the relationship between autism spectrum disorder and epilepsy using latent class cluster analysis. J Autism Dev Disord. 2012 Aug;42(8):1630-41. View abstract.
- Pickett, J., Xiu, E., Tuchman, R., Dawson, G. & Lajonchere, C. (2011) Mortality in individuals with autism, with and without epilepsy. J Child Neurol. 2011 Aug;26(8):932-9. View abstract.
- Comprehensive Epilepsy Center, NYU Langone Medical Center. Retrieved from http://epilepsy.med.nyu.edu
Photo of Dr. James Rubenstein courtesy of Johns Hopkins Medicine.