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Exploring the Connection between Autism and Epilepsy

Marina Sarris

Date Revised: December 1, 2020

When Dustin Stout was diagnosed with autism, no one mentioned to his family that people on the spectrum face a higher chance of developing epilepsy.

His mother, Denice Stout, did not learn about the autism-epilepsy connection until years later, after Dustin had his first seizure while in middle school. “His seizures were brutal,” she recalls. One time he had a seizure at school that worried a teacher so much that the teacher cried, she says. Stout and her son participate in the SPARK research study to increase knowledge of autism.

Although it may not get a lot of attention, the link between autism and epilepsy dates to 1943. That’s when psychiatrist Leo Kanner first described a condition he called autism in 11 children. One of them, he noted, also had “convulsions,” a type of seizure.1

Since then, scientists have studied this topic, but many questions remain unanswered or controversial, including how many people with autism also have epilepsy. Studies have reported rates ranging from 5 to 46 percent.2 A 2019 analysis found a median epilepsy rate of 12 percent among people who have autism.3 A median number is the one that falls in the middle of a range of numbers.

Regardless of the exact number, the rate of epilepsy in people who have autism is clearly much higher than the 1 to 2 percent rate in the general population, says child neurologist Sarah J. Spence, M.D., Ph.D., co-director of the Autism Spectrum Center at Boston Children’s Hospital. Spence, who has researched this issue. She discusses epilepsy and autism in this free recorded SPARK webinar.

What is Epilepsy?

A doctor may diagnose epilepsy when a person has had two or more seizures that were not triggered by a temporary condition, such as a fever. Seizures are caused by a change in electrical activity in the brain. There are several types of seizures, which may look different from one another, according to the U.S. Centers for Disease Control (CDC).

For example, someone having an absence seizure may stare blankly for several seconds, which may be barely noticeable. During a tonic-clonic seizure, a person may fall down, lose consciousness, and have muscle spasms for several minutes, according to the CDC.

Doctors give anti-seizure medications to treat epilepsy.

Who is More Likely to Have Epilepsy?

Some factors may increase an autistic person’s chances of having a seizure disorder. According to research, those factors include:

  • Age. Seizures seem to begin most often in two spikes — the preschool years and also the teenage to young adult years.
  • Intellectual disability.
  • Genetic conditions, such as tuberous sclerosis complex, Fragile X syndrome, 15q duplication syndrome, or changes to the SLC6A1 gene.
  • Gender. Girls and women with autism have higher rates of epilepsy compared to boys and men.4

Studies that include more people with those characteristics tend to find higher rates of epilepsy than studies that don’t, which may explain why rates vary widely, Spence explains.

Epilepsy can be harmful to a person’s health. One rare risk is Sudden Unexpected Death in EPilepsy, or SUDEP. The estimated rate of SUDEP is about one case per 1,000 people who have epilepsy a year, according to the CDC. People who also have intellectual disability are at greater risk for SUDEP.5,6

Overall, people who have both epilepsy and autism have a higher mortality rate than people who have autism alone.7

Just as autism occurs along a wide spectrum, with differences among people, so does epilepsy, Spence says. People with autism have different types of epilepsy.

The symptoms of some types of seizures, such as failing to respond to one’s name and certain repetitive motions, may even look like symptoms of autism itself.2

“I will explain what seizures look like when I give talks to parents, and I will have 17 people lined up to talk to me afterward who say, ‘My kid is seizing all the time. I never knew this.’ And I will say, ‘Probably not. Let’s talk about the differences between autistic behaviors and seizures,'” Spence says.

Still, she says, even epilepsy experts may have trouble telling if a child is flicking his fingers and staring out of the corners of his eyes, for example, because he has autism, or because he’s having a focal seizure, she says.

Evaluating Children for Seizures

Neurologists who evaluate children for seizures often order a test called an electroencephalogram (EEG). For this test, electrodes are placed on the head to measure electrical activity in the brain. An EEG can detect seizures and changes in brain waves that may occur in someone who has epilepsy. These tests may be performed in a medical office or overnight in a hospital.

Sometimes a developmental regression, such as a loss of language skills, in a child will trigger an evaluation for seizures. About one in five children with autism experience a regression,8 for reasons that are not well understood. In rare cases, a loss of skills may be caused by a treatable seizure disorder, such as Landau Kleffner Syndrome.

People with autism have a higher rate of abnormal findings on EEG tests —such as “epileptiform discharges” — even when they don’t have epilepsy or seizures.2

If a seizure is like a fire, then an epileptiform discharge is like a single spark, which increases the chance of a fire, explains Joshua Ewen, M.D., director of the Clinical Neurophysiology Clinic and Lab at Kennedy Krieger Institute in Maryland. But doctors don’t know if these discharges themselves are necessarily causing problems. “They may be a symptom of a problem,” he says.

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 abnormal findings and what effect they have, if any, on the expression of that person’s autism, according to a study co-authored by Spence.2

Doctors usually do not give anti-seizure drugs to children who have abnormal EEGs, if they are not having seizures. The medications can have negative side effects. “We are taught as neurologists not to treat the EEG; we’re taught to treat the child,” Spence explains. “If the child isn’t seizing, we don’t treat it. But I think sometimes we may need to look at it in a different way.”

She would like to see research into whether autistic children who have certain EEG abnormalities should be prescribed medication, even if they don’t have seizures. “If we treated some of the EEG abnormalities, could we get a little bit of improvement?”

The Big Question about Autism and Epilepsy

So what exactly is the connection between autism and epilepsy? Does one condition trigger the other one? Or do both share a similar cause, such as a genetic change or a difference somewhere in the brain? Experts have debated these questions.

Epilepsy and autism likely have a common source that makes people more likely to develop one or both conditions, according to a 2020 article by two researchers in England. ”Seizures are unlikely to cause autism in most cases,” they said.9

Genetics may link autism and epilepsy, Spence says. Some of the same genes appear to be involved in autism, epilepsy, and certain psychiatric conditions, she says. “I do think there’s a shared mechanism,” she says.

In some cases, certain types of epilepsy that begin in infancy cause delays in language and development, she says. If those “infantile spasms” can be controlled, she says, the child’s development can improve.

But in most cases epilepsy does not cause autism, she says. “There are lots of kids who get their autism diagnoses and then start having seizures,” she says. Controlling seizures in these children will not make their autism disappear, she says.

Life with Epilepsy and Autism

Doctors spent years trying to find the right medicine to control Dustin Stout’s tonic-clonic seizures. In 2019, they found the right one. Dustin’s epilepsy is much better, says Denice Stout, a member of the SPARK Community Advisory Council.

She still watches him to make sure he doesn’t get hurt if he were to have another seizure. “I can’t leave him alone in the bathtub, and I can’t let him walk downstairs by himself,” she explains.

Dustin, who is 23, enjoys watching videos on an iPad, and uses an app and sign language to communicate, Denice says. Like many people on the spectrum, Dustin is very sensitive to bright light and loud noises. On a sunny day, “it’s almost like it hurts him to go outside,” she says. “I think if his sensory issues were gone, he would do so much more.”

She hopes doctors find better ways to diagnose epilepsy and select the right medication for each person.

She also hopes parents of young children will become more aware of the autism-epilepsy link than she was. “I do better with more information, so that I can prepare myself.”

Photo courtesy of Denice Stout.

Resources

View this recorded SPARK webinar, “When Epilepsy and Autism Overlap — What Does it Mean?,” by Sarah J. Spence, M.D., Ph.D., a pediatric neurologist at Boston Children’s Hospital.

References

  1. Kanner L. Nervous Child. 2, 217-250 (1943)
  2. Spence S.J. and M.T. Schneider Pediatr. Res. 65, 599-606 (2009) PubMed
  3. Lukmanji S. et al. Epilepsy Behav. 98, 238-248 (2019) PubMed
  4. Lax-Pericall M.T. et al. Epilepsy Behav. 94, 144-150 (2019) PubMed
  5. Devinsky O. N. Engl. J. Med. 365, 1801-1811 (2011) PubMed
  6. Tellez-Zenteno J.F. et al. Epilepsy Res. 65, 101-115 (2005) PubMed
  7. Pickett J. et al. J. Child Neurol. 26, 932-939 (2011) PubMed
  8. Bradley C.C. et al. J. Dev. Behav. Pediatr. 37, 451-456 (2016) PubMed
  9. Besag F.M.C. and M.J. Vasey Child Adolesc. Psychiatr. Clin. N. Am. 29, 483-500 (2020) PubMed