Epilepsy and autism are relatively common conditions that can have a significant effect on a person’s life. Researchers have been looking for a possible link between them because they often occur together.

The Centers for Disease Control and Prevention (CDC) estimate that 1 in every 54 children, equating to about 1.85%, in the United States has autism spectrum disorder (ASD). Among adults in the U.S., the CDC estimates that about 2.21% are autistic.

Data from 2015 suggest that at least 1.2% of the population in the U.S. have active epilepsy, including children and adults.

Researchers are seeing evidence of a link between epilepsy and ASD, as both conditions affect the brain. If scientists can better explain the link between these two conditions, this could contribute to more effective diagnosis and treatment in the future.

This article will look at ASD, epilepsy, and the evidence for a link between them.

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Doctors typically see ASD and epilepsy as different conditions, but they have some common features.

Epilepsy

Epilepsy is a disorder of the brain. It is a neurological condition that can lead to different kinds of seizures.

In a person with epilepsy, a seizure happens when certain brain nerves fire abnormally. This dysfunction can cause effects over which the person has no control.

There are two main types of seizures:

Focal seizures

About 60% of people with epilepsy have these seizures, which affect just one part of the brain.

During a focal seizure, a person may experience:

  • sensory changes that cause a feeling or sense of something that is not real
  • repetitive or unusual behaviors, such as blinking, twitching, or walking in circles
  • auras, or a sense that a seizure is about to happen

Generalized seizures

Abnormal activity affects both sides of the brain in people who experience generalized seizures.

The specific type of seizure will determine the symptoms:

  • Absence seizures: The person appears to stare at nothing and has slight muscle twitches.
  • Tonic seizures: The muscles become stiff, especially in the back, arms, and legs.
  • Clonic seizures: Repeated jerking movements affect both sides of the body.
  • Atonic seizures: A loss of muscle tone causes the person to fall down or drop their head.
  • Tonic-clonic seizures: These can involve a combination of symptoms.

Autism

ASD is a developmental disorder that represents a broad spectrum of symptoms that vary in severity and type.

Although no two people will likely have the same experience of ASD, common signs and symptoms include:

  • Social interaction: The person may find it hard to communicate or interact with others, and they may respond less easily than their peers during social interactions. They may have difficulty understanding body language, making eye contact, interpreting or showing emotions, and forming relationships.
  • Interests and activities: A person may show patterns of behavior that are narrow and repetitive, and they may have a lower tolerance for change than people without ASD. Changes to a routine can be very distressing for an autistic person.
  • Other features: ASD often affects a person’s fine and gross motor skills, which can lead to balance and coordination issues. These features often develop before social challenges become apparent.

Research: Is there a link?

Research shows that autistic people have a 20% risk of having epilepsy and that people with epilepsy have a 20% chance of being autistic. The reason for this may be that the effects of epilepsy and ASD on brain structure and function overlap.

Autistic people have demonstrated a variety of seizure types. About 20–30% of autistic children develop epilepsy before reaching adulthood.

Various factors may explain this phenomenon. For instance, some research has found that electrical activity in the brains of autistic people displays epilepsy-type discharges more often than in people without the condition.

Factors that increase the chance of both epilepsy and autism

Factors that may increase a person’s likelihood of developing either or both conditions include:

  • Level of cognitive ability and development: Research suggests that autistic people and people with epilepsy are more likely than other people to have learning difficulties and developmental delays. In addition, people with active epilepsy and learning difficulties are more likely to be autistic.
  • The presence of another neurogenetic disorder or other medical condition: This increases the chance of both epilepsy and ASD.
  • Age: Epilepsy appears to be most likely to appear in autistic people during early childhood, adolescence, and young adulthood
  • Sex: Among autistic people, some studies have found a higher incidence of epilepsy in females than in males. Other results have not supported this finding, however.

Children and adults who are autistic and have epilepsy tend to have more severe ASD symptoms and more hyperactivity.

One possible link between epilepsy and ASD is the brain’s electrical activity. Doctors often use an electroencephalogram (EEG) to diagnose epilepsy, as it can record seizures. However, it can also detect epileptiform activity, which is an electrical brain activity related to epilepsy.

By looking at EEG results, researchers showed that at least 23% of autistic children have seizures compared with 0.5–1.0% of neurotypical children.

However, they could not draw solid conclusions, and there is still no clear proof of a link. One possibility is that ASD and epilepsy have overlapping genetic factors. Research into a potential genetic link is ongoing.

A 2015 study noted that people with epilepsy often show behaviors that are similar to those that feature in ASD. People with long-term epilepsy often have difficulty with social interaction, but it is not clear whether this is a sign of ASD or the result of living with a potentially stigmatizing health condition.

However, while people with epilepsy often have social traits that resemble those of autistic people, they do not usually have the other cognitive features of ASD, such as repetitive behaviors. One reason for this could be that epilepsy and ASD share some genetic features, but not all.

Doctors and caregivers of autistic people should look for the following “red flags” as signs that the person is having an epileptic seizure:

  • spells of unexplained staring
  • involuntary movements
  • confusion with no apparent cause
  • loss of bladder control
  • changes in abilities or emotions for no clear reason

The appearance of epilepsy may affect a person’s:

  • language and communication skills
  • thinking and reasoning skills
  • behavior

Doctors call this loss of skills regression. However, this regression does not happen in every case, and researchers need to do more work to understand it.

Anyone who has symptoms of epilepsy should see a neurologist. A correct diagnosis and treatment may help control unusual brain activity and prevent seizures.

Doctors prescribe different treatments for epilepsy and ASD. If there is a link between epilepsy and ASD, there could be implications for future treatment options.

Scientists need to do more research on whether epilepsy drugs could benefit autistic people who do not also have epilepsy. Clinical trials would also need to show that any drug treatment is safe and effective before doctors can prescribe it.

Scientists agree that epilepsy and ASD often occur together, but they have not yet found a clear reason for this co-occurrence.

In the future, a better understanding of both conditions and any possible link between them may lead to more effective diagnosis and treatment.