If scientists find a link, this could lead to a better understanding of both conditions and contribute to more effective diagnosis and treatment in the future.
This article will look at some of the evidence of a link between autism and epilepsy.
What is the link?
Autism and epilepsy often occur together. They are seen as different conditions, but they may have some features in common.
Autism and epilepsy often happen together.
Epilepsy is a disorder of the brain. It is a neurologic condition that can lead to different sorts of seizures.
In a person with epilepsy, a seizure happens when certain brain nerves fire abnormally and cause effects that the person has no control over.
There are two main types of seizure.
Focal seizures: These affect just one part of the brain. Around 60 percent of people with epilepsy have this type.
During a focal seizure, a person may experience:
- changes in consciousness
- sensory changes, where they feel or sense something that appears not to be present
- repetitious or unusual behaviors, such as blinking, twitching, or walking in circles
- auras, or a sense that a seizure is going to happen
Generalized seizures: Abnormal activity affects both sides of the brain.
The following may occur:
- Absence seizures: The person appears to stare at nothing, with slight muscle twitches.
- Tonic seizures: The muscles become stiff, especially in the back, arms, and legs.
- Clonic seizures: There are 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: This can involve a combination of symptoms.
Autism spectrum disorder (ASD) is a disorder of childhood development. Symptoms can vary widely in type and severity.
The main ways in which autism can impact a person's life are:
Social interaction: The person will find it hard to communicate or interact with others. They may respond less easily to conversation, compared with their peers. They may have difficulty understanding body language, making eye contact, interpreting or showing emotions, and in 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 their peers. Changes to a routine can be very distressing for a person with autism.
Research: Is there a link?
Epilepsy results from a malfunction in the brain. Autism, too, probably stems from a problem with the brain. The conditions affect different brain structures and functions, but some features overlap.
This has raised the question of whether there might be a biological link.
Scientists and doctors have found that epilepsy is more common in people who also have autism, and that autism is more common in those who have epilepsy. All types of seizures have been observed in people with autism.
- Up to 32 percent of people with epilepsy also meet the diagnostic criteria for autism, according to an article in Pediatric Research.
- Around 20–30 percent of children who have autism develop epilepsy before becoming adults.
A number of factors and features may underlie this link.
Some research has found that electrical activity in the brains of people with autism displays epilepsy-type discharges more often than in people without the condition.
Risk factors for both epilepsy and autism
Factors that may affect the chance of a link include:
Level of cognitive ability and development: Those with autism and epilepsy are more likely to have learning difficulties and developmental delays. In addition, people with active epilepsy and learning difficulties are more likely to have autism.
Having another neurogenetic disorder or other medical condition: This increases the risk.
Age: Epilepsy appears to be most likely to appear in people with autism during early childhood and in adolescence and young adulthood
Sex: Some studies have found a higher incidence of epilepsy in females with autism, compared with males. Other results have not supported this finding, however.
Children and adults who have both autism and epilepsy tend to have more severe symptoms of autism, more hyperactivity, and a lower intelligence quotient (IQ) compared with those who do not have epilepsy.
One review that focused on the link between autism and epilepsy looked at various findings about the brain's electrical activity, using EEG. The review appeared in the journal Pediatric Research.
EEG tests have shown similar brain activity in people with epilepsy and autism.
Doctors often use EEG to diagnose epilepsy. An EEG can record seizures, but it can also detect epileptiform activity. This is another electrical brain activity that is related to epilepsy.
The findings suggested that epileptiform activity is more common in people with autism, even if they have never had a seizure. It is not clear that treating these EEG abnormalities will help with the symptoms of autism.
According to the review, some studies have found high rates of epileptiform EEGs with autism, even when there was no diagnosis of epilepsy. Some scientists believe these abnormalities might have something to do with causing autism.
However, the review could not draw solid conclusions, and there is still no clear proof of a link.
One possibility is that autism and epilepsy have overlapping genetic factors. Research into a potential link is ongoing.
In an article published by ResearchGate in 2015, Dr. Sallyann Wakeford noted that people with epilepsy often show behaviors that are similar to those that feature in autism.
She pointed out that people with long-term epilepsy often have difficulty with social interaction, but questions whether, for some, this is a sign of autism or the result of living with a stigmatizing health condition.
Wakeford also found, however, that while people with epilepsy often have social traits that resemble those of autism, they often do not have the core cognitive features of autism, such as repetitive behaviors.
One reason for this could be that epilepsy and autism share some genetic features, but not all.
When to see a doctor
The website Autism speaks suggests that doctors and others who take care of people with autism should look for the following "red flags" as signs that epilepsy may be present:
If a person with autism shows certain signs, such as staring into space for a while or making involuntary movements, they should see a doctor for an assessment.
- spells of unexplained staring
- involuntary movements
- confusion with no apparent cause
- severe headaches
- sleepiness and sleep disruption
- changes in abilities or emotions without any clear reason
Some researchers have observed that children aged 18–24 months who have autism may lose skills they have already learned if epilepsy appears.
The appearance of epilepsy may affect a person's:
- language and communication skills
- thinking and reasoning skills
This loss of skills is called regression. However, this regression does not happen in every case, and the findings are controversial.
Anyone who has symptoms of epilepsy should see a neurologist. A correct diagnosis and treatment may help to control unusual brain activity and prevent seizures.
Epilepsy treatment and autism
Doctors prescribe different treatments for epilepsy and autism, but if there is a link this could have implications for future treatment options.
Scientists have also looked into whether treating epilepsy in children with autism could benefit both epilepsy and autism.
However, it remains unclear whether drugs for treating epilepsy would benefit people with autism who do not have epilepsy but whose EEG shows epilepsy-type activity.
According to the authors of the above-mentioned review, there is a need for more quality research into whether epilepsy drugs could have any overall benefit for people with autism.
Clinical trials would also need to show that such a treatment is safe and effective before doctors can prescribe it.
When a child with autism and epilepsy receives treatment for epilepsy, scientists say this does not appear to affect the diagnosis of autism. Some, however, have seen improvements in cognition, communication, and behavior when receiving this treatment.
A final word
Scientists agree that epilepsy and autism often occur together, but why and how that happens remains unclear.
In the future, a better understanding of both conditions and any possible link may lead to more effective diagnosis and treatment.