Seizure disorders and epilepsy are frequently reported medical comorbidities in individuals with autism. While a correlation between the two exists, how they influence each other has yet to be determined. Researchers are still exploring whether autism leads to seizures, seizures contribute to autism, or the two conditions coexist.
Seizures are more common in individuals with autism than in the general population. In the general population, fewer than 1% of children (age 17 and younger) develop clinical seizures. By comparison, one of the largest studies aimed at identifying the prevalence of epilepsy in children with autism found that among children aged 13 years and older with ASD, 26% were diagnosed with epilepsy. (Viscidi E.W. et. al, 2013).
Epilepsy in individuals with autism is most common in children over the age of 9. Children age 10 or older with autism had 2.35 times the odds of being diagnosed with epilepsy (p<.001) compared to younger children (Viscidi E.W. et. al, 2013).
What is Epilepsy? What are Seizures?
Seizures are the result of uncontrolled electrical activity between brain cells. Common symptoms of a seizure include involuntary stiffening or jerking of muscles, confusion, loss of consciousness, and unusual thoughts or sensations.
Experiencing unpredictable seizures may be an indication of Epilepsy. This common neurological disorder may be diagnosed if the individual has at least two unprovoked seizures. The qualifier “unprovoked” means that the seizure is not caused by a known event like a head injury, medication reaction, or high fever.
Types of Seizures
Seizures are characterized based on where they start in the brain and how they impact the body. Here are the most common types of seizures identified in individuals with autism:
Generalized tonic-clonic seizures affect both halves of the brain and include both stiffening of muscles (tonic activity) and twitching or jerking (clonic activity). They may also be called generalized onset motor seizures.
Partial or focal seizures start in one area of the brain. They may cause a loss of awareness or the person may remain fully aware during the episode. These are the most common type of seizure among people with epilepsy. However, people with autism and epilepsy are more likely to experience generalized tonic-clonic seizures (Bolton P.F. et al., 2011).
Febrile seizures are experienced by children aged 3 months to 6 years. They occur when the child has a high fever. They may be either general or focal in nature. In some cases, febrile seizures may precede the development of epilepsy.
For more on different types of seizures visit the Epilepsy Foundation.
How Researchers are Exploring the Link
Epilepsy and autism may share similar genetic risk factors. Researchers have identified certain gene mutations that occur in both autism and epilepsy. Studies have found that siblings of children with autism are more likely to have epilepsy.
Some research has found a correlation between epilepsy and regression of mental functioning in children with autism. (Hrdlicka et al., 2004). Other studies have supported these findings, discovering that for a one standard deviation increase in IQ, the odds of having epilepsy decreased by 47% (p<.001) (Viscidi E.W. et. al, 2013). The causal relationship between the two conditions has yet to be established. It is complicated by the fact that intellectual disability is a known risk factor for epilepsy. (Ewen, J.B. et al. 2019)
Sex may also play a role. Studies have found a greater prevalence of epilepsy in autism among females. However, when looking at the total sampling of individuals with epilepsy, males were more likely to have autism than females. More research is needed to identify what role, if any, sex plays in the connection between autism and seizures. (Lukmanji S. et al, 2019)
Even in children with autism who do not have observed seizure activity, researchers have identified abnormal Electroencephalogram results. EEG’s measure of electrical activity in the brain. One study found that 80% of children with ASD had abnormal EEG (Gubbay et al. 1970). Some researchers postulate that these electrical events in the brain may impact the severity of autism symptoms (Boutros N.N. et al. 2015).
Related Disorders that Also Involve Seizures
Other disorders related to autism often involve seizures. These include:
Landau-Kleffner Syndrome – A rare form of epilepsy that manifests as a loss of language. It usually develops when a child is between 3 and 7 years old. Often diagnosed in conjunction with autism, it is twice as common in males compared to females. Approximately 70% of individuals with Landau-Kleffner Syndrome develop epilepsy. Their seizures tend to be infrequent and may occur with or without convulsions.
Rett Syndrome – A neurological disorder affecting primarily females. Although Rett Syndrome has its own pathology, children with Rett Syndrome often exhibit autistic-like behaviors. Approximately 80% also have epilepsy.
Angelman syndrome – A genetic disorder that impacts the nervous system. Initial symptoms of this disorder typically manifest in the first year of life. They may include Mental and speech deficits, small head size, and epilepsy.
Tuberous sclerosis complex (TSC) – A rare genetic disorder. An estimated 40-50 percent of individuals with TSC have autism spectrum disorder. Approximately 85 percent of individuals with TSC also have epilepsy.
Treatments for Epilepsy in Autism
Currently, seizures in an individual with autism are treated in the same way as seizures in individuals without autism. There is little research on specific treatments for individuals with autism and seizures. Seek out the advice of a qualified physician before starting any treatment regime.
For more on epilepsy and other neurological comorbidities in autism, watch the webinar on Neurological Comorbidities in Autism Spectrum Disorder.