LINKöPING, Sweden, June 17 (UPI) -- Having a diagnosis of epilepsy in childhood increases risk for autism spectrum disorder, though just having a family member with the condition may also significantly raise the risk.
Siblings and offspring of people with epilepsy are two-thirds more likely to be diagnosed with autism spectrum disorder, according to a large review of medical data by researchers in Sweden.
Between 20 and 30 percent of children with autism spectrum disorder develop epilepsy by the time they are adults, according to the National Institutes of Health.
"The goal is to find out more about how these two diseases may be linked so that treatments may be developed that will target both conditions," Dr. Heléne Sundelin, a researcher in the pediatrics department at University Hospital in Linköping, Sweden, said in a press release.
For the study, published in the journal Neurology, researchers reviewed medical records for 85,201 people with epilepsy, as well as 80,511 of their siblings and 98,534 of their offspring collected in the Swedish Patient Register, comparing each person with epilepsy to five people of similar age, sex and from the same country who do not have it.
During a six-year follow-up period, 1,381 study participants with epilepsy and 700 without it were diagnosed with autism, suggesting an overall 1.6 percent chance of receiving an autism diagnosis if a person has epilepsy compared to a 0.2 percent chance if they do not. For people diagnosed with epilepsy as a child, the chance of an autism spectrum disorder diagnosis was 5.2 percent.
Overall, researchers found a 63 percent chance of developing autism if a sibling or parent has epilepsy, with offspring of mothers with epilepsy at a 91 percent chance for autism and 38 percent chance if their father has it.
While further research is required to understand the risk factor and genetic relationship between the epilepsy and autism, the researchers say the link is clear.
"Individuals with epilepsy are at increased risk of autism spectrum disorder, especially if epilepsy appears in childhood," researchers wrote in the study. "Further, autism spectrum disorder is more common in the siblings and offspring of individuals with epilepsy, suggesting shared etiology."