When kids have a fever, the high body temperature sometimes triggers febrile (ˈfe-ˌbrī(-ə)l) seizures. The fever related seizures typically happen when a child’s temperature rises to 102 Fahrenheit or higher. Doctors have long advised parents that these seizures are not usually dangerous.

However, recent research calls that conventional wisdom into question. Researchers writing in the journal Pediatrics say there’s evidence that febrile seizures may be associated with another undesirable condition.

After analyzing data that was collected over 22 years from nearly 1 million children in Denmark, the study authors report that children who suffer febrile seizures have almost a 30 percent greater risk of developing attention deficit hyperactivity disorder than children who have never had a seizure. More than 1,100 children who had seizures also developed ADHD, researchers found.

The researchers say a similar association also exists between epilepsy, another type of seizure disorder, and an increased risk of ADHD.

Specifically, the report says that kids with either febrile seizures or epilepsy — or both — are nearly three times more likely to develop ADHD than children who have not experienced seizures. While the research did not establish cause and effect, the association held up even after accounting for other contributing factors such as low birth weight and a family history of neurological issues.

The researchers don’t know why seizures and ADHD seem to be connected, but they believe there may be some common genetic risk factors. For parents whose children have fever-related seizures, there’s this message: Be on the lookout for ADHD symptoms such as declining school grades, impulsive behavior or a child’s inability to focus.