Epilepsy is a neurological disorder that causes recurrent seizures. The condition affects approximately 2 million Americans and while the cause is largely unknown, researchers have discovered that schizophrenia is a possible risk factor, according to BBC.

Scientists in Taiwan analyzed the data of more than 16,000 patients with both conditions and found that schizophrenic patients are reportedly six times more likely to be diagnosed with epilepsy than those without mental disorder.

Researchers at Taichung’s China Medical University Hospital used information from the Taiwan National Health Insurance database recorded between 1999 and 2008, according to the news source.

In some cases, epilepsy is the result of a birth defect in the brain or a head injury, but this new research supports previous studies linking epilepsy with evidence of a mental illness.

According to Dr. Manny Bagary, a consultant neurophysicist in the U.K., it may also be a caused by the “LGI1 or CNTNAP2 genes, which have been associated with seizures and psychosis.”

“We have been aware that epilepsy sufferers seem to have an increased risk of psychosis, but this is the first convincing study to suggest that people with schizophrenia could also be at risk of developing epilepsy, suggesting [that] a bidirectional relationship has been found,” Bagary told the news provider.