People with sleep apnea who have low oxygen levels while sleeping are at an increased risk of developing epilepsy after age 60, according to a new study funded by the National Institutes of Health (NIH). The findings of the study, published in the journal Sleep, could help researchers better understand the relationship between late-onset epilepsy and sleep disorders while also opening the door for potential treatment options.

“There’s increasing evidence that late-onset epilepsy may be indicative of underlying vascular disease, or neurodegenerative disease, even potentially as a preclinical marker of neurodegenerative disease,” Dr. Rebecca Gottesman, an author of the study, said in a news release. “Compared to other age groups, older adults have the highest incidence of new cases of epilepsy—up to half of which have no clear cause.”

Low Oxygen Levels While Sleeping Triples Risk

Epilepsy is a neurological condition that can cause randomly recurring seizures. According to the Epilepsy Foundation, epilepsy is the fourth most common condition affecting the brain, affecting roughly 3 million Americans and 50 million people worldwide. The Epilepsy Foundation also reports that 10 percent of people will have seizures at least once. Most people are diagnosed with epilepsy if they have two unprovoked seizures or one unprovoked seizure but are at a high risk of more.

Sleep disorders are even more common than epilepsy. According to a research brief published by the U.S. Centers for Disease Control and Prevention (CDC), three in four adults have symptoms of a sleep disorder. One sleep disorder, sleep apnea, is when a person’s breathing stops and starts again many times during sleep. According to the National Council on Aging, roughly 39 million American adults suffer from obstructive sleep apnea, and 936 million adults globally have mild to severe obstructive sleep apnea. Snoring is the most common symptom, affecting up to 94 percent of patients.

In the NIH study, researchers identified individuals with late-onset epilepsy by reviewing data from more than 1,300 participants who had sleep-disordered breathing and cardiovascular disease. The research team found that people who experienced nocturnal hypoxia, which occurs when oxygen saturation falls below 80 percent, were three times more likely to develop late-onset epilepsy than those who did not. Additionally, study participants who reported themselves as having sleep apnea later in life were twice as likely to develop late-onset epilepsy as those without the sleep disorder.

How Does This Affect Prevention Strategies?

Though sleep apnea has been linked to other detrimental effects, the connection to epilepsy has not been noted until now. Sleep apnea’s link to nocturnal hypoxia could mean that chronic low oxygen levels during sleep could change the brain enough to trigger seizures. The research team noted that the study could not determine whether treating or preventing sleep apnea could reduce the risk of epilepsy. Still, it does suggest it could be a target for reducing the risk of late-onset epilepsy.