Patients with sleep apnea, nighttime hypoxemia face elevated late-onset epilepsy risk

Key takeaways:

• In models accounting for demographics, hypertension, stroke and more, hypoxemia and sleep apnea were linked to late-onset epilepsy.
• As hypoxemia worsened/dropped, the risk for late-onset epilepsy rose.

Nocturnal hypoxemia and sleep apnea raised the risk for late-onset epilepsy even after adjustment for several risk factors and comorbidities, according to results published in Sleep.

“For the general clinician, this gives one more reason among many to be screening for sleep apnea in appropriate populations and to take seriously the treatment thereof,” Christopher M. Carosella, MD, assistant professor of neurology at Johns Hopkins University, Baltimore, told Healio. “For specialists, it encourages a close working relationship between pulmonologists and neurologists to ensure that they are comanaging patients to ensure the best possible care.”

Using data from the Atherosclerosis Risk in Communities (ARIC) study cohort, Carosella and colleagues analyzed 1,309 individuals to find out how sleep characteristics and sleep apnea impact the risk for late-onset epilepsy through survival analyses.

In addition to causing problems concerning multiple organ systems, Carosella said sleep apnea has previously demonstrated a bidirectional relationship with seizures and epilepsy.

“Patients with epilepsy have a higher prevalence of sleep apnea compared to the general population, and studies have demonstrated that treatment of sleep apnea in persons with epilepsy can reduce seizure frequency,” he said.

Researchers found late-onset epilepsy cases via Medicare claims and collected patient information through polysomnography results.

Following participation in the ARIC/Sleep Heart Health Study (median follow-up, 20 years), 26 of 1,309 individuals had late-onset epilepsy.

Adjustment for several demographics and covariates (diabetes, smoking status, alcohol use, head injury, apolipoprotein e4 alleles, pulmonary function, hypertension, stroke and dementia) revealed a significant link between oxygen saturation less than 80% (hypoxia) during sleep and late-onset epilepsy development (adjusted subhazard ratio [aSHR] = 3.28; 95% CI, 1.18-9.08).

Researchers further investigated this relationship in a sensitivity analysis that broke down hypoxemia into four thresholds: below 75%, 80%, 85% and 90%. As hypoxemia worsened/dropped, the risk for late-onset epilepsy rose.

“Based on these results, we now hypothesize that recurrent nightly hypoxia, especially when severe, may, over time, contribute to the development of epilepsy in late-onset epilepsy,” Carosella said. “The positive counter to this idea is that since late-onset epilepsy occurs, definitionally, later in life, there may be time for clinicians to evaluate and treat potential risk factors such as OSA/nocturnal hypoxia.”

Notably, adjustment for heart failure did not impact the increased risk for epilepsy seen with hypoxemia, according to researchers.

In contrast, there was no significant relationship between apnea-hypopnea index and late-onset epilepsy, which Carosella said was surprising. The risk for this disorder was also not significant when researchers evaluated obstructive apnea-hypopnea index, arousal index, respiratory disturbance index, wake time after sleep onset and sleep duration.

During a different analysis of 2,672 individuals, 313 reported sleep apnea. Of those with sleep apnea, 10 had late-onset epilepsy.

According to researchers, the adjusted risk for late-onset epilepsy was heightened among those who reported OSA (aSHR = 2.59: 95% CI, 1.24-5.39).

“This study may be an indicator that OSA and hypoxia may be a reversible driver of epilepsy development, though much more research would be needed to confirm this hypothesis,” Carosella said.

“Discovering a reversible cause of epilepsy is an aspirational goal for any epilepsy researchers or clinician,” he continued. “We hope this study might be a small first step in that direction and also an encouragement to evaluate and treat sleep disorders in patients with epilepsy.”

Reference:

• Low oxygen during sleep and sleep apnea linked to epilepsy in older adults. https://www.nih.gov/news-events/news-releases/low-oxygen-during-sleep-sleep-apnea-linked-epilepsy-older-adults. Published April 30, 2024. Accessed April 30, 2024.