Sleep Apnea Impacts Cognitive Function in Multiple Sclerosis Patients

Obstructive sleep apnea and sleep disturbances are linked to diminished cognitive ability in patients with multiple sclerosis (MS), according to findings published in Sleep.

Researchers from the University of Michigan studied 38 MS patients in an overnight laboratory and underwent a comprehensive MS specific cognitive testing battery in order to examine the associations between cognitive performance and polysomnographic measures of obstructive sleep apnea in this patient population. The patients performed seven cognitive tests, measuring things like word list recall, calculation, and reproducing figures and pictures.

“Since obstructive sleep apnea is a treatable condition that is also commonly seen in MS, we wondered, ‘What if some of the thinking and processing difficulties that MS patients experience do not stem directly from the MS itself, but from the effects of sleep apnea or other sleep problems?’” co first author and principal investigator Tiffany Braley, MD, MS, explained in a press release.

The researchers found that 33 of the 38 total patients met the criteria for obstructive sleep apnea during the overnight stay.

The researchers also found that apnea severity measures accounted for between 11 and 23 percent of the variance in cognitive test performance. They noted particular cognitive decline among areas like attention and various memory problems — such as for words and images – and working memory (problem solving function and decision making) were linked to poorer sleep.

“Current MS treatments can prevent further neurological damage, but do little to help existing MS symptoms and damage,” Braley said. “Our focus on sleep is part of a larger collaborative initiative to identify previously overlooked but nonetheless treatable conditions that could be affecting patients with MS. Identifying and successfully treating conditions like OSA could help us find new ways to improve the cognitive function in MS.”

The researchers want to duplicate their findings among a larger patient cohort and treat the obstructive sleep apnea patients with positive airway pressure therapy (CPAP). In their new trial, they hope to determine whether cognitive function improves in MS patients who get treated for their sleep apnea.

The study authors also want to inspire more conversations in the neurology clinic and hope that clinicians are asking their MS patients about sleep. They hope that MS patients are able to “openly discuss sleep concerns with their neurologist,” the study authors concluded.