WASHINGTON — Stroke and sleep apnea are associated with lower verbal memory and executive function scores than sleep apnea or stroke alone, study findings indicate.
A majority of stroke and transient ischemic attack patients also have sleep apnea, Jennifer R. Molano, MD, of the University of Cincinnati, said during a session at the American Academy of Neurology 2015 Annual Meeting.
Although it’s well established that stroke can cause cognitive problems, sleep apnea may also cause problems with attention, executive functioning, and daytime sleepiness, prompting Molano and colleagues to question if a combination of both conditions would result in worse cognitive function.
“Sleep apnea is treatable, so if there’s something we can do to prevent cognitive decline, then that would be something that would be very intriguing,” she told Neurology Advisor. “Stroke and sleep apnea have common risk factors and comorbidities that include high blood pressure, obesity, smoking, and diabetes. All of those risk factors can cause inflammation and cause potential issues with cognition down the road.”
Cognitive Performance in Stroke and Sleep Apnea
The REasons for Geographic And Racial Differences in Stroke (REGARDS) Study, enrolled a U.S. cohort of 30, 239 blacks and whites aged ≥ 45 years from 2003 through 2007, with follow-up every six months. A cognitive battery was added in May 2008 and a sleep assessment was included in September 2008.
Tthe researchers measured cognitive impairmentwith the Six Item Screener (SIS) score, verbal memory with Word List Learning (WLL) and Word List-Delayed Recall (WLD) scores, and executive function with Animal Fluency (AF) and Letter Fluency (LF) scores among 22,587 participants.
A SIS score of ≤4 indicated global cognitive impairment. Higher scores on the tests of verbal memory and executive function were associated with better cognition. Sleep apnea was identified by self-report, and stroke was identified by either self-report at baseline or review of medical records prior to completing the sleep assessment.
Approximately 10% of study participants had sleep apnea only, 5% had stroke only, 1% had both stroke and sleep apnea, and 83% were controls.
Among the participants, the stroke-only group was more likely to be older and black, with lower income and education, whereas the stroke and sleep apnea group had more comorbidities.
Overall, mean cognitive performance scores were highest in controls and lowest in those with stroke and sleep apnea. Scores for WLL (controls=16.3, SA-only=15.8, stroke-only=14.5, S+SA=13.3), WLD (controls=6.2, SA-only=5.9, stroke-only=5.4, S+SA=5.0), AF (controls=15.4, SA-only=15.1, stroke-only=13.6, S+SA=13.2), and LF (controls=10.0, SA-only=9.7, stroke-only=8.8, S+SA=8.0) were all P<0.0001.
The analyses were adjusted first for demographics and then for comorbidities, including hypertension, diabetes, body mass index, and daytime sleepiness. Following demographic adjustment, a clear trend emerged, with the stroke and sleep apnea group having the lowest cognitive scores, followed by the stroke-only group and the sleep apnea-only group (mean difference, P<0.0001 for all). Results were still statistically significant after including adjustment for comorbidities.
The stroke and sleep apnea group showed lower verbal memory and executive function scores compared with stroke only, sleep apnea only, or neither groups, making it paramount to screen patients with stroke for sleep issues, especially sleep apnea. Notably, the stroke-only group had the highest global cognitive impairment score.
“Make sure to ask if someone snores, stops breathing,, or gasps for air while sleeping, because that makes them at higher risk for sleep apnea, which may have implications down the road with or without a neurological disorder,” said Molano.
“Sleep apnea itself is a risk factor for stroke and heart disease. Since we know overall health can help with quality of life in patients with neurological disorders, screening for sleep issues and especially sleep apnea is something to keep in mind.”
- Molano JR et al. Abstract S53.005. Presented at: American Academy of Neurology Annual Meeting 2015; April 18-25, 2015: Washington, D.C.