Sleep Apnea in Multiple Sclerosis May Facilitate Cognitive Decline


A recent study demonstrated that concomitant sleep apnea syndrome may expedite cognitive decline, particularly in attention and concentration, among patients with multiple sclerosis.

In a new case control study published in Multiple Sclerosis and Related Disorders, findings showed a slightly higher prevalence rate of sleep apnea syndrome (SAS) in Japanese patients with multiple sclerosis (MS) than controls.1 Overall, patients with MS with SAS performed worse on cognitive assessments, suggesting concomitant SAS may facilitate cognitive decline in this patient population.

In the study, investigators used Out of Center Sleep Testing (OCST) to detect obstructive sleep apnea (OSA) in patients living with MS (n = 67) and age-matched controls (n = 31). The prevalence rates of OSA, defined by a Respiratory Event Index (REI) score of at least a 5, were 28.4% in the MS group and 25.8% in the control group. REI values (5.2 [±7.9] vs 3.9 [±5.2]; P = 0.509) and number of participants with REI of at least 5 (19 vs 8; P = .793) were similar between both groups.

Top Clinical Takeaways

  • Recognizing and addressing sleep apnea through active screening may be beneficial for Japanese patients with multiple sclerosis (MS) experiencing cognitive decline.
  • The study highlights the statistical association between concomitant sleep apnea syndrome and the decline of cognitive functions, emphasizing the importance of interventions for patients with MS.
  • Despite limitations, such as differences in BMI and sleep stage monitoring, the research highlighted the need to consider sleep apnea as a potential contributor to cognitive dysfunction in MS.

“This study revealed the prevalence rate of SAS in Japanese patients living with MS and the usefulness of OCST for detection of SAS. Patients living with MS showed cognitive decline characterized with attention and concentration, and concomitant SAS facilitated cognitive decline in people living with MS,” senior author Tetsuya Maeda, MD, professor of neurology and gerontology in the department of internal medicine at Iwate Medical University School of Medicine in Japan, and colleagues wrote.1 “These findings suggest that an appropriate intervention for OSA can be beneficial for patients living with MS with cognitive decline. Therefore, active screening for SAS using with OCST should be recommended in MS.”

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Investigators explored clinical features of SAS in patients living with MS and how that might impact cognitive dysfunction with their diseases. Participants diagnosed with the McDonald 2017 diagnostic criteria from Iwate Medical University between April and October 2022 were enrolled.2 Controls were recruited from healthy volunteers with no history of neurological diseases and sleep disorders. Researchers used the Symbol Digit Modalities Test (SDMT) and the Paced Auditory Serial Addition Test 2 (PASAT-2) and 3 (PASAT-3) to assess cognitive functions. Cognitive and respiratory characteristics were also compared statistically between those with or without SAS because of OSA.

For a stricter criterion, investigators applied a cut off REI at least 15 and observed that the prevalence rates decreased to 9.0% for the MS group and 6.5% for the control group. Authors noted that the SDMT, PASAT-2, and PASAT-3 scores were significantly lower in the MS group compared with the control group (P <.001; P = .001, and P <.001, respectively). Additionally, the interaction effect of MS and SAS on cognitive function was not significant for the SDMT (P = .078) but was significant for the PASAT-2 (P = .043) and PASAT-3 (P = .020).

“Our study revealed significant trends for scores of cognitive tests such as the SDMT, PASAT-2, PASAT-3, and MMSE among the control group, the MS with REI less than 5 group, and the MS with REI at least 5 group. Post-hoc multiple comparisons after ANOVA also showed cognitive decline in people living with MS even whether with or without SAS, which was characterized with attention and concentration,” Maeda et al noted.1 “The analysis of the interaction effects of MS and SAS on cognitive function suggested a statistical association between concomitant SAS and decline of cognitive functions in people living with MS.”

All told, limitations of the study included that a type III portable monitor was used for OCST and could not monitor the sleep stage for the participants. Since BMI were statistically different between the control and MS groups, authors adjusted it throughout the study as a confounding factor for the statistical analysis which might have impacted the results. Notably, the findings of prevalence rates of OSA in Japanese patients with MS excludes diagnosed patients with OSA at start of recruitment.

“In this study, sleep quality was significantly lower in people living with MS than controls. However, the trend analysis showed no significance among the control group, the MS without SAS group, and the MS with SAS,” Maeda et al noted.1 “Post-hoc analysis also showed no difference between any 2 of the 3 groups. Depression was not detected in both controls and people living with MS either with or without SAS, whereas a significant trend for apathy was detected among the control group, the MS without SAS group, and the MS with SAS group.”

1. Terauchi T, Mizuno M, Suzuki M, et al. Clinical features of sleep apnea syndrome and cognitive impairment in multiple sclerosis. Mult Scler Relat Disord. Published online December 23, 2023. doi:10.1016/j.msard.2023.105407
2. Makhani N, Tremlett H. The multiple sclerosis prodrome. Nat Rev Neurol. 2021;17(8):515-521. doi:10.1038/s41582-021-00519-3
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