Objectives: It is estimated that up to 65% of pwMS (people with multiple sclerosis) experience varying degrees of cognitive impairment, the most commonly affected domain being information processing speed (IPS). As sleep disturbance is a predictor of detriments in IPS, we aimed to study the association between severity of restless leg syndrome (RLS) and obstructive sleep apnea (OSA) symptoms with IPS in pwMS using a language and education independent tool.
Methods: In a cross-sectional study, we enrolled pwMS referred to multiple sclerosis comprehensive center of Kashani hospital in Isfahan, Iran. We used Berlin and STOP-Bang questionnaires for assessing OSA symptom severity. The International Restless Legs Syndrome Study Group scale was utilized for determining presence and severity of symptoms of restless leg syndrome. We used Integrated Cognitive Assessment (ICA) test assess visual processing speed.
Results: We included 211 pwMS, with a mean age of 36.88±8.76 (82.9% female). There were significant association between RLS symptoms severity and ICA index (p=0.00), but there is no association between ICA index and OSA symptom severity using STOP-Bang scale (ICA index of 0.61±0.14 and 0.60±0.08 in low and high-risk pwMS respectively; p=0.897) and Berlin scale (ICA index of 0.61±0.14 and 0.59±0.15 in low and high-risk pwMS, respectively; p=0.384).
Conclusion: We found that the severity of RLS in patients with MS can worsen information processing speed, but sleep apnea did not show any effect on this domain of cognitive dysfunction.