A recent study suggests that sleep disorders, including insomnia, sleep apnea, and sleepiness, may contribute to self-reported cognitive decline in women with multiple sclerosis (MS). The study analyzed data from over 60,000 female nurses and found that those with sleep disorders, which are often linked to MS fatigue, tended to report worse cognitive function four years later.
The reported cognitive problems included difficulties in following instructions or conversations and navigating familiar streets. Identifying and treating sleep disorders could be crucial in addressing perceived cognitive decline, even in the absence of objective changes.
The study, titled “Pathways between multiple sclerosis, sleep disorders, and cognitive function: Longitudinal findings from The Nurses’ Health Study,” was published in the Multiple Sclerosis Journal. Tiffany Braley, MD, the director of the MS Fatigue and Sleep Clinic at the University of Michigan Health, led the study.
Researchers have undertaken a study to investigate the relationship between sleep disorders and cognitive dysfunction in women with multiple sclerosis (MS). Cognitive impairment is a prevalent and debilitating symptom in MS, affecting a significant portion of individuals with the disease. Current therapies for improving cognitive function in MS have limited effectiveness, prompting researchers to explore potential risk factors that could be targeted to alleviate these symptoms.
Sleep disorders are more prevalent in individuals with MS compared to the general population and have been linked to cognitive difficulties and decreased quality of life. However, previous studies primarily focused on objective measures of cognition and did not specifically address perceived changes in cognitive processes. Additionally, the interaction between MS and sleep disorders in exacerbating cognitive impairment has not been adequately examined.
Dr. Tiffany Braley, who serves as the director of the division of multiple sclerosis and neuroimmunology at University of Michigan Health, emphasized the need to understand the interaction between sleep and MS in impacting long-term cognitive outcomes. Previous research has identified connections between objective cognitive performance and sleep in individuals with MS. However, the specific relationship between sleep problems and perceived cognitive changes has not been extensively studied.
To investigate whether sleep problems mediate perceived cognitive changes in women with MS, the researchers analyzed data from over 63,000 female nurses, including 524 who had been diagnosed with MS. These participants are part of the Nurses’ Health Study II, a comprehensive long-term study focused on identifying risk factors for chronic diseases in women.
The analysis included participants who had completed comprehensive questionnaires in both 2013 and 2017. These questionnaires covered various aspects, including sleep patterns, cognitive function, and other clinical factors and lifestyle habits, aiming to gather detailed information.
On average, the participants were 58.7 years old in 2013. Among the nurses included in the study, those with MS had a higher prevalence of various sleep disorders compared to those without MS. These sleep disorders included obstructive sleep apnea (OSA), which involves repeated breathing interruptions during sleep, as well as insomnia and excessive daytime sleepiness.
In the 2017 questionnaire, cognitive function was assessed using specific questions related to memory and three other aspects of cognition. These aspects included difficulties in understanding or following spoken instructions, recent challenges in following group conversations or understanding the plot of a television program, and trouble navigating familiar routes or places.
Irrespective of sleep issues, individuals with MS were found to be 2.2 times more likely to experience difficulties in following spoken instructions compared to those without MS. They were also 1.9 times more likely to have trouble following conversations or understanding plots, and had a 2.7 times higher likelihood of experiencing challenges in navigating familiar streets.
However, the impact of MS on cognitive function was partially influenced by sleep problems reported by the nurses in 2013. Insomnia, for instance, accounted for 5.4% of the total effect of MS on the ability to follow spoken instructions, 8.4% on the ability to follow conversations or plots, and 15.1% on memory problems.
In the case of sleepiness, the mediating effect was even more significant. Sleepiness mediated 8.6% of the total effect of MS on the ability to follow spoken instructions, 10.1% on the ability to follow conversations or plots, and 12.3% on memory difficulties.
Obstructive sleep apnea (OSA) was responsible for 34% of the total effect of MS on the ability to follow spoken instructions but did not have a significant impact on other measures of cognition.
The researchers found that obstructive sleep apnea (OSA), insomnia symptoms, and sleepiness may have varying effects on how multiple sclerosis (MS) impacts perceived cognition in women with MS. These sleep disorders are associated with distinct direct and indirect relationships with cognitive function.
Furthermore, the study suggests that early identification of cognitive symptoms, such as through patient self-reporting, could facilitate the initiation of potential therapies at an early stage. The researchers stated that interventions aimed at delaying cognitive decline in MS may be most effective when administered during the pre-symptomatic or early symptomatic stages.
In conclusion, the findings emphasize that sleep disorders are common contributors to cognitive dysfunction in women with MS and highlight their potential for modification through intervention.
