Poor sleep in MS linked to slower removal of brain waste

People with multiple sclerosis (MS) who report difficulty sleeping tend to have reduced flow in what essentially serves as the body’s biological sewer system for removing waste from the brain, a new study suggests.

The findings imply that getting a good night’s sleep may meaningfully affect brain biology in MS. And, given that medications and other interventions are available to help people sleep better, the researchers called for further studies to investigate whether boosting sleep might meaningfully improve clinical outcomes or markers of disease biology in MS.

“Whether sleep-targeted interventions can modify [markers of waste removal in the brain] or downstream clinical and MRI outcomes remains unknown and should be tested in longitudinal interventional studies,” the scientists wrote, noting that “sleep disturbances” in people with MS were “independent of clinical disability.”

The study, “Subjective sleep disturbances are associated with reduced MRI-derived perivascular-space diffusivity in multiple sclerosis,” was published in the Journal of Neurology by researchers in Italy.

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A neurological disorder, MS is marked by symptoms that can include mobility limitations, fatigue, and cognitive impairment. Many people with MS experience difficulty getting a good night’s sleep. The researchers noted that sleep disturbances “are associated with fatigue, mood symptoms, cognitive impairment, and reduced quality of life, and may represent modifiable contributors to clinical burden in MS.”

Researchers call for early interventions for poor sleep

Within the brain, fluid is constantly flowing to provide nutrients to nerve cells and to carry away molecular debris. This flow of fluid is known as the glymphatic system; it is often analogized as the brain’s plumbing or sewer system. Previous studies have suggested that poor sleep can lead to slowed glymphatic flow — in other words, without enough sleep, the brain’s sewers start backing up and waste is not removed.

“Although these data mainly derive from non-MS settings, they support investigating whether poor sleep quality is associated with altered brain-fluid markers in MS,” the researchers wrote.

To look into this association, the research team analyzed data from 77 people with MS and 84 age- and sex-matched healthy individuals, who served as controls. All of the patients underwent MRI scans and completed several standardized questionnaires, including the Pittsburgh Sleep Quality Index (PSQI), an assessment in which people subjectively rate how well they have slept recently.

The researchers used statistical analyses to look for MRI markers that were significantly associated with PSQI scores. Only one was found: Patients with higher PSQIs, reflecting worse sleep, tended to have lower DTI-ALPS, an MRI measure that indirectly reflects the flow of fluid through the glymphatic system.

“The novel contribution of this study is the demonstration that subjective sleep disturbances are associated with a lower DTI-ALPS index within MS, even when clinical and structural MRI measures are comparable between sleep subgroups,” the researchers wrote.

Early identification and management of poor sleep quality may improve fatigue, mood symptoms, cognition, and quality of life.

In comparisons against MRI data from the controls, the researchers noted that DTI-ALPS was generally lower among the MS patients, irrespective of sleep problems. This aligns with prior studies suggesting that glymphatic flow may be slowed in neurological diseases, the team noted.

“Our observation of a lower DTI-ALPS index in MS patients compared with [healthy controls] is in line with previous adult and pediatric MS studies,” the scientists wrote. “Thus, the present findings confirm that DTI-ALPS abnormalities are part of the broader spectrum of MRI-detectable tissue and brain-fluid alterations in MS.”

Based on these findings, the researchers speculated that sleep may alter the flow of the brain’s sewer-like system in MS. If that’s true, it may be possible to modulate disease biology through interventions aimed at improving sleep, according to the team.

Still, the researchers stressed that more research is needed to investigate these hypotheses. In the meantime, the team emphasized the importance of addressing poor sleep for MS patients’ overall well-being.

“Sleep disturbances are common in MS and may be at least partly modifiable through behavioral, pharmacologic, and disorder-specific interventions,” the team wrote, adding that “early identification and management of poor sleep quality may improve fatigue, mood symptoms, cognition, and quality of life.”