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Poor sleep linked with enlarged spaces around brainís blood vessels

May 29, 2015

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Sleep may play an important role in clearing waste and toxins from the brain, the study finds

Sunnybrook brain scientists have demonstrated for the first time in humans that poor sleep quality is linked with enlarged spaces in the brain thought to be tasked with toxin removal.

“Sleep may play an important role in clearing waste and toxins in the brain, which in turn may contribute to the development of brain diseases,” says Dr. Mark Boulos, stroke and sleep neurologist in the Hurvitz Brain Sciences Program at Sunnybrook, and the principal investigator of a new study.

“This could be particularly important for patients suffering from stroke or dementias such as Alzheimer’s disease that are thought to arise from the buildup of toxins in the brain, as sleep may be an important factor in their development.”

Unlike other organs in the body, the brain does not have a dedicated lymphatic waste removal system. Instead, it uses fluid-filled channels called perivascular Virchow-Robin spaces that surround the brain’s blood vessels to drain toxins and waste products away.

“It was previously shown that patients with stroke tend to have a larger number of these enlarged spaces around their brains’ blood vessels compared to people without stroke, suggesting blockage of these waste removal channels,” says Dr. Joel Ramirez, co-lead author for the study and Post-Doctoral Fellow, Heart & Stroke Foundation Canadian Partnership for Stroke Recovery - Sunnybrook site.

Because the brain doesn’t have anywhere else to rid itself of its toxins, the researchers suspect these spaces (channels) act as drainage systems that can be susceptible to a build up of toxins, and become blocked and enlarged as a result.

“In those with poor quality sleep, the perivascular spaces (seen as dark spots on 3D MRI brain scans) were more frequent than those with healthy sleep patterns,” says Courtney Berezuk, first author of the study and a Neuroimaging Analyst in Dr. Sandra Black’s L.C. Campbell Cognitive Neurology Research Unit at Sunnybrook.

"Since many sleep disorders that give rise to sleep fragmentation are readily treatable, this research holds the promise of providing a novel therapeutic option for patients living with the effects of stroke or other brain diseases,” says Boulos.

For otherwise healthy individuals: “If you have a sleep problem, see your doctor about improving your quality of sleep as there are many treatment options out there. Don’t just attribute poor sleep to your age or underlying health condition, it’s good to have it checked out because over the years it could have implications for your overall health.”

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Poor sleep linked with enlarged spaces around the brain’s blood vessels

May 29, 2015 (Toronto, ON) – Sunnybrook brain scientists have demonstrated for the first time in humans that poor sleep quality is linked with enlarged spaces in the brain thought to be tasked with toxin removal.

“Sleep may play an important role in clearing waste and toxins in the brain, which in turn may contribute to the development of brain diseases,” says Dr. Mark Boulos, a stroke and sleep neurologist in the Hurvitz Brain Sciences Program at Sunnybrook Health Sciences Centre, and the principal investigator of a new study published as the lead paper in the June 1, 2015 issue of the journal SLEEP. “This could be particularly important for patients suffering from stroke or dementias such as Alzheimer’s disease that are thought to arise from the buildup of toxins in the brain, as sleep may be an important factor in their development.”

Unlike other organs in the body, the brain does not have a dedicated lymphatic waste removal system. Instead, it uses fluid-filled channels called perivascular Virchow-Robin spaces (VRS) that surround the brain’s blood vessels to drain toxins and waste products away.

“It was previously shown that patients with stroke tend to have a larger number of these

enlarged spaces around their brains’ blood vessels compared to people without stroke, suggesting blockage of these waste removal channels,” says Dr. Joel Ramirez, co-lead author for the study and Post-Doctoral Fellow, Heart & Stroke Foundation Canadian Partnership for Stroke Recovery - Sunnybrook site.

Because the brain doesn’t have anywhere else to rid itself of its toxins, the researchers suspect these spaces (channels) act as drainage systems that can be susceptible to a build up of toxins, and become blocked and enlarged as a result.

The research team set out to examine the MRI brain scans and sleep study test results of 26 patients who had suffered either a stroke or a transient ischemic attack (TIA).

“We looked at the volume of perivascular spaces on their MRI scans and correlated them with markers of sleep fragmentation from their sleep studies,” says Courtney Berezuk, first author of the study and a Neuroimaging Analyst in Dr. Sandra Black’s L.C. Campbell Cognitive Neurology Research Unit at Sunnybrook. “In those with poor quality sleep, the perivascular spaces (seen as dark spots on 3D MRI brain scans) were more frequent than those with healthy sleep patterns.”

The researchers say this supports previous work showing that chronically poor sleep is bad for one’s health and a potential risk for disease, and call for further study to provide a better understanding of how the brain clears neurotoxins and its relationship with the restorative effects of sleep. “Since many sleep disorders that give rise to sleep fragmentation are readily treatable, this research holds the promise of providing a novel therapeutic option for patients living with the effects of stroke or other brain diseases,” says Boulos.

For otherwise healthy individuals, the take-home message for now is: “If you have a sleep problem, see your doctor about improving your quality of sleep as there are many treatment options out there. Don’t just attribute poor sleep to your age or underlying health condition, it’s good to have it checked out because over the years it could have implications for your overall health.”

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Media Contact:

Nadia Norcia Radovini

Sunnybrook Health Sciences Centre

416.480.4040

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