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Poor sleep linked to hardened blood vessels, small strokes in seniors

Jan 14, 2016

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A Sunnybrook-led study suggests that elderly people who sleep poorly and awaken frequently are more likely to have hardened blood vessels or small strokes in the brain, both of which can contribute to cognitive and motor impairment.

Published in the journal Stroke, the study is the first to conduct a detailed examination of blood vessels from autopsied brains of seniors who had undergone sleep monitoring before death.

The researchers found that greater sleep fragmentation was associated with 27 per cent higher odds of having severe arteriosclerosis. For each additional two arousals during one hour of sleep, they reported a 30 per cent increase in the odds that subjects had visible signs of oxygen deprivation (infarcts) in their brain.

Fragmented sleep occurs when sleep is interrupted by repeated awakenings or arousals. In this study, sleep was disrupted on average almost seven times each hour.

“The pathologies that we observed are important because they may not only contribute to the risk of stroke but also to chronic progressive cognitive and motor impairment,” said Dr. Andrew Lim, lead investigator of the study and a neurologist at Sunnybrook.

This is the first study to look specifically for an association between objectively quantified sleep fragmentation and detailed microscopic measures of blood vessel damage and infarcts in autopsied brain tissue from the same individuals.

“There are several ways to view these findings: Sleep fragmentation may impair the circulation of blood to the brain, poor circulation of blood to the brain may cause sleep fragmentation, or both may be caused by another underlying risk factor,” said Dr. Lim.

The findings suggest that sleep monitoring may potentially be another way to identify seniors who may be at risk of stroke, but further work is needed to clarify whether brain blood vessel damage is a consequence or cause of sleep fragmentation, the role of specific contributors to sleep fragmentation such as sleep apnea, and the underlying biological mechanisms.

View a plain-text version of the infographic

Sleep & Stroke

Researchers examined the blood vessels from autopsied brains of seniors who had undergone sleep monitoring before death.

The links they found are providing important clues about brain health and disease.

Elderly people who sleep poorly have an increased risk of:

  • Hardened arteries
    • 27%
or
  • small strokes
    • 30% for each additional 2 arousals per hour of sleep

Which may have contributed to their risk of:

  • stroke
  • cognitive and motor impairment

Sleep monitoring

another potential way to help identify seniors who may be at risk of stroke

Dr. Andrew Lim

Full media release

TORONTO (January 14, 2015) – A Sunnybrook-led study suggests that elderly people who sleep poorly and awaken frequently are more likely to have hardened blood vessels or small strokes in the brain, both of which can contribute to cognitive and motor impairment.

Published in the January 2016 issue of Stroke, a journal of the American Heart Association, the study is the first to conduct a detailed examination of blood vessels from autopsied brains of seniors who had undergone sleep monitoring before death.

The researchers found that greater sleep fragmentation was associated with 27 percent higher odds of having severe arteriosclerosis. For each additional two arousals during one hour of sleep, they reported a 30 percent increase in the odds that subjects had visible signs of oxygen deprivation (infarcts) in their brain.

Fragmented sleep occurs when sleep is interrupted by repeated awakenings or arousals. In this study, sleep was disrupted on average almost seven times each hour.

“The pathologies that we observed are important because they may not only contribute to the risk of stroke but also to chronic progressive cognitive and motor impairment,” said Dr. Andrew Lim, lead investigator of the study and a neurologist at Sunnybrook Health Sciences Centre.

The relationship between cardiovascular disease and so-called “fragmented” sleep has been studied in the past, but this is the first study to look specifically for an association between objectively quantified sleep fragmentation and detailed microscopic measures of blood vessel damage and infarcts in autopsied brain tissue from the same individuals.

The researchers examined autopsied brains of 319 people (average age at death 90, 70 percent women) who had undergone at least one full week of around-the-clock monitoring for rest or activity, from which sleep quality and circadian rhythms were quantified. In all, 29 percent of the patients had suffered a stroke, while 61 percent had signs of moderate to severe damage to their blood vessels in the brain.

“There are several ways to view these findings: Sleep fragmentation may impair the circulation of blood to the brain, poor circulation of blood to the brain may cause sleep fragmentation, or both may be caused by another underlying risk factor,” said Dr. Lim, also an assistant professor of neurology at University of Toronto.

The findings suggest that sleep monitoring may potentially be another way to identify seniors who may be at risk of stroke, but further work is needed to clarify whether brain blood vessel damage is a consequences or cause of sleep fragmentation, the role of specific contributors to sleep fragmentation such as sleep apnea, and the underlying biological mechanisms.

This research is an example of how we’re making Ontarians Healthier, Wealthier and Smarter.

The co-authors of the study were Dr. Lei Yu, Dr. Julie Schneider, Dr. David Bennett, and Dr. Aron Buchman from the Rush Alzheimer’s Disease Centre.

The National Institutes of Health, Canada’s Heart and Stroke Foundation, and the Canadian Institutes of Health Research supported the study.

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Media contact:
Nadia Norcia Radovini, (416) 480-4040, nadia.radovini@sunnybrook.ca

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