A new study published online this week in the American Heart Association’s journal Stroke suggests that disturbed sleep with frequent waking up in the elderly could be a sign that they are at greater risk of a stroke or impaired thinking and memory as poor sleeping is associated with more severe arteriosclerosis in the brain which can contribute to the risk of stroke and cognitive impairment.
The investigation, which was a collaboration between Rush University’s Alzheimers Disease Center and the Department of Neurological Sciences in Chicago and The National Institutes of Health, Canada’s Heart and Stroke Foundation, and the Canadian Institutes of Health Research in Toronto examined the autopsied brains of 315 people who had undergone at least one full week of sleep quality valuation before their death.
The results showed that 29% of them had suffered a stroke, and 61% had moderate-to-severe damage to blood vessels in the brain. Furthermore, researchers found that greater sleep fragmentation was associated with 27% higher odds of having severe arteriosclerosis and 30% increase in the odds that subjects had visible signs of oxygen deprivation in their brain for each additional two arousals during one hour of sleep.
“Although based on this study alone, we cannot know for sure that sleep fragmentation contributes to brain blood-vessel damage and infarct pathology as opposed to vice versa, our data are consistent with this hypothesis and add to the growing body of evidence suggesting that sleep quality is linked to brain injury in older persons,” study author Andrew Lim, MD, of Sunnybrook Health Sciences Center said.
Lim also pointed out that the forms of brain injury they observed in the study may not only contribute to the risk of stroke but also to chronic progressive cognitive and motor impairment.
According to the authors, there are 3 possible explanations for the findings: cerebrovascular pathology causes sleep fragmentation, sleep disruption causes brain injury, or an unmeasured variable influences to both.
They explained the hypothalamus and other sleep centers represent a tiny volume of the brain and hypothalamic infarction is unusual because of its rich blood supply although individuals with clinical stroke symptoms should be the most likely to have stroke-induced sleep fragmentation, the associations were independent of clinically evident stroke.
On the other hand, for the possibility that sleep fragmentation causes brain injury, the authors argued that other forms of sleep disruption are associated with physiological risk factors for cerebrovascular pathology, including diurnal and nocturnal hypertension and abnormal glucose processing, among others.
Even though further work is needed to determinate if these are consequences or causes of sleep fragmentation, these results may indicate that sleep monitoring may potentially be another way to identify seniors who may be at risk of stroke.