Andrew S.P. Lim
Andrew S.P. Lim, MD, assistant professor of neurology at the University of Toronto and neurologist and scientist at Sunnybrook Health Sciences Center in Toronto and colleagues investigated the association between sleep fragmentation and microscopic measures of blood vessel damage and infarcts in autopsied brain tissue of 315 participants (70% women; mean age at death, 90 years) from the Rush Memory and Aging Project. All participants had undergone at least one full week of sleep monitoring before death. Average sleep disruption was seven times per hour.
Twenty-nine percent of the participants had a stroke, according to researchers. Sixty-one percent showed signs of moderate or severe damage to the blood vessels in the brain. Lim and colleagues observed that greater sleep fragmentation was associated with a 27% higher risk for severe arteriolosclerosis (OR = 1.27; 95% CI, 1.02-1.59) and a greater than 30% higher risk for subcortical macroscopic infarcts per each additional two arousals during 1 hour of sleep (OR = 1.31; 95% CI, 1.01-1.68), independent of CV risk factors and diseases. The researchers did not observe an association between clinically evident stroke and sleep fragmentation (OR = 0.95; 95% CI, 0.72-1.22).
This lack of association between stroke and sleep fragmentation, Lim explained to Cardiology Today is most likely because “only a subset of pathological infarcts manifests as acute stroke. Moreover, the quantification of infarcts is more objective than assessing for stroke clinically, and less prone to measurement error.”
“The forms of brain injury 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,” Lim, said in a press release.
“However, 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,” he said.
Results show that older adults with worse sleep fragmentation had a greater burden of brain arteriolosclerosis and infarct pathology at death. However, Lim and colleagues acknowledged limitations of this study, including the observational design and lack of measurement of sleep apnea and periodic limb movements.
“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,” Lim told Cardiology Today.
“Further studies are needed to investigate which forms of sleep fragmentation are most closely linked to cerebrovascular pathology, which will aid in developing clinical trials of interventions to prevent cerebrovascular pathology by improving sleep.”
In addition, Lim noted that “further studies in humans and animal models are also needed to better understand the physiological and cellular mechanisms linking sleep fragmentation to cerebrovascular health.” – by Tracey Romero
The researchers report no relevant financial disclosures.