- Obstructive sleep apnea, the most common type of sleep breathing disorder, is a risk factorfor cerebrovascular disease, conditions that affect blood vessels in the brain.
- Obstructive sleep apnea is also linked to mild cognitive impairment and Alzheimer’s disease, but the mechanisms underlying this association are not well understood.
- Dementia is also associated with abnormalities in the brain’s white matter that are hallmarks or markers of cerebrovascular diseases.
- A recent observational study shows that severe obstructive sleep apnea and reduced deep sleep were independently associated with white matter abnormalities related to cerebrovascular diseases in cognitively unimpaired older adults.
- These findings show that severe obstructive sleep apnea and poor sleep quality can lead to an increase in the biomarkers of cerebrovascular disease, potentially increasing the risk of cognitive decline and stroke.
Obstructive sleep apnea is the most common type of sleep-breathing disorder that affects nearly a billion individuals across the globe.
A recent study published in Neurology suggests that obstructive sleep apnea and a reduction in deep sleep, also known as slow-wave sleep, were independently associated with an increase in white matter abnormalities in the brain.
The white matter abnormalities assessed in the study are known markers of cerebrovascular disease and are also observed in mild cognitive impairment and Alzheimer’s disease.
The findings from this observational study thus suggest that obstructive sleep apnea and poor sleep quality could potentially lead to increased white matter abnormalities, subsequently increasing the risk of dementia and stroke.
The study’s author Dr. Diego Carvalho, a neurologist at the Mayo Clinic in Rochester, MN, told Medical News Today:
“White matter abnormalities increase with aging and may contribute to cognitive decline, dementia, and stroke. Since there is no treatment to reverse or slow them down other than risk factor prevention, it is important to understand what may contribute to their development.”
“In our study, we found that severe sleep apnea and decreased deep sleep were associated with more white matter abnormalities. Although we cannot infer a direct causal relationship with a cross-sectional study design, the findings raise the possibility that sleep interventions may prevent the progression of white matter disease. Although there is already compelling evidence that sleep apnea is involved in white matter abnormalities, the potential role of slow-wave sleep (or deep sleep) in white matter health is much less understood,” added Dr. Carvalho.
Sleep quality and dementia
Obstructive sleep apnea is a sleep-breathing disorder characterized by episodes of interruption of breathing due to partial or complete blockage of the upper airway. The episodes of reduced breathing are known as hypopnea, whereas apnea refers to events involving a complete blockage of the upper airway.
The apnea-hypopnea index (AHI) describes the number of apnea and hypopnea events per hour. Specifically, obstructive sleep apnea involves at least five such episodes of apnea or hypopnea per hour.
The interruption of breathing triggers a compensatory response that leads to arousal from sleep. Thus, obstructive sleep apnea leads to sleep disturbances and an experience of feeling unrefreshed after sleep.
Several studies have shown that poor sleep quality is associated with an increased risk of cognitive decline and dementia.
The accumulation of misfolded deposits of the amyloid-beta and tau proteins is a hallmark of Alzheimer’s disease. A previous study showed a higher accumulation of the amyloid-beta protein in the brains of individuals experiencing excessive daytime sleepiness.
In contrast, a brain imaging study showed that cognitively unimpaired individuals with higher tau levels in their brains were at an increased risk of obstructive sleep apnea.
These studies suggest a bidirectional relationship between sleep quality and pathological changes associated with Alzheimer’s disease.
