Individuals with hypertension and short sleep duration may be at high risk for cognitive impairment and vascular brain injury. The results show that in individuals with hypertension, shorter sleep duration was associated with poorer executive functioning, increased white matter hyperintensities, and gray matter atrophy on brain MRI; these same associations were not observed in individuals with normal blood pressure.
Insufficient sleep has become a growing public health problem, with up to half of adults in the United States sleeping less than the recommended seven hours per night. This lack of sleep can seriously harm the brain, as both excessively short and excessively long sleep are associated with cognitive decline and an increased risk of dementia.
Therefore, better understanding the mechanisms behind inadequate sleep, especially early in the pathological processes that lead to diseases such as dementia, is a priority in health research.
One theory that has gained traction is that sleep dysfunction may impair the brain’s ability to clear neurotoxic proteins, such as amyloid beta (Aβ), which has been linked to the development of Alzheimer’s disease.
While poor sleep directly impairs the brain’s clearance of these substances, it may also increase the risk of dementia through other factors, such as hypertension (high blood pressure), which is often associated with short sleep duration.
High blood pressure, in particular, is considered a major risk factor for cognitive problems and dementia later in life. Research shows that high blood pressure can affect areas of the brain responsible for attention and executive functions, such as planning and decision-making.
This effect occurs because high blood pressure is associated with damage to the brain’s small blood vessels, which can cause damage to the white matter, the part of the brain responsible for communication between different areas. In addition, high blood pressure can disrupt brain circuits that control important cognitive functions.
Sleep also has a direct impact on blood pressure. During sleep, blood pressure tends to decrease by about 10%, which is a natural and healthy phenomenon.
However, lack of sleep can disrupt this reduction in blood pressure, resulting in high blood pressure that may be masked (not noticeable) during the night.
When high blood pressure is combined with lack of sleep, it can further increase the risk of cardiovascular problems, such as heart attacks and strokes. However, the interaction between these two factors, high blood pressure and poor sleep, has not yet been sufficiently studied with regard to cognitive health and its impact on the brain.
Researchers at Monash University in Australia conducted a study to investigate how hypertension might influence the relationship between sleep duration and cognitive performance, as well as its effects on the brain, such as accelerated aging and brain damage.
To do this, they analyzed a sample of 682 people who participated in the Framingham Heart Study, a long-term study of cardiovascular health. These participants, who had an average age of 62, underwent assessments of cognition, blood pressure, and sleep patterns.
In addition, 637 people underwent MRI scans to assess brain damage. The researchers wanted to test the hypothesis that people with shorter sleep would have worse performance on executive function tasks, such as quick reasoning and decision-making, and more damage to the white matter of the brain, especially those with hypertension.
The analyses showed that, indeed, people with hypertension and short sleep had worse cognitive performance and more lesions in the white matter of the brain, such as hyperintensities (areas of damage), compared to people with normal blood pressure.
In addition, the results showed that longer sleep duration was associated with better scores on cognitive tasks for the group of people with hypertension, indicating that longer sleep may help improve brain function in these people. However, this was not observed in people with normal blood pressure, suggesting that hypertension may be a factor that worsens the impact of insufficient sleep.
Finally, this study suggests that individuals with hypertension and insufficient sleep may be a high-risk group for cognitive impairment and brain damage. Early detection of sleep problems in people with hypertension may help to create personalized treatments to improve brain health and prevent accelerated brain aging.
The research also points to the need for new clinical trials to test sleep and blood pressure-lowering therapies, which may help prevent or delay the development of cognitive problems, such as dementia.
READ MORE:
Short Sleep Duration and Hypertension: A Double Hit for the Brain
Stephanie Yiallourou, Andree-Ann Baril, Crystal Wiedner, Xuemei Song,
Rebecca Bernal, Dibya Himali, Marina G. Cavuoto, Charles DeCarli,
Alexa Beiser, Sudha Seshadri, Jayandra J. Himali, and Matthew P. Pase
Journal of the American Heart Association. Volume 13, Number 21
Abstract:
Short sleep duration has been associated with an increased risk of cognitive impairment and dementia. Short sleep is associated with elevated blood pressure, yet the combined insult of short sleep and hypertension on brain health remains unclear. We assessed whether the association of sleep duration with cognition and vascular brain injury was moderated by hypertensive status.
A total of 682 dementia‐free participants (mean age, 62±9 years; 53% women) from the Framingham Heart Study completed assessments of cognition, office blood pressure, and self‐reported habitual and polysomnography‐derived sleep duration; 637 underwent brain magnetic resonance imaging. Linear regressions were performed to assess effect modification by hypertensive status on total sleep time (coded in hours) and cognitive and magnetic resonance imaging outcomes. There was a significant interaction between sleep duration and hypertensive status when predicting executive function/processing speed (Trail Making B‐A) and white matter hyperintensities. When results were stratified by hypertensive status, longer sleep duration was associated with better executive functioning/processing speed scores in the hypertensive group (meaning that shorter sleep duration was associated with poorer executive function/processing speed scores) (self‐report sleep: β=0.041 [95% CI, 0.012–0.069], P=0.005; polysomnography sleep: β=0.045 [95% CI, 0.002–0.087], P=0.038), but no association was observed for the normotensive group. Similarly, shorter subjective sleep duration was associated with higher white matter hyperintensity burden in the hypertensive group (β=−0.115 [95% CI, −0.227 to −0.004], P=0.042), but not in the normotensive group. In individuals with hypertension, shorter sleep duration was associated with worse cognitive performance and greater brain injury.
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