Poor quality sleep may increase dementia risk

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Getting a good night’s sleep could be the key to improving memory in later life, a Daily Mail report says new research suggests. People who manage fewer than four hours a night or who wake regularly are more at risk of developing dementia. Poor quality sleep and restless nights are thought to trigger the formation of plaques on the brain linked to Alzheimer’s disease (AD).

The report says previous studies have shown disrupted sleep is common in people with the condition and could play a role in developing the disease. New research shows sleeping well could prevent the development of plaques – abnormal clusters of protein fragments – associated with Alzheimer’s. It is also thought to play a key role in maintaining grey matter health in regions of the brain sensitive to ageing and memory.

People who sleep poorly are more likely to have a build-up of amyloid-beta (Ab) – a sticky protein which clumps together to form damaging plaques, the study found. It claims length and quality of sleep is directly linked to these deposits on the brain.

Lead author Pierre Branger, of the University of Caen Normandy, France, is quoted in the report as saying that a good sleep could be pivotal to brain health in later life. He said in the report: “Our results indicate that poor sleep quality in older, asymptomatic individuals is associated with greater Ab burden and lower brain volume in brain areas known to be sensitive to ageing and AD processes.

“Sleep may, therefore, play a role in protecting against age and AD-related brain changes.

“This study highlights the potential relevance of preserving sleep quality in older adults and suggests that sleep may also be a critical factor to explore in individuals at risk for AD.”

The report says sleeping habits of around 50 volunteers, all over the age of 40, were analysed before quality of sleep was rated on a scale of one to six. General sleeping time was taken into account as was frequency of waking and overall quality of sleep over a five-year period. MRI scans were taken of the brain to uncover the presence of Ab plaques and activity of grey matter along with memory tests.

Researchers found poor sleeping habits were linked to development of Ab plaques with those who woke frequently during the night showing lower grey matter volume, the report said. Poor sleep was linked to greater Ab deposits on the brain suggesting it may “have a direct impact on brain structure”.

Branger said: “Poor self-reported sleep quality tends to have a greater impact on brain volume determined by structural MRI and Ab deposition.

“Our findings are in line with growing evidence from cognitively normal older adults that modifiable lifestyle factors may have an impact on AD biomarkers.

“In addition, chronic sleep restriction (four hours of sleep per night) for 21 days significantly increased Ab deposition in multiple brain areas.

“Further studies are needed to better understand the effect of the interaction between sleep on AD biomarkers.”

Abstract
Recent studies in mouse models of Alzheimer’s disease (AD) and in humans suggest that sleep disruption and amyloid-beta (Aβ) accumulation are interrelated, and may, thus, exacerbate each other. We investigated the association between self-reported sleep variables and neuroimaging data in 51 healthy older adults. Participants completed a questionnaire assessing sleep quality and quantity and underwent positron emission tomography scans using [18F]florbetapir and [18F]fluorodeoxyglucose and an magnetic resonance imaging scan to measure Aβ burden, hypometabolism, and atrophy, respectively. Longer sleep latency was associated with greater Aβ burden in prefrontal areas. Moreover, the number of nocturnal awakenings was negatively correlated with gray matter volume in the insular region. In asymptomatic middle-aged and older adults, lower self-reported sleep quality was associated with greater Aβ burden and lower volume in brain areas relevant in aging and AD, but not with glucose metabolism. These results highlight the potential relevance of preserving sleep quality in older adults and suggest that sleep may be a factor to screen for in individuals at risk for AD.

Full Daily Mail report
Neurobiology of Aging abstract


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