Dementia signs: How you sleep could be increasing your risk of the condition developing
Dementia is an umbrella term used to describe a range of progressive diseases that affect the brain. There are four main types – Alzheimer’s disease, lewy body dementia, vascular dementia and frontotemporal dementia. While the exact cause of dementia is unknown, a new study has suggested day naps could mean you’re more at risk of the condition developing.
Scientists in the research found those who like a daytime snooze tended to have more tau proteins that form tangles in the brain, causing dementia – tau proteins are proteins found in neutrons of the central nervous system.
They also found a lack of deep sleep fuels rogue proteins in the brain that destroy neutrons, say scientists.
The study of more than 100 older people found those not getting enough “quality” shut-eye also had more tau, leading to memory loss and confusion.
It could lead to nocturnal habits being monitored to help identify patients most at risk of the devastating condition.
In particular it is deep, restorative slow wave sleep (SWS) that is essential. This declines naturally as we age – in men from their mid 30s and women during their 50s.
First author Professor Brendan Lucey, director of the Washington University Sleep Medicine Centre in St Louis, said: “The key is it wasn’t the total amount of sleep that was linked to tau.
“It was the slow-wave sleep – which reflects quality of sleep. The people with increased tau were actually sleeping more at night and napping more in the day – but they weren’t getting as good quality sleep.”
The finding published in Science Translational Medicine adds to a growing body of evidence linking poor sleep to Alzheimer’s and other forms of dementia.
Daytime napping alone was significantly associated with high levels of tau.
It means doctors could identify patients who could benefit from further testing simply by asking ‘how much do you nap during the day?’.
Last year a similar study by another US team found those who napped during the day – when they should have been awake – had almost three times as much amyloid beta. This is another damaging protein that can trigger dementia by clumping together in grey matter and forming plaques.
Prof Lucey said fewer slow brain waves that occur during the most refreshing part of the sleep cycle is associated with high levels of the other toxic brain protein tau.
He said: “What’s interesting is we saw this inverse relationship between decreased slow-wave sleep and more tau protein in people who were either cognitively normal or very mildly impaired – meaning reduced slow-wave activity may be a marker for the transition between normal and impaired.
“Measuring how people sleep may be a non-invasive way to screen for Alzheimer’s disease before or just as people begin to develop problems with memory and thinking.”
Poor sleep is a hallmark of Alzheimer’s. People with the disease tend to wake up tired – and their nights become even less refreshing as memory loss and other symptoms worsen.
But the connections between restless nights and Alzheimer’s are not fully understood. Prof Lucey and colleagues believe they have uncovered part of the explanation.
Participants who had less SWS – that consolidates an memories and leaves us waking up feeling refreshed – had more tau.
This is a sign of Alzheimer’s and has been linked to brain damage and cognitive decline.
It suggests poor-quality sleep in later life could be a red flag for deteriorating brain health, said Prof Lucey.