Being a loud snorer could cause dementia, warns a new study.
Scans have found people with the common bedtime disorder sleep apnoea have higher amounts of a rogue brain protein that causes Alzheimer’s disease.
The findings add to a growing body of evidence that getting plenty of good quality shut eye protects against dementia. Heavy snorers are up to three times more prone.
An estimated 1.5 million people in the UK suffer from it – and many will never have been formally diagnosed.
Scientists found those whose partners witnessed them having episodes of apnoea had more tau in grey matter linked to memory.
In Alzheimer’s, the chemical forms into tangles that kill neurons – leading to confusion and other symptoms of cognitive decline.
Study author Dr Diego Carvalho, of the Mayo Clinic in the United States, said: “A person normally has fewer than five episodes of apnoea per hour during sleep.
“Bed partners are more likely to notice these episodes when people stop breathing several times per hour during sleep, raising concern for obstructive sleep apnoea.
“Recent research has linked sleep apnoea to an increased risk of dementia, so our study sought to investigate whether witnessed apnoeas during sleep may be linked to tau protein deposition in the brain.”
His finding was based on 288 people aged 65 and older who did not have cognitive impairment.
Their partners were asked whether they had witnessed breathing stops during sleep – which triggers snoring.
Obstructive sleep apnoea involves frequent such events, although single episodes can also occur.
Afterwards, the participants had PET (positron emission tomography) scans to look for accumulation of tau tangles in the entorhinal cortex.
This is an area of the brain in the temporal lobe that is more likely to accumulate them. It helps manage memory, navigation and perception of time.
The researchers identified 43 of the volunteers – 15 percent of the group – whose bed partners witnessed apnoeas when they were sleeping.
They had an average 4.5 percent more tau than those who did not have apnoeas. This was after taking into account other factors that could affect levels including age, sex, education, cardiovascular disease risk and other sleep complaints.
Dr Carvalho said: “Our research results raise the possibility sleep apnoea affects tau accumulation.
“But it is also possible higher levels of tau in other regions may predispose a person to sleep apnoea, so longer studies are now needed to solve this chicken and egg problem.”
The preliminary finding will be presented at an American Academy of Neurology meeting in Philadelphia in May. Dr Carvalho called for larger studies to confirm his result.
Sleep apnoea causes the airways to become obstructed. It is the most common sleep related breathing disorder suffered in adults.
Twice as common in men as in women, the symptoms are often noticed first by a partner. It can be treated by wearing a mask in bed that blows air into the back of the throat.
Alzheimer’s and other forms of dementia affects 850,000 people in the UK alone, a figure set to rise to 2 million by 2050.
With no cure in sight, experts are increasingly focusing on prevention strategies that would involve identifying those most at risk.