Does sleep apnoea cause dementia?

New research has found that people with bedtime disorder sleep apnoea have higher amounts of a rogue brain protein that causes Alzheimer’s disease.

Sleep apnoea causes the airways to become obstructed. It is the most common sleep-related breathing disorder suffered in adults and is twice as common in men as in women.

An estimated 1.5 million people in the UK suffer from it – and many will never have been formally diagnosed.

Alzheimer’s and other forms of dementia affect 850,000 people in the UK alone, a figure set to rise to two million by 2050. There is currently no cure for the condition and health experts are increasingly focusing on prevention strategies identifying those most at risk.

The findings of this study suggest that being a loud snorer could cause the condition and adds to a growing body of evidence that a good night’s sleep can protect against dementia.

Study author, Dr Diego Carvalho, of the Mayo Clinic in the United States, said: “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.”

The study 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.

Afterwards, the participants had PET (Positron Emission Tomography) scans to look for accumulation of tau tangles in the entorhinal cortex (The area of the brain that helps with memory, navigation and perception of time).

The researchers identified 43 of the volunteers – 15 per cent of the group – whose bed partners witnessed apnoeas when they were sleeping. They had an average of 4.5 per cent more tau than those who did not have apnoeas.

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.”

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