Sleep’s ‘garbage truck’ function in the brain could be key to dementia risk

Sleep works to clean out metabolic waste from the brain, so suffering from a poor night’s rest in middle age may be the first sign of Alzheimer’s disease and could contribute to its onset, Melbourne researchers have found.

Poor sleep in middle age may be the first sign of Alzheimer’s disease and contribute to its onset, Melbourne researchers have found.

Florey Institute of Neuroscience and Mental Health researchers have discovered that certain stages of sleep — particularly the dream stage — act as a “garbage truck” for the brain, cleaning out the build-up of metabolic waste that collects over the day.

Middle-aged adults are now needed for a $1.1 million study that will compare long-term sleep habits to brain scans and memory tests, looking for the earliest signs of disease.

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A parliamentary inquiry into Sleep Health Awareness in Australia is due to begin next week.

Abnormal proteins start to accumulate in the brain decades before dementia symptoms appear. While studies have shown sleep deprivation in the short-term increases the build-up of this amyloid protein, the long-term consequence of poor sleep on the brain is not fully known.

Lead researcher Dr Matthew Pase said by deciphering how sleep was linked to cognitive decline, they hoped sleep quality could be used to remedy the chemical changes needed to keep brains healthy.

“Amyloid proteins build up in the brain normally as a function of being awake,” he said.

“We now have evidence to suggest that one function of sleep seems to be the flushing of metabolic waste that accumulates during the day.

“We’ll look at whether poor sleep is associated with the worsening of amyloid and cognitive decline over time.”

Dr Pase’s previous research, which followed more than 300 middle-aged adults for 12 years, found those who spent less time in the dream stage — a deep slumber called REM — were at higher risk of developing dementia in the subsequent 15 years.

The study kicks off as hearings for a parliamentary inquiry into Sleep Health Awareness in Australia begin next week.

Dr Pase and Dr Yen Ying Lim will recruit 280 adults through the Healthy Brain Project, analysing their sleep at home for two weeks and overnight in the laboratory.

The National Health and Medical Research Council funded study will scan participants’ brains to map volume and structure, and will involve detailed testing of memory and thinking skills. Tests will be repeated every two years to detect subtle changes.

“Sleep disorders are prevalent, but different aspects of sleep are modifiable,” he said.

“It’s a possibility that by understanding what aspects of sleep relate to different aspects of dementia, there might be more focus on ensuring people get good sleep.”

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