Washington, Dec 30 (PTI) Chronic poor sleep maycontribute to cognitive decline, according to a study thatshows wakeful brain produces more of the Alzheimer's proteinamyloid beta than its waste-disposal system can handle.
Levels of the protein rise, potentially setting off asequence of changes to the brain that can end with dementia,researchers said.
"This study is the clearest demonstration in humans thatsleep disruption leads to an increased risk of Alzheimer'sdisease through an amyloid beta mechanism," said RandallBateman, from the Washington University School of Medicine, StLouis in the US.
"The study showed that it was due to overproduction ofamyloid beta during sleep deprivation," Bateman said.
For the research published in the journal Annals ofNeurology, the scientists studied eight people aged between 30to 60 years with no sleep or cognitive problems.
The participants were assigned randomly to one of threescenarios: having a normal night's sleep without any sleepaids; staying up all night; or sleeping after treatment withsodium oxybate, a prescription medication for sleep disorders.
Sodium oxybate increases slow-wave sleep-the deep,dreamless phase of sleep that people need to wake up feelingrefreshed.
Each scenario occurred during 36 hours of monitoring,starting in the morning and continuing through the afternoonof the following day.
The researchers took samples of the fluid that surroundsthe brain and spinal cord every two hours to monitor howamyloid beta levels change with time of day and tiredness.
All eight participants returned four to six months laterto undertake a second scenario, and four people completed allthree.
Studying the same people under different conditionsprovides the statistical power to detect changes in amyloidbeta levels.
Amyloid beta levels in sleep-deprived people were 25 to30 per cent higher than in those who had slept the nightthrough.
After a sleepless night, amyloid beta levels were on parwith the levels seen in people genetically predisposed todevelop Alzheimer's at a young age.
"This information could help us figure out how to reduceamyloid beta deposition over time in people whose sleep ischronically disrupted," said Brendan Lucey, from theWashington University School of Medicine. PTI SNESNE.
This is unedited, unformatted feed from the Press Trust of India wire.