Lack of Sleep may Increase the Risk of Alzheimer’s Disease
Insomnia increases the risk of Alzheimer’s disease – Research Finding
Young and middle-aged adults who suffer from insomnia and other sleep disorders may be more likely to develop Alzheimer’s in later life, research in mice suggests.
Insomnia may raise levels of amyloid beta in the brain. The protein is associated with Alzheimer’s disease. Photograph: Getty
Researchers monitored levels of amyloid beta, a protein fragment known to be linked to Alzheimer’s, in the brains of sleep-deprived mice with symptoms of the disease.
They found that preventing the mice from sleeping caused a 25% increase in amyloid beta levels. The peptide builds up in the brains of Alzheimer’s sufferers to form damaging plaques.
Amyloid beta levels were generally higher when mice were active than when they were sleeping, and animals that stayed awake longer had higher amounts of the peptide in their brains. The research will be published tomorrow in the journal Science.
Another study, also published in Science, links the finding to humans, showing that amyloid beta levels in the spinal fluid of volunteers increased when they were awake and fell during sleep.
Professor David Holtzman from the Barnes-Jewish Hospital in St Louis, US, where both studies were carried out, said: “The results suggest that we may need to prioritise treating sleep disorders not only for their many acute effects, but also for potential long-term impacts on brain health.”
The scientists also found a link with orexin, a protein involved in regulating the sleep cycle. When orexin was injected into the brains of mice, the animals stayed awake longer and levels of amyloid beta in their brains increased.
A drug that blocked the action of orexin led to a significant reduction in levels and increased the amount of sleep.
Three weeks of chronic sleep deprivation was enough to accelerate the deposition of amyloid plaque in the brains of the mice. But after two months of treatment with the orexin blocker, the deposits had shrunk by more than 80% in some cases.
“This suggests the possibility that a treatment like this could be tested to see if it could delay the onset of Alzheimer’s disease,” said Prof Holtzman.
He pointed out that as people age and their risk of Alzheimer’s increases, they usually sleep for shorter periods.
Further studies are being considered to see whether chronic sleep loss in young and middle-aged adults increases the risk of Alzheimer’s in later life.
Alzheimer’s is the most common form of dementia, affecting an estimated 700,000 people in the UK. The figure is expected to double within a generation.
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