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Study finds link between circadian disruption and Alzheimer’s

Following a research study at the Rensselaer Polytechnic Institute in New York, Dr Jennifer Hurley said, “Taking care of our sleep or circadian rhythms – sometimes called good sleep hygiene – may be able to reduce amyloid-beta burden over our lifespan,” she said. “Reducing amyloid burden could mean a reduction in Alzheimer’s symptoms or a delay in the onset or progression of the disease.”

Dr Hurley led the project to research the link between sleep disturbance, the resulting disruption to natural circadian cycles, and the development of Alzheimer’s disease.

The findings show that humans’ 24-hour circadian clock controls the brain’s ability to mop up wayward proteins linked to Alzheimer’s disease. If the scientists are right, the work would explain, at least in part, how disruption to circadian rhythms and sleep disturbances might feed into the onset and progression of Alzheimer’s disease and how preventing such disruption might stave off the condition.

“Circadian disruption is correlated with Alzheimer’s diagnosis, and it has been suggested that sleep disruptions could be an early warning sign of Alzheimer’s disease,” said Dr Hurley.

Alzheimer’s is progressive and linked to abnormal plaques and tangles of proteins that steadily build up in the brain. The disease is the most common cause of dementia and affects more than half a million people in the UK, a figure that is set to rise.

While sleep disturbances often arise before Alzheimer’s disease, Hurley and many other scientists suspect there is a complex interplay between the two. Disrupting sleep and circadian rhythms allowed amyloid beta to build up, Hurley said, but this, in turn, damaged brain cells that ran the circadian clock, causing further accumulation of amyloid-beta.

“We have known for a while that there is a rhythm in the clearance of amyloid-beta in the brain,” Hurley said. “As we age, and more so in Alzheimer’s patients, this rhythm disappears. This loss could lead to the increase of amyloid-beta in the brain.”

The findings point to therapies that could potentially reduce the risk of Alzheimer’s or lessen the severity of the symptoms. Hurley said it may be possible to stimulate the brain’s ability to clear out amyloid-beta with simple interventions, such as exposure to light, or via more sophisticated therapies that boost the activity of the immune cells.