Night shifts could raise your risk of Alzheimer's: Disruptions to the body clock may trigger memory loss
- Jet lag-style sleep problems suffered by shift workers may cause dementia
- Alterations to the body clock can trigger memory and learning loss
- Tests on mice found cutting their dark hours made them more lethargic
- They also had reduced levels of a key brain antioxidant called glutathione
Jet lag-style sleep problems, suffered by shift workers and frequent fliers, may cause Alzheimer’s disease, according to new research.
Scientists have produced the first evidence that alterations to the body clock really can trigger the memory and learning loss symptoms that are a hallmark of dementia.
Experiments on mice found shortening their dark hours at night made them more lethargic and less able to work out a water maze.
They also had reduced levels of a key brain antioxidant called glutathione, an emerging factor in research into the causes of Alzheimer’s.
The researchers said their findings may lead to more emphasis on managing the sleep habits of people at risk for dementia and those with mild cognitive impairment, which can be an early warning sign of the mental illness.
Working night shifts has been linked to damging the immune system, raising the risk of a host of diseases including Alzheimer’s.
Previous research has revealed chronic sleep loss can lead to irreversible loss of brain cells. Another study found poor sleep allows a rogue protein called beta-amyloid to build up in the brain, destroying memory and leading to Alzheimer’s.
Professor Gregory Brewer, of the University of California, Irvine, said: “This study suggests clinicians and caregivers should add good sleep habits to regular exercise and a healthy diet to maximize good memory.”
The study published in the Journal of Alzheimer’s Disease said chemical changes in brain cells caused by disturbances in the body’s day-night cycle may be a key underlying cause of the learning and memory loss associated with dementia.
It has found for the first time that circadian rhythm, or the body clock, altering sleep disruptions similar to jet lag promote memory problems and chemical alterations in the brain.
People with Alzheimer’s often have insomnia or may experience changes in their sleep schedule, but scientists do not completely understand why these disturbances occur.
Prof Brewer said: “The issue is whether poor sleep accelerates the development of Alzheimer’s disease or vice versa. It is a chicken-or-egg dilemma, but our research points to disruption of sleep as the accelerator of memory loss.”
In order to examine the link, his researchers altered normal day-night patterns with an eight-hour shortening of the dark period every three days for young mice genetically engineered to develop a rodent version of Alzheimer’s, and normal mice.
The resulting jet lag greatly reduced activity in both groups and in water maze tests the Alzheimer’s mice had significant learning impairments absent in those with the same condition that were not exposed to light-dark variations, and in normal mice with jet lag.
In follow-up tissue studies, they saw that jet lag caused a decrease in glutathione levels in the brain cells of all the mice. But these levels were much lower in the Alzheimer’s mice and corresponded to poor performance in the water maze tests. Glutathione is a major antioxidant that helps prevent damage to essential cellular components.
The researchers explained that glutathione deficiencies produce changes in reactions between electrons in the brain, which may lead to oxidative stress which causes learning and memory loss, leading to Alzheimer’s. Prof Brewer said drugs that target these reactions could potentially provide a treatment.
Scientists have produced the first evidence that alterations to the body clock really can trigger the memory and learning loss symptoms that are a hallmark of dementia
Alzheimer’s and other forms of dementia affect more than 800,000 Britons and, worldwide, the number of sufferers is predicted to treble to 44 million by 2050 as the population ages. With existing drugs of limited use and search for a cure ending in disappointment time and time again, some doctors argue that changes to diet and lifestyle offer the best chance of staving off the disease.
If sleep is as important as believed, sleep therapies could help delay the onset of the disease, as well as slow its progression in those who already have it.
Dementia experts called for more research after a US study found jet lag-style sleep problems suffered by shift workers and frequent fliers may cause the disease.
Laura Phipps, of Alzheimer’s Research UK, said: “This study in mice suggests sleep disruptions can disturb the function of the brain in mice both with and without features of Alzheimer’s.
“We know sleep changes can be common in people with Alzheimer’s, but it is hard to know whether these disturbances contribute to, or result from, the disease.
“Sleep can influence everyone’s ability to function in the short-term and a good night’s sleep is important for people with dementia and their carers.
“While these early results suggest a mechanism through which sleep changes could contribute to memory problems in young mice, the long-term impacts of disrupted sleep on brain health or risk of Alzheimer’s in people still need to be explored in more detail.”
The researchers said their findings published in the Journal of Alzheimer’s Disease may lead to more emphasis on managing the sleep habits of people at risk for dementia and those with mild cognitive impairment, which can be an early warning sign of the mental illness.
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