Fragmented sleep 'may predict Alzheimer's'
30th January 2018 – Interrupted sleep may be an early warning of Alzheimer's disease, a study suggests.
People with Alzheimer's are known to experience disturbed sleep and disrupted sleep patterns when the body's internal body clock malfunctions.
Now, doctors at Washington School of Medicine in the US have found that fragmented sleep may occur in people long before they have any clinical signs of the disease. They say these findings might help doctors identify people at risk of Alzheimer's earlier than is currently possible.
The study, published in the journal JAMA Neurology, examined the circadian rhythms, controlled by the body's internal clock, in 189 people who showed no signs of Alzheimer's. The average age of the participants was 66.
Some had brain scans to look for amyloid plaques – a sticky build-up that accumulates between neurons and is a hallmark of Alzheimer's. Others had their spinal fluid tested for Alzheimer's-related proteins. Some had both scans and spinal fluid testing.
The amount of time they spent being active or at rest was measured using wrist activity monitors. They also completed detailed sleep diaries.
Of the participants, 139 tested negative for amyloid protein that is present before Alzheimer's develops. Most of these people had normal sleeping patterns, although some had circadian disruptions, probably caused by being elderly, having sleep apnoea, or for other reasons.
However, the remaining 50 individuals – who either had abnormal brain scans or abnormal spinal fluid – all experienced significant disruptions in their internal body clocks as a result of how much sleep they got at night and how active they were during the day.
The researchers say participants who experienced short spurts of activity and sleep over a 24 hour period were more likely to have amyloid plaque build-up in their brains.
A 'chicken and egg situation'
Dr David Reynolds, chief scientific officer at Alzheimer's Research UK, comments by email: "Research has faced a bit of a chicken and egg situation when looking at the links between sleep and dementia. While we know that people with Alzheimer's experience disturbed sleep patterns, whether this contributes to the disease or is an early consequence has been unclear.
"This study observes changes in daily rest and activity patterns at an early stage, where people are showing signs of Alzheimer's in the brain but before symptoms begin.
"In the past, studies have used sleep diaries to look at the links between sleep and health conditions, but the development of wearable activity monitors is helping researchers gain deeper and more accurate insight into the factors at play.
"We can't conclude from this study that napping more during the day can lead to dementia, and future studies will need to follow volunteers over longer periods of time. Studies like this add new pieces to the jigsaw of our understanding, and could lay the groundwork for new ways to detect the condition earlier, focusing on a range of factors and not just memory and thinking tests."