A bad sleep may be an early sign of Alzheimer’s if a study in mice also applies to people, say researchers.
Clumps of protein, called plaques, in the brain are thought to be a key component of the illness.
A study, published in the journal Science Translational Medicine, showed that when plaques first developed, the mice started having disrupted sleep.
The hunt for early hints that someone is developing Alzheimer’s is thought to be crucial for treating the disease.
A bad sleep may be an early sign of Alzheimer's if a study in mice also applies to people
People do not show problems with their memory or clarity of thought until very late on in the disease. At this point, parts of the brain will have been destroyed, meaning treatment will be very difficult or maybe even impossible.
It is why researchers want to start early, years before the first symptoms.
One large area of research is in plaques of beta amyloid which form on the brain.
Levels of the beta amyloid protein naturally rise and fall over 24 hours in both mice and people. However, the protein forms permanent plaques in Alzheimer’s disease.
Experiments at Washington University showed that nocturnal mice slept for 40 minutes during every hour of daylight. However, as soon brain plaques started to form the mice were sleeping for only 30 minutes.
One of the researchers, Prof. David Holtzman, said: “If sleep abnormalities begin this early in the course of human Alzheimer’s disease, those changes could provide us with an easily detectable sign of [the disease].”
“If these sleep problems exist, we don’t yet know exactly what form they take, reduced sleep overall or trouble staying asleep or something else entirely.”
However, findings in mice do not always apply to people are there are many reasons for disrupted sleep.
A team at Washington University School of Medicine has assembled a “timeline” of the unseen progress of Alzheimer’s before symptoms appear.
Scientists looked at families with a genetic risk of the disease.
Writing in the New England Journal of Medicine, they say signs appeared up to 25 years before the expected onset of the disease.
The 128 people in the study, from the UK, US and Australia, had a 50% chance of inheriting one of three mutations that are certain to cause early Alzheimer’s, which often develops in people’s 30s and 40s – much earlier than the more common form of Alzheimer’s which generally affects people in their 60s.
A team at Washington University School of Medicine has assembled a "timeline" of the unseen progress of Alzheimer's before symptoms appear
Those who carry the mutations will go on to develop the disease.
The researchers looked at the age the participants’ parents were when they developed the disease – and therefore how many years it was likely to be before they too showed symptoms.
They underwent blood and spinal fluid tests as well as brain scans and mental ability assessments.
The earliest change – a drop in spinal fluid levels of the key ingredient of Alzheimer’s brain plaques – can be detected 25 years before the anticipated age of disease onset, they suggest.
At 15 years, raised levels of tau, a structural protein in brain cells can be seen in spinal fluid – and shrinkage can also be detected within parts of the brain.
Changes in the brain’s use of the sugar glucose and slight memory problems become apparent 10 years before symptoms would appear, they suggest.
Researchers also tested other members of the families without the inherited mutations – and found no changes in the markers they tested for.