After the age of 65, the risk of developing Alzheimer’s disease doubles every 5
years. Now, in line with this, new research finds that the brain’s ability to clear away
a toxic protein fragment associated with the disease is much reduced in older
people.
After the age of 65, the risk of developing Alzheimer’s disease doubles every 5
years.
In the Annals of Neurology, researchers from Washington University in St.
Louis, MO, describe how they found the brains of older people took much longer to clear
away amyloid beta 42, the main ingredient of the protein plaques that clog up the brain
in Alzheimer’s disease.
Randall J. Bateman, senior author and professor of neurology, says:
“We found that people in their 30s typically take about 4 hours to clear half
the amyloid beta 42 from the brain. In this new study, we show that at over 80 years
old, it takes more than 10 hours.”
If it is not cleared away, there is a higher chance that amyloid beta 42 – a protein
fragment that is a natural by-product of brain activity – will clump into plaques that
disrupt brain functions, such as communication between cells.
Scientists have long suspected that these plaques are one of the main drivers of
Alzheimer’s disease, a form of dementia.
Dementia is a progressive condition where memory, thinking and behavior deteriorate
until it is no longer possible to have a conversation and look after oneself. Although
the condition mainly affects older people, it is not a normal part of aging.
According to the World Health Organization, there are around 48 million people
worldwide with dementia, and this figure is rising by nearly 8 million each year.
Alzheimer’s disease contributes to around two-thirds of these cases.
Lower rates of amyloid beta 42 clearance in people with symptoms of Alzheimer’s
For their study, Prof. Bateman and colleagues tested 100 volunteers aged from 60 to
87. Half of these participants were showing clinical signs of Alzheimer’s disease, such as memory
problems, and 62 had plaques forming in their brains.
The researchers established these signs and symptoms from the detailed mental and
physical evaluations that the participants underwent. As well as brain scans to check
for plaques, they tested the participants’ cerebrospinal fluid using technology they
had developed themselves.
Through using this technology – called SILK (short for stable isotope-linked kinetics) – the
researchers can observe what happens to amyloid beta 42 and other proteins.
In participants who were showing evidence of plaques, the team saw that
amyloid beta 42 was more likely to drop out of the fluid that bathes the brain and
accumulate into plaques.
Also, lower rates of amyloid beta 42 clearance – such as those the researchers saw in
the older participants – were linked to symptoms of Alzheimer’s disease, including
memory impairment, personality changes and dementia.
Prof. Bateman says scientists believe the brain has four ways of disposing of amyloid
beta: moving it into the spine, forcing it through the blood-brain barrier, dissolving
it or absorbing it with other proteins, or depositing it as plaques. He concludes:
“Through additional studies like this, we’re hoping to identify which of
the first three channels for amyloid beta disposal are slowing down as the brain ages.
That may help us in our efforts to develop new treatments.”
Medical News Today also recently learned about a study that suggests one’s
sleep position may affect risk of developing
Alzheimer’s disease. Should the findings be replicated in humans, it would appear the
brain clears away amyloid beta and other waste products more effectively when we sleep on
our side as opposed to on the stomach or on the back.
Written by Catharine Paddock PhD
Copyright: Medical News Today
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