Science

Brain cells’ slow ability to clean themselves may be what causes Alzheimer’s, study finds 

The origin of Alzheimer’s disease has baffled scientists for more than a century, but new research claims to have found the culprit – it could be caused by cells’ slowing ability to clean themselves.

Researchers from the University of California, Riverside (UCR) suggests the slowing is seen in people over the age of 65 – the prime age for diagnosis- and is what likely causes the unhealthy brain buildup.

The slowing, known as autophagy, can be induced by fasting, as cells do not get enough protein from an individual’s diet – and they fill the void by recycling proteins already present in cells. 

UCR Chemistry Professor Ryan Julian, who led the study, says drugs are already being tested to improve autophagy and if this is the cause of Alzheimer’s we could see a potential preventive drug in the near future. 

‘If a slowdown in autophagy is the underlying cause, things that increase it should have the beneficial, opposite effect,’ Julian said. 

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The origin of Alzheimer's disease has baffled scientists for more than a century, but new research claims to have found the culprit ¿ it could be caused by cells' slowing ability to clean themselves

The origin of Alzheimer’s disease has baffled scientists for more than a century, but new research claims to have found the culprit – it could be caused by cells’ slowing ability to clean themselves

Around 6.2 million Americans are living with Alzheimer’s disease as of this year, with more than one in nine age 65 or older.

The disease was discovered by Dr Alios Alzheimer in 1906, who noticed changes in the brain tissue of a woman who had died of an unusual mental illness – and how it comes about has since remained a mystery.

Doctors typically diagnose Alzheimer’s when they find a combination of amyloid plaques and neurofibrillary tangles, coupled with dimension.

However, Julian said in a statement: ‘Roughly 20% of people have the plaques, but no signs of dementia.

‘This makes it seem as though the plaques themselves are not the cause.’

The slowing, known as autophagy, can be induced by fasting, as cells do not get enough protein from an individual's diet - and they fill the void by recycling proteins already present in cells

The slowing, known as autophagy, can be induced by fasting, as cells do not get enough protein from an individual’s diet – and they fill the void by recycling proteins already present in cells

Now, Julian and his colleagues believe they have cracked to code of the disease by looking at proteins inside the brain.

The abnormal build-up is known to cause Alzheimer’s, which involves two types of proteins.

One is called amyloid, deposits of which form plaques around brain cells, and the other is called tau, deposits of which form tangles within brain cells.

The team began the study by focusing on tau proteins, which are found to be misfolded and abnormally shaped in brains of people with Alzheimer’s.

Tau proteins help stabilize the internal skeleton of nerve cells, also known as neurons, in the brain.

Although difficult to detect, the different form of tau allowed the scientists to distinguish between people who expressed no outward signs of dementia from those who did.

Julian’s lab at the university focuses on the different forms that a single molecule can take, called isomers, which also helped lead them to the culprit.

‘An isomer is the same molecule with a different three-dimensional orientation than the original,’ Julian said. 

‘A common example would be hands. Hands are isomers of each other, mirror images but not exact copies. Isomers can actually have a handedness.’

The amino acids that make up proteins can either be right-handed or left-handed isomers. 

The key difference between left- and right-handed amino acids is that the amine groups of left-handed amino acid occur in the left-hand side of the molecule whereas the amine group of right handed amino acids is in the right-hand side. 

Normally, Julian said, proteins in living things are made from all left-handed amino acids.

With all of this in mind, the team scanned all the proteins in donated brain samples. 

The found those with brain buildup but no dementia had normal tau while a different-handed form of tau was found in those who developed plaques or tangles as well as dementia.

Most proteins in the body have a half-life of less than 48 hours, but if they are found to linger, certain amino acids can convert into the other-handed isomer.

‘If you try to put a right-handed glove on your left hand, it doesn’t work too well. It’s a similar problem in biology; molecules don’t work the way they’re supposed to after a while because a left-handed glove can actually convert into a right-handed glove that doesn’t fit,’ Julian said. 

WHAT IS DEMENTIA? THE KILLER DISEASE THAT ROBS SUFFERERS OF THEIR MEMORIES

Dementia is an umbrella term used to describe a range of neurological disorders

Dementia is an umbrella term used to describe a range of neurological disorders

A GLOBAL CONCERN 

Dementia is an umbrella term used to describe a range of progressive neurological disorders (those affecting the brain) which impact memory, thinking and behaviour. 

There are many different types of dementia, of which Alzheimer’s disease is the most common.

Some people may have a combination of types of dementia.

Regardless of which type is diagnosed, each person will experience their dementia in their own unique way.

Dementia is a global concern but it is most often seen in wealthier countries, where people are likely to live into very old age.

HOW MANY PEOPLE ARE AFFECTED?

The Alzheimer’s Society reports there are more than 850,000 people living with dementia in the UK today, of which more than 500,000 have Alzheimer’s.

It is estimated that the number of people living with dementia in the UK by 2025 will rise to over 1 million.

In the US, it’s estimated there are 5.5 million Alzheimer’s sufferers. A similar percentage rise is expected in the coming years.

As a person’s age increases, so does the risk of them developing dementia.

Rates of diagnosis are improving but many people with dementia are thought to still be undiagnosed.

IS THERE A CURE?

Currently there is no cure for dementia.

But new drugs can slow down its progression and the earlier it is spotted the more effective treatments are.

Source: Alzheimer’s Society 


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