‘Revolutionary’ blood test could predict who will develop Alzheimer’s disease

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A blood test to detect two molecules that act as indicators of a person’s likelihood of contracting Alzheimer’s disease later in life could be a game-changer, according to a new study.

Both molecules – P-tau181, a tau protein, and light neurofilament polypeptide (NfL) – are found in plasma, the light yellow fluid that makes up 55% of our blood.

In a sample of 557 people aged 60 to 70, the presence of elevated levels of P-tau181 and NfL were the most accurate predictors of patient progression from mild cognitive impairment (MCI) to severe problems with memory and reflection, typical of Alzheimer’s disease. .

Researchers say blood tests to detect levels of the two molecules could allow doctors to track the progression of Alzheimer’s disease in populations at risk.

New study could help development of routine blood tests to track Alzheimer’s disease progression in at-risk populations

“Our study is new in the way we approach the individualized predictive value of plasma biomarkers for Alzheimer’s disease,” say experts from Lund University in Sweden.

“The combination of plasma biomarkers can be of great value in identifying people with MCI who will progress to Alzheimer’s disease in clinical trials and in clinical practice.

Oxford University Professor Masud Husain, who was not involved in the study, called her a “potential game changer”.

“For the first time, we have a blood test that can well predict the risk of further development of Alzheimer’s disease in people who have mild cognitive symptoms,” he said.

“We need further validation, but in the context of other recent findings, this could be a transformative step towards earlier diagnosis, as well as testing new treatments at early stages of the disease.

Both molecules – P-tau181, a tau protein and light neurofilamentous polypeptide (NfL) – are found in plasma (pictured), the light yellow fluid that makes up 55% of our blood.

About 50 million people around the world are living with Alzheimer’s disease – which accounts for between 50% and 70% of dementia cases.

Although the exact cause of Alzheimer’s disease is not yet fully understood, it is thought to be caused by the abnormal buildup of proteins in and around brain cells.

WHAT IS TAU?

Tau is considered to be a protein characteristic of Alzheimer’s disease and other brain diseases.

It is mainly found in brain cells (neurons). But in people with Alzheimer’s disease, proteins are distorted.

And Alzheimer’s disease is well known for its tangles or clumps which are made up of tau proteins.

Scientists have long emphasized the importance of tau in Alzheimer’s disease because of the evidence linking the spread of tau to the progression of the disease.

Another important protein is beta-amyloid, the accumulation of which is largely completed at an early clinical stage known as mild neurocognitive disorder.

However, the accumulation of tau continues throughout the course of the disease, reports the Bright Focus Foundation.

Therefore, the total amount of abnormal tau in the brain is related to the stage and severity of the disease.

Tau clumps are not yet measurable with an available blood test, although research is ongoing.

In the case of amyloid, a PET will not identify the severity of the disease due to the early buildup of amyloid.

Fluid from the spinal canal is taken to analyze proteins related to dementia (known as a lumbar puncture). But this is not routinely used as a dementia test and is more commonly used for research purposes.

One of the proteins involved is called amyloid, the deposits of which form plaques around brain cells.

The other protein is called tau, the deposits of which form tangles in brain cells.

While it’s unclear exactly what causes this process, scientists now know that it begins several years before symptoms appear.

Led by Oskar Hansson of Lund University, the researchers developed and validated models that could predict an individual’s risk for cognitive decline and subsequent transition to Alzheimer’s disease.

They used data from 573 patients with minor cognitive impairment from two independent cohorts.

The researchers compared the accuracy of several models based on various combinations of blood biomarkers to predict cognitive decline and dementia over four years.

A decline in brain function was determined by the Mini – Mental State Examination (MMSE) – a 30-point test that consists of a series of questions and tests a number of different mental abilities, including memory, attention. and the language of a person.

They found that the main predictors were P-tau181, a type of tau protein already known to be a hallmark of Alzheimer’s disease, and NfL known to be a marker for neuroaxonal damage.

Together, they were almost 90% accurate in identifying those who developed the disease.

The results demonstrate the value of using specific combinations of blood biomarkers to make predictions for specific individuals with MCI.

“Like dementia, MCI is an umbrella term describing several symptoms and can be caused by a number of different underlying diseases,” said Dr Sara Imarisio of Alzheimer’s Research UK.

“We know that over 50% of people with MCI will develop dementia, and it is important that we try to identify who will and who will not progress so that we can offer appropriate treatment and counseling.

However, other scientists who were not involved in the study believe more research with larger cohorts is needed.

“ This study only looked at a few hundred people, but if these blood biomarkers can predict Alzheimer’s disease in larger and more diverse groups, we could see a revolution in the way we test new drugs. against dementia, ” said Dr Richard Oakley, head of research at Alzheimer’s. Society.

“ Blood tests to predict dementia are advancing at breakneck speed, but if the government does not double funding for dementia research as it promised, people with dementia will not benefit from these new breakthroughs. ”

Professor Tara Spiers-Jones, an expert in neurodegeneration at the University of Edinburgh, pointed out that some of the people who were predicted to have a high likelihood of disease because of these proteins in their blood did not develop Alzheimer’s disease.

Likewise, some people with a low predicted probability went on to develop the disease.

The study is an important step on the road to developing a blood test for Alzheimer’s disease, but it is important to note that we are not there yet, ”said Professor Spiers-Jones.

“As the authors correctly note, more studies on larger populations and standardized methods to run and interpret these tests are needed to confirm their usefulness.”

The study was published in Nature Aging.

SENIORS IN POLLUTED AREAS ‘MORE LIKELY TO DEVELOP ALZHEIMER’S’

Older people living in polluted areas are at higher risk of developing Alzheimer’s disease, warns a new study from JAMA Neurology.

Researchers looked at PET (positron emission tomography) scans of more than 18,000 elderly people in the United States who suffered from dementia or mild cognitive impairment.

They then mapped out their zip codes and determined the air pollution levels in each neighborhood based on data from the Environmental Protection Agency, which measures ground-level ozone and air pollution particles in a diameter less than 2.5 microns, called PM2.5.

PET scans of older people living in the most polluted areas were 10% more likely to show amyloid plaques – hard proteins that clump between nerve cells, the researchers found.

Although not all types of dementia are associated with these plaques, they are a hallmark of Alzheimer’s disease.

The first author, Dr Leonardo Iaccarino, said: “Exposure in our daily life to PM2.5, even at levels that would be considered normal, could help induce a chronic inflammatory response.

“Over time, this could impact brain health in a number of ways, including contributing to a buildup of amyloid plaques.

The more pollutants in the air, the more likely people are to have a scan with amyloid plaques, the researchers found.

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