Scientists have found a surprising new way to tackle Alzheimer’s disease – by targeting the liver rather than the brain.Their research suggests boosting the liver’s ability to clear a toxic sticky protein, called amyloid, from the blood can reduce its build-up in the brain and even reverse memory loss. The research in mice, published recently in the journal Neuron, suggests the liver plays a far greater role in Alzheimer’s than previously understood – and targeting it could be a new way to protect against the incurable disease, which affects around one million people in the UK.Alzheimer’s is thought to be caused by a build-up of amyloid, which clumps into plaques between brain cells and blocks the signals they use to communicate. A second protein, tau, causes damage by twisting into tangles that strangle cells from within.Current drugs can slow the decline but cannot stop or reverse it, and many carry troubling side-effects such as nausea, dizziness and, in some cases, brain swelling or bleeding.Until now, scientists have focused almost entirely on what happens inside the brain – and on a gene called APOE, which produces a protein to help the brain’s own immune cells identify and clear away harmful amyloid.Amyloid is a waste product left behind when brain cells break down proteins as part of their everyday work – much like exhaust from a car engine. The brain produces it constantly and normally clears it away efficiently.But up to 60 per cent of the amyloid produced in the brain spills over into the bloodstream, where the liver is responsible for breaking it down and flushing it out. To do this, it too uses the APOE gene to help clear it away.However, around one in four people in the UK carry a rogue version of the gene, known as APOE4, which is far less efficient at clearing amyloid, leaving them at higher risk of the disease.Everyone experiences dementia differently. Use this checklist to help you make a note of your symptoms before you talk to your GP. Dr Richard Oakley, of Alzheimer’s Society, said the findings raise the idea of ‘looking outside of the brain for ways of reducing amyloid in the early stages of Alzheimer’s disease’Carrying one copy of APOE4 raises the risk of developing Alzheimer’s two- to three-fold.Around 2 to 3 per cent of the population carry two copies, raising their risk up to 15-fold.It means amyloid that should be removed lingers, gradually building up in the brain and hardening into plaques that damage and destroy brain cells.But scientists now hope to develop a treatment – using a one-off gene therapy injection – that deploys the power of the liver to cleanse the blood of harmful amyloid before it gets a chance to settle in the brain. It would be targeted at those carrying at least one copy of the APOE4 gene, putting them at higher risk.The secret to the new therapy lies in an extraordinarily rare version of the APOE gene, known as APOE3 Christchurch and carried by only around one in every 25,000 people.It has a single, subtle difference in its genetic code that appears to make it far better than ordinary versions of the gene at helping the body clear away amyloid.APOE3 Christchurch first came to scientists’ attention in 2019 when they investigated the case of a woman in Colombia who carried a rare genetic mutation which typically causes Alzheimer’s in everyone who has it by the age of 50.But the woman had defied all the odds, remaining mentally sharp well into old age.Genetic sequencing revealed it was due to the fact that she had two copies of APOE3 Christchurch.In the latest study, scientists at Chongqing Medical University and the Army Medical University in China packaged the APOE3 Christchurch gene inside an adeno-associated virus – a type routinely used in gene therapy that has been stripped of its ability to cause disease and acts purely as a delivery vehicle.They injected it into the bloodstream of mice engineered to carry the APOE4 gene and develop Alzheimer’s-like changes in the brain.The results showed the treatment almost halved the level of amyloid plaques in the brain as liver cells became significantly better at absorbing amyloid from the blood.Scientists said they can’t be sure exactly why the APOE3 Christchurch gene is so much better at clearing the deposits.But Dr Zhong-Yuan Yu, one of the study’s lead authors, told Good Health: ‘By enhancing amyloid clearance in the liver cells, the Christchurch variant strengthens the body’s ability to remove amyloid from the blood and shifts the balance toward removal from the brain.‘The effects were also not limited to reducing amyloid plaques. We saw less inflammation, less nerve cell damage and improved memory in the mice.’Dr Richard Oakley, associate director of research and innovation at Alzheimer’s Society, said the findings raise ‘the interesting idea of looking outside of the brain for ways of reducing amyloid in the early stages of Alzheimer’s disease’.But he stressed the new research remains at a very early stage and has been tested only in mice.‘We will also need to see how tau tangles impact this approach, which aren’t present in the mouse model used. We know, along with amyloid plaques, these are an important part of Alzheimer’s disease.’The researchers said the next step is to test the therapy in larger animals – most likely primates – before moving on to humans.Gene therapies take at least five years to progress from animal studies to a first human trial, so it could be a decade or more before any treatment is approved.WHAT IS DEMENTIA? Dementia is an umbrella term used to describe a range of progressive neurological disorders, that is, conditions affecting the brain.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 1million 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 2040 will rise to more than 1.4million. 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