An Alzheimer’s drug that clears away plaque build-up in the brain could slow progression of the disease and delay the onset of symptoms, early trials have shown. There is currently no cure for the disease, which can severely affect memory and impact people’s ability to carry out daily tasks, and the medicines available can only reduce symptoms. But a new drug called Trontinemab is showing promising results, the Alzheimer’s Association International Conference in Toronto was told. The drug has been tested on a small number of patients, but 49 out of 54 with early-stage Alzheimer's showed signs of improvement within 28 weeks during a trial, according to Roche, the pharmaceutical company behind the drug. Researchers said 91 per cent of the participants showed a reduction in clusters of protein on their brains, known as amyloid plaques – a key marker of Alzheimer's. Alzheimer's is thought to be caused by an abnormal build-up of this protein around brain cells, while another protein called tau forms tangles within brain cells. These can interrupt the chemical messengers responsible for sending signals between brain cells, according to the NHS. The new drug was found to reduce amyloid proteins to a level so low that scan results on patients taking it for seven months were considered to be “amyloid negative”. It is thought that the clearance of plaques slows down the progression of the disease and delays the onset of symptoms. “Alzheimer’s disease represents one of the greatest challenges in healthcare today, and tackling it requires early detection and effective therapeutics,” Dr Levi Garraway, chief medical officer of Roche, said. He added: “Trontinemab is designed to target a key driver of Alzheimer’s disease biology more effectively in the brain. Combining new treatment avenues with advanced diagnostics may enable earlier and potentially more effective intervention.” Professor Sir John Hardy, the chairman of molecular biology of neurological disease at University College London’s Institute of Neurology, who was not involved in the trial, told The Telegraph the drug was a “massive improvement” and works faster than other Alzheimer’s drugs on the market. “There is no doubt this could be game-changing. We hope that if we can use these drugs to people early, we can halt the progression of disease, even before people have symptoms. Now we need to see the size of the clinical effect,” he said. However, the drug does have some side effects, with five participants of 149 (3 per cent) suffering from lesions or swelling in their brains after taking it. But all the participants recovered, and it was considered to be safer than other Alzheimer's drugs that have resulted in 17 per cent of participants experiencing similar side effects. The final part of the trial, which will test the drug on a large number of patients, is yet to be carried out. But if it is successful, health bodies in the UK will need to decide whether it is cost-effective enough to use on the NHS. An estimated 982,000 people are living with some form of dementia, including Alzheimer's, in the UK, with the disease most common in people over the age of 65. But more than a third of people with the condition do not have a diagnosis. The number of those with the disease is expected to rise to 1.4 million by 2040, according to the Alzheimer’s Society.