Vaccines could be used to stamp out Alzheimer's in the future, according to new research.
Researchers at Harvard Medical School have found that the brain's own defence mechanism may actually be one of the causes of the neurodegenerative disease.
The build-up of a plaque caused by a sticky protein called beta amyloid has previously been linked to the onset of Alzheimer's but until now, scientists weren't sure of the plaque’s function.
The new research suggests it is an anti-microbial compound that forms part of the immune system and which is used as a defence against invading pathogens.
The findings are the result of the researchers injecting bacteria into the brains of mice that had been bred to develop plaque in the same way as humans.
The results suggest the plaques may grow to protect the brain against infections, but if they remain too long they can lead to inflammation and a series of steps that result in the onset of Alzheimer's.
The development of vaccines against such infections could effectively stop the brain disease from developing.
However, it may take years to find out which pathogens are involved and to develop medicine to fight them.
Alzheimer's is thought to be the cause of up to 70 per cent of dementia cases, of which the UK has around 850,000, according to the Alzheimer's Society.
Short-term memory loss is the most common early symptom of Alzheimer's, but the cause of the disease has proved difficult to ascertain.