Signs of Alzheimer’s could appear 25 years before the onset of the disease, according to new research, which has successfully mapped a ‘timeline’ of unseen progress before symptoms appear.

University of Washington researchers have successfully developed a timeline of unseen progress of Alzheimer’s before symptoms appear, suggesting that symptoms of the disease could be spotted 25 years before the onset of the disease.

The researchers studied families with a genetic risk of the disease, and have recently published their findings in the New England Journal of Medicine. Participants underwent blood and spinal fluid tests as well as brain scans and mental ability assessments, with the researchers finding that the earliest change- a drop in spinal fluid levels of the key ingredient of Alzheimer’s brain plaques – can be detected 25 years before the anticipated age of disease onset.

There are also key indicators that can be seen at 15 and 10 years into the development of the disease. At 15 years, raised levels of tau can be spotted in the spinal fluid, and shrinkage can also be detected in parts of the brain. Five years later, changes to the brain’s use of sugar glucose can also be identified, as well as slight memory problems.

Prof Clive Ballard, director of research at the Alzheimer’s Society, told the BBC: “This important research highlights that key changes in the brain, linked to the inherited form of Alzheimer’s disease, happen decades before symptoms show, which may have major implications for diagnosis and treatment in the future.

“These findings are a good indicator that there may be key changes in the brain happening early in people who develop non-hereditary Alzheimer’s disease, but we can’t be sure. Further research into this complex condition is needed to confirm a definite link.”

And Dr Eric Karran, director of Research at Alzheimer’s Research UK, said: “These results from people with the inherited form of Alzheimer’s seem to be very similar to the changes in the non-genetic, common form of the disease.

“It’s likely that any new treatment for Alzheimer’s would need to be given early to have the best chance of success.”