A simple eye test makes it possible to identify Alzheimer's disease 20 years before symptoms develop, according to new research.
Researchers found that patients with the devastating form of dementia had more than twice as much of a telltale brain protein in their retinas.
According to scientists, the protein begins to gather decades before symptoms develop which offers a window for early treatment when drugs and lifestyle changes are likelier to work.
The development opens the door to an inexpensive screening programme that would flag up those most at risk who would then undergo more extensive scanning.
The main chemical in turmeric is used to to light up amyloid deposits at the back of the eye, in the technique.
A link between the amount of the rogue protein in the eye and amyloid in the brain has long been suspected to indicate the presence of the condition. The retina is formed from the same tissue as the brain during the development of a baby in the womb.
Neurosurgeon professor Maya Koronyo-Hamaoui, of Cedars-Sinai Medical Center, Los Angeles, said: ''Analysis of retinal amyloid index (RAI) scores showed a 2.1-fold increase in Alzheimer's disease patients.''
The Cedars-Sinai research team collaborated with investigators at NeuroVision Imaging, Commonwealth Scientific and Industrial Research Organisation, University of Southern California, and UCLA for the study.
The researchers conducted a clinical trial on 16 AD patients who drank a solution that included curcumin.
The amyloid plaque lights up in the retina due to curcumin and is thus picked up in the scan.
The researchers then compared the patients with a group of younger, cognitively healthy individuals.
They found that their results were as accurate as those found via standard invasive methods.