A simple eye test might be able to detect Alzheimer's and other diseases before symptoms develop, according to UK scientists.
The technique uses fluorescent markers which attach to dying cells which can be seen in the retina and give an early indication of brain cell death.
The research has been carried out on mice, but human trials are planned.
Scientists from University College London hope this could lead to a high street opticians test for the disease.
The research, which is published in the journal, Cell Death and Disease, could enable scientists to overcome the difficulty of investigating what is happening inside the brains of those with Alzheimer's.
They currently have to rely on expensive MRI scans or post-mortems.
This new technique enables scientists to track the progress of brain disease by looking at dying cells in the retina.