Scientists have developed a non-invasive and pain-free means of diagnosing brain diseases, including Alzheimer's.
Using magnetoencephalography (MEG) to record magnetic fields in the brain, the researchers could see brain cells communicating with each other while participants stared at a point of light.
Lead researcher Apostolos P Georgopoulos said: "This elegantly simple test allows us to glimpse into the brain as it is working.
"We were able to classify, with 100 percent accuracy, the various disease groups represented in the group of research subjects.
"This discovery gives scientists and physicians another tool to assess people's disease progression.
"In the future it could be applied when studying the effect of new treatments or drug therapies."
The team plans to collect more data on the six disease groups and begin to analyse research subjects with other brain diseases, including depression, post-traumatic stress disorder, autism and Parkinson's disease, to see if the same technique can be used.