A recent scientific breakthrough in the study of Alzheimer's has linked a new protein to the disease, which may help scientists catch early discovery in people who are developing the disease but have yet to show symptoms. The results of this study were unveiled at the Alzheimer's Association International Conference.

Scientists already know two proteins, amyloid and tau, that are linked to development of the brain plaques that build up on brains deep into Alzheimer's disease. Presence of amyloid and tau were thought to be the biggest hallmarks of Alzheimer's, and have been used in diagnosing the disease post-mortem. Scientists had been looking for ways to see the protein on living brains -- such as doing MRIs. But this new protein may be even better.

Many people have plaque in their brain, but no sign of the mental impairment associated with Alzheimer's. This new protein may be an even bigger indicator of the disease. Studies showed that autopsies done on 342 people showed that brains with the new protein present were 10 times more likely to show signs of mental impairment before they died than in brains without the protein.

This new discovery could give scientists and researchers a new focus for developing Alzheimer's treatment.

Dr. Keith Josephs of the Mayo Clinic the research study on the new brain protein, called TDP-43. Its presence has already been linked to amyotrophic lateral sclerosis, or Lou Gehrig's disease, and frontotemporal dementia.

Researchers studied 342 elderly patients at the Mayo clinic. They found amyloid plaques in all participants but not all participants showed signs of Alzheimer's. 57% of the patients, however, had the new protein. Of these, 98% showed signs of dementia, compared to 81% without the protein.

Researchers estimated that less than 5% of people in the general population would have the abnormal protein now thought to be associated with Alzheimer's.

This new work could be major. "If there are 2 million people walking around this country with Alzheimer's but they're not showing any symptoms of it, think of how major that is," Josephs said. "If you have this protein, you're guaranteed to have symptoms. If you do not, you have a 20 percent chance you won't show symptoms even though you have" amyloid build up in the brain.

In another new development revealed at the Alzheimer's Association International Conference, researchers revealed a new type of imaging that can show tau build up in living people. Previously, tau had only been seen in autopsies done after death. This new imaging could be crucial to diagnosing and catching Alzheimer's early. Eli Lilly & Co. developed this new technology.

The other protein believed to be associated with Alzheimer's, amyloid, can already be seen on living patients through imaging.

"This is very important," said Laurie Ryan of the National Institute on Aging. She said that it could help diagnose Alzheimer's and enroll people in studies testing treatments.

Research from Massachusetts General Hospital shows that scans on 56 older people believed to be cognitively normal showed that tau buildup in several brain regions correlated with memory decline. Tau build up is thought to be more closely related to Alzheimer's than amyloid build up.