Discovery of new protein may help in early diagnosis of Alzheimer

A recent research at Rush University Medical Center recognized pathologic protein in the brain which may play a larger role in the development of clinical Alzheimer's disease.

Author of the study, Bryan James, said the finding could help researchers to understand the cause of memory loss and lead to new ways to approach studying Alzheimer's disease.

"Our study found that when the main characteristic pathologies of Alzheimer's disease, plaques and tangles, were mixed with a pathologic protein called TDP-43 in the brain, the combination was more likely to result in diagnosed Alzheimer's dementia than plaques and tangles alone," he said.

The abnormal protein, TDP-43 (short for 'hyperphosphorylated transactive response DNA-binding protein 43'), previously has been associated with frontal temporal dementia and amyotrophic lateral sclerosis (ALS, sometimes called Lou Gehrig's disease).

In recent years, TDP-43 also has been found in the brains of persons with other diseases, but most recently in Alzheimer's disease.

The hallmark pathologies of Alzheimer's disease are the accumulation of the protein beta-amyloid (called plaques) and an abnormal form of the protein tau (called tangles).

However, research has shown that the majority of persons with clinical Alzheimer's dementia also develop other disease pathologies in their brains as well, such as small strokes or protein deposits called Lewy bodies.

This combination, called 'mixed pathologies,' increases the risk for developing diagnosed Alzheimer's dementia above and beyond just having plaques and tangles in the brain.

"The clinical disease that we call 'Alzheimer's disease' is looking more and more like the result of the accumulation of a number of disease processes in the brain of older persons," James added.

The majority of persons with diagnosed Alzheimer's dementia actually have mixed pathologies in their brains, not just the plaques and tangles that are the known hallmarks of Alzheimer's disease.

"In particular, mixed Alzheimer's and TDP-43 pathologies appear to be an under-recognized yet common form of mixed. This is one of the first studies to examine TDP-43 and Alzheimer's disease in the context of mixed pathologies," he said.

The Brain paper built on previous research by examining whether TDP-43 was associated with an increased likelihood of a diagnosis of Alzheimer's dementia in persons both with and without pathologic Alzheimer's disease.

The findings of the study were published in the journal, Brain.