Brain scans have identified the protein tau as a better marker for Alzheimer's disease, a new study has found.
Alzheimer's disease may be determined by looking at two brain changes: the presence of amyloid beta plaques and the abnormal processes in a protein called tau.
While these two features are considered to be the hallmark signs of the disease, researchers have mainly focused on the accumulation of amyloid plaques simply because of lack effective strategies for detecting tau.
Now, experts have come up with an imaging agent called T807 that makes tau proteins detectable in positron emission tomography (PET) scan. Through this, the team was able to determine that tau proteins are better markers of cognitive decline in Alzheimer's disease patients compared to amyloid plaques.
For the study, the researchers enrolled 10 patients with mild Alzheimer's disease and 36 controls with normal cognition. Aside from brain scan, some of the study subjects were also examined using different assessment tools such as conventional clinical dementia rating (CDR) scale, spinal fluid test, pen and paper memory test.
"Our work and that of others has shown that elevated levels of amyloid beta are the earliest markers of developing Alzheimer's disease," says senior author Beau M. Ances.
Ances explains that during the early phases of the disease, patients who have an amyloid buildup in brain scans still exhibit normal cognition and intact thought process. Therefore, they suspect that amyloid changes occur first, followed by tau changes. When the combination of the two develops simultaneously, that is the time that patients start to manifest cognitive deficiencies.
The spinal fluid test is also important, but it does not provide information about the area of the brain where changes are already occurring. With imaging agents, scientists may also be able to evaluate the effectiveness of therapies in relation to the buildup of proteins in the brain.
T807 is recognized for clinical research and someday, may be used to examine other brain disorders involving excessive tau accumulation such as traumatic brain injury.
In a 2014 study, researchers were able to discover that soldiers who have had traumatic brain injury were most likely to develop cognitive problems and suffer an early death. What is more, these people are also at risk of developing dementia two years earlier than their counterparts.
One of the study authors said that even if the exact cause of this discovery remains unknown, the brain is believed to be more vulnerable to dementia when it has already been exposed to injuries.
New Discovery To Enhance Prevention
Alzheimer's disease is usually diagnosed during the latter part of the disease when signs and symptoms are already obvious and functional capabilities are already lost. With this, the researchers want to develop strategies to diagnose the disease early and to create treatments that can work against amyloid and tau accumulation.
Ances believes that even if Alzheimer's disease cannot be cured yet at present, delaying it by 10 to 15 years will make a big difference to patients, families, communities and nations.
The study was published journal Science Translational Medicine on May 11.