A team of scientists has successfully tracked the progression of Alzheimer’s disease using PET scans. Their groundbreaking study paves the way for a new diagnostic tool and sheds more light into how amyloid and tau work together to spur on the destructive disease.
Learn more about this study and its potential impact on the future of Alzheimer’s.
Diagnosing Alzheimer’s from Brain Scans
Researchers at the University of California at Berkeley have successfully used PET scans to track the stages of Alzheimer’s. The research team, led by William Jagust, professor at UC Berkeley’s School of Public Health and at the Helen Wills Neuroscience Institute, evaluated positron emission tomography (PET) scans of 53 adults from ages 20-77. Of the 53 adults, 5 were aged 20-26 and considered cognitively normal, 33 were aged 64-90 and were healthy while 15 were aged 53-77 and had been diagnosed with probable Alzheimer’s.
Using the stages of tau progression established by German scientists Heiko and Eva Braak, researchers from UC Berkeley were able to determine the progression of amyloid, tau and Alzheimer’s from brain scans. Jagust is encouraged by the team’s findings, stating:
“Braak staging was developed through data obtained from autopsies, but our study is the first to show the staging in people who are not only alive, but who have no signs of cognitive impairment. This opens the door to the use of PET scans as a diagnostic and staging tool.”
The study was recently published in the journal Neuron.
Gaining Insight into Amyloid and Tau Protein Deposits in Alzheimer’s
In addition to opening the door to a new diagnostic tool that can diagnose Alzheimer’s from brain scans, the research team also shed more light on the relationship amyloid and tau have in the progression of the disease. For many years, researchers believed that the buildup of beta amyloid was the root cause of Alzheimer’s. Only over the past 10 years have scientists identified tau as another major player in the development of Alzheimer’s.
Through the PET scans done by researchers at UC Berkeley, they were able to confirm that as a person aged, tau accumulation increased in the memory center of the brain. Co-lead author on the study Micheal Schöll said that:
“Tau is basically present in almost every aging brain. Very few old people have no tau. In our case, it seems like the accumulation of tau in the medial temporal lobe was independent of amyloid and driven by age.”
It is still unclear why some people have high levels of tau but never go on to develop Alzheimer’s.
Researchers believe that the amyloid and tau may work together to spur Alzheimer’s on although the exact relationship is still unclear. Jagust summarized the relationship between the two by saying, “Amyloid may somehow facilitate the spread of tau, or tau may initiate the deposition of amyloid. We don’t know. We can’t answer that at this point. All I can say is that when amyloid starts to show up, we start to see tau in other parts of the brain, and that is when real problems begin. We think that may be the beginning of symptomatic Alzheimer’s.”
Using PET Scans to Identify the Role of Tau in Alzheimer’s
A new study led by Dr. Beau Ances from Washington University in St. Louis is now also using PET scans to learn more about the role of beta-amyloid and tau in the progression of Alzheimer’s. The new scans allows researchers to watch these toxic proteins interact and will hopefully lead researchers to an effective treatment method that stops Alzheimer’s.
From PET scans, researchers have found that the tau protein is a better indicator of a person’s cognitive decline. The small study, published in Science Translational Medicine, evaluated brain scans from 10 people with mild Alzheimer’s and 36 healthy adults. They then compared the patterns of the toxic proteins and the results of standard memory tests, finding that tau tangles in the temporal lobe of the brain were strongly linked to cognitive impairment.
Ances stated, “It’s a location, location, location kind of business. The plaque starts setting up the situation, and tau is almost the executioner.”
Researchers admit that given the small size of their study, more research needs to be done to confirm the suspected role of tau in Alzheimer’s, but are also optimistic about the use of PET scans to understand more about the disease, hopefully leading to a treatment. Maria Carrillo, chief science officer of the Alzheimer’s Association is encouraged stating:
“This is exactly the type of information we’re going to need. It’s cool to see the utility of this new imaging technology actually being deployed and used.”
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