Notably, PET scans revealed that younger study participants had higher overall levels of tau in their brains, as well as a stronger link between baseline tau and subsequent brain atrophy, compared to older participants. This suggests that other factors -- likely other abnormal proteins or vascular injuries -- may play a larger role in late-onset Alzheimer's, the researchers say.

Ability to Predict Brain Atrophy a 'Valuable Precision Medicine Tool'


The results add to hopes that tau-targeting drugs currently under study at the UCSF Memory and Aging Center and elsewhere may provide clinical benefits to patients by blocking this key driver of neurodegeneration in the disease. At the same time, the ability to use tau PET to predict later brain degeneration could enable more personalized dementia care and speed ongoing clinical trials, the authors say.

"One of the first things people want to know when they hear a diagnosis of Alzheimer's disease is simply what the future holds for themselves or their loved ones. Will it be a long fading of memory, or a quick decline into dementia? How long will the patient be able to live independently? Will they lose the ability to speak or get around on their own? These are questions we can't currently answer, except in the most general terms," Rabinovici said. "Now, for the first time, this tool could let us give patients a sense of what to expect by revealing the biological process underlying their disease."

Rabinovici and his team also anticipate that the ability to predict future brain atrophy based on tau PET imaging will allow Alzheimer's clinical trials to quickly assess whether an experimental treatment can alter the specific trajectory predicted for an individual patient, which is currently impossible due to the wide variability in how the disease progresses from individual to individual. Such insights could make it possible to adjust dosage or switch to a different experimental compound if the first treatment is not affecting tau levels or altering a patient's predicted trajectory of brain atrophy.

"Tau PET could be an extremely valuable precision medicine tool for future clinical trials," Rabinovici said. "The ability to sensitively track tau accumulation in living patients would for the first time let clinical researchers seek out treatments that can slow down or even prevent the specific pattern of brain atrophy predicted for each patient."

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