Tau tangles on PET scans may signal impending cognitive decline in asymptomatic individuals
New data highlight the significance of tau-positive imaging in the progression of Alzheimer’s disease.
Abnormal accumulation of tau protein—referred to as tau tangles—on PET imaging has previously been linked to neurodegeneration, much like the buildup of amyloid. However, more focus has been put on the presence of amyloid on PET scans with regard to the progression and management of Alzheimer’s, despite growing evidence that tau tangles spotted on imaging prior to diagnosis often precede the onset of cognitive decline.
Now, a new study is providing additional evidence implicating tau in the progression of Alzheimer’s. This prompted experts involved in the study to suggest that providers who spot tau tangles on PET scans in patients without cognitive decline should take proactive measures, as it could indicate a high risk of disease progression within five years.
“These findings underscore the potential role of tau PET as a biomarker for staging Alzheimer disease neuropathologic changes across the spectrum of the disease,” Alexis Moscoso, PhD, with the Wallenberg Center for Molecular and Translational Medicine at the University of Gothenburg in Sweden, and colleagues suggested.
For the study, experts compiled longitudinal data from 21 cohorts across 13 countries. This included a sample size of over 6,500 individuals with available PET imaging. The diverse dataset included cognitively unimpaired participants alongside those diagnosed with mild cognitive impairment, Alzheimer’s dementia or other neurodegenerative disorders.
Each participant had available tau PET with flortaucipir F18 and amyloid-β (Aβ) PET imaging for review. Imaging findings were compared alongside medical records to determine the relationship between tau-positive scans and progressing cognitive impairment and/or an eventual diagnosis of Alzheimer’s.
Of the nearly 3,500 cognitively unimpaired individuals, around 10% showed tau tangles on imaging. This finding was less common among participants under 50 but increased steadily with age. Tau positivity was evident in 43% and 79% of those diagnosed with mild cognitive impairment and Alzheimer’s dementia, and most (92%) of these individuals also were Aβ PET positive.
What’s more, cognitively unimpaired individuals who were positive for both tau and Aβ showed significantly higher odds of developing cognitive impairment or being diagnosed with Alzheimer’s within five years of their initial PET scan compared to those who were positive for just one or the other. This finding further emphasizes the utility of tau imaging in predicting cognitive decline and neurodegeneration, the authors suggested.
Learn more about the study results here.
In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.