2023-08-09 11:01:24
Medicine
An imaging technique to detect Alzheimer’s more quickly
A Geneva team has observed greater diagnostic efficiency via the tau protein and is pleading for the rapid introduction of this examination into clinical routine.
PostedAugust 9, 2023, 1:01 PM
Tau imaging in Alzheimer’s disease. The figure shows a model of tau protein accumulation, obtained by comparing the tau load of patients with Alzheimer’s disease to that of healthy controls. Blue-white color scale indicates more pronounced tau loads, with pink-white areas representing where accumulation is greatest
UNIGE
Alzheimer’s disease leads to a progressive loss of memory and autonomy. It is characterized by the accumulation in the brain of neurotoxic proteins: amyloid plaque and tau protein. Evolving quietly for decades, its very early diagnosis is essential in order to intervene as early as possible in the pathological process. A team from the University of Geneva (UNIGE) and the University Hospitals of Geneva (HUG) has demonstrated that PET tau, a very recent imaging technique for visualizing the tau protein, is able to predict cognitive decline in patients , better than commonly used imaging techniques.
These results, to be read in the journal «Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association»plead for the rapid introduction of this examination into clinical routine in order to provide patients with early and individualized solutions.
At present, one of the main diagnostic tools for Alzheimer’s disease is positron emission tomography (PET or PET according to the English acronym). “PET consists of injecting patients with a weakly radioactive tracer which disappears from the body in a few hours. These elements are designed to bind to the human molecules that we want to detect, in order to make them visible”, explains Valentina Garibotto, associate professor in the Department of Radiology and Medical Informatics of the UNIGE Faculty of Medicine and Chief Physician. from the HUG Nuclear Medicine and Molecular Imaging Department, which directed this research.
Insufficient previous techniques
“Specific tracers for amyloid have been around for some time, as well as for tracking glucose metabolism, which indicates the brain’s ability to properly use its energy resources. However, Alzheimer’s disease is complex and these two techniques are not enough to provide all the answers.
Flortaucipir is a tau-binding radiotracer developed by a pharmaceutical company and approved in 2020 by the Food and Drug Administration (FDA). It makes it possible to observe its accumulation in the brain, and above all its distribution, and to precisely assess its role in the clinical manifestation of the disease.
UNIGE and HUG scientists wanted to determine which imaging modality (amyloid PET, glucose metabolism PET or the new tau PET) can better predict future cognitive decline due to Alzheimer’s disease. Some 90 volunteers were recruited from among patients at the HUG Memory Center. “Our results show that while the different PET exams were all associated with the presence of cognitive impairment, thus confirming their role as strong predictors of Alzheimer’s disease, PET tau was the best predictor of the rapidity of cognitive decline. , even without marked symptoms at the start”, summarizes Cecilia Boccalini, doctoral student in Professor Garibotto’s team and first author of the study.
Amyloid plaques are not necessarily accompanied by cognitive loss or memory loss. However, the presence of tau always goes hand in hand with clinical symptoms. Its absence or presence is the main determinant of the stability of the state of a sick person, or on the contrary of its rapid deterioration. However, its visualization by imaging techniques has been more complicated to develop, in particular because of its lower concentration and its particularly complex structure.
Promising drugs
“This advance is decisive for better management of Alzheimer’s disease. Recently, drugs targeting amyloid have shown positive results. New treatments targeting the tau protein also seem promising. By managing to detect the disease as early as possible, before the brain is too damaged, and thanks to new treatments, we really hope to be able to make a difference in the future and for the quality of life of patients, ”underlines Valentina Garibotto. “Similarly, we are beginning to map the distribution of tau to understand how its localization to different regions of the brain influences symptoms.”
Indeed, the causes and the different stages of the disease turn out to be much less uniform than previously thought and individual susceptibility to the same phenomena must be better understood. These results therefore strongly plead for the integration of PET tau in routine clinical examinations in order to assess the individual prognosis and to select the most appropriate therapeutic strategy for each patient.
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