Abstract
Purpose
The A/T/N model is a research framework proposed to investigate Alzheimer’s disease (AD) pathological bases (i.e., amyloidosis A, neurofibrillary tangles T, and neurodegeneration N). The application of this system on clinical populations is still limited. The aim of the study is to evaluate the topography of T distribution by 18F-flortaucipir PET in relation to A and N and to describe the A/T/N status through imaging biomarkers in memory clinic patients.
Methods
Eighty-one patients with subjective and objective cognitive impairment were classified as A+/A− and N+/N− through amyloid PET and structural MRI. Tau deposition was compared across A/N subgroups at voxel level. T status was defined through a global cut point based on A/N subgroups and subjects were categorized following the A/T/N model.
Results
A+N+ and A+N− subgroups showed higher tau burden compared to A−N− group, with A+N− showing significant deposition limited to the medial and lateral temporal regions. Global cut point discriminated A+N+ and A+N− from A−N− subjects. On A/T/N classification, 23% of patients showed a negative biomarker profile, 58% fell within the Alzheimer’s continuum, and 19% of the sample was characterized by non-AD pathologic change.
Conclusion
Medial and lateral temporal regions represent a site of significant tau accumulation in A+ subjects and possibly a useful marker of early clinical changes. This is the first study in which the A/T/N model is applied using 18F-flortaucipir PET in a memory clinic population. The majority of patients showed a profile consistent with the Alzheimer’s continuum, while a minor percentage showed a profile suggestive of possible other neurodegenerative diseases. These results support the applicability of the A/T/N model in clinical practice.
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Acknowledgments
We thank all patients and volunteers for participating in this study. We thank Avid Radiopharmaceuticals (Lilly) for supplying the precursor for the manufacturing of 18F-flortaucipir.
Funding
The study has been supported by the Swiss National Science Foundation (“The Biological Basis of Cognitive Impairment due to SNAP: Studying the interplay between amyloidosis and tau-related neurodegeneration”—SNF 320030_169876) and partially supported by the Personalized Health and Related Technology Initiative (“Advanced Translational Imaging”—PHRT 2017-512).
This study is part of CoSTREAM (www.costream.eu) and received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement no. 667375.
The Centre de la mémoire at Geneva University Hospital is funded by private donors: A.P.R.A.—Association Suisse pour la Recherche sur la Maladie d’Alzheimer, Genève; Fondation Segré, Genève; Ivan Pictet, Genève; Fondazione Agusta, Lugano; Fondation Chmielewski, Genève.
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Study concept and design: Dodich, Frisoni, Garibotto. Clinical consultant and data acquisition: Mendes, Assal, Chicherio, Rakotomiaramanana, Andryszak, Sheffler, Zekry, Lovblad. Statistical analysis and data interpretation: Dodich, Festari, Ribaldi, Frisoni, Garibotto. Drafting of the manuscript: Dodich, Garibotto. All the authors contributed to the critical revision of the manuscript for important intellectual content.
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All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional research committee (Commission cantonale d’éthique de la recherche—CCER)) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. All subjects participating in this study have signed an informed consent form.
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The datasets generated during and/or analyzed during the current study are part of the Geneva Memory Clinic dataset and available from the corresponding author on founded request.
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Dodich, A., Mendes, A., Assal, F. et al. The A/T/N model applied through imaging biomarkers in a memory clinic. Eur J Nucl Med Mol Imaging 47, 247–255 (2020). https://doi.org/10.1007/s00259-019-04536-9
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DOI: https://doi.org/10.1007/s00259-019-04536-9