Kristell Pothier1,2, Laure Saint-Aubert3,4, Claudie Hooper5, Julien Delrieu5,4, Pierre Payoux3,4, Philipe de Souto Barreto5,6, Bruno Vellas5,6. 1. Gérontopôle de Toulouse, Centre Hospitalo-Universitaire de Toulouse (CHU Toulouse), Toulouse, France. kristell.pothier@univ-tours.fr. 2. EA 2114, Département de Psychologie-Psychologie des Ages de la Vie et Adaptation, University of Tours, 3, Rue des Tanneurs, 37041, Tours Cedex 1, France. kristell.pothier@univ-tours.fr. 3. Department of Nuclear Medicine, Imaging Pole, Toulouse University Hospital, Toulouse, France. 4. Toulouse NeuroImaging Center, Université de Toulouse, Inserm, UPS, Toulouse, France. 5. Gérontopôle de Toulouse, Centre Hospitalo-Universitaire de Toulouse (CHU Toulouse), Toulouse, France. 6. UMR INSERM 1027, University of Toulouse III, Toulouse, France.
Abstract
BACKGROUND: Observational and interventional studies addressing the link between amyloid (Aβ) burden and cognitive decline are increasing, but a clear definition of amyloid positivity is still lacking. This may represent a great stake for therapeutic studies enrolling Aβ + patients only. The main objective of this study was to define a population with "equivocal" amyloid status, and evaluate their cognitive changes. METHODS:Sixty-five participants over 75 years old, from the Control group of the interventional MAPT study, at risk to develop Alzheimer's disease, were included. Participants were classified into three groups in terms of amyloid load: Aβ +, Aβ - and Equivocal participants (according to visual reading, global standardized uptake (SUVR) cut-offs, or a k-mean clustering method). The cognitive changes over time (memory, executive functions, attention and processing speed) of this Equivocal group were then compared to Aβ + and Aβ - participants. RESULTS: When classified by visual read, Equivocal participants' memory scores were comparable to the Aβ- participants, and greater than in Aβ + participants over time. Secondary analyses, using SUVR cut-offs classification, showed different trajectories with Equivocal participants being comparable to the Aβ + participants, and lower than Aβ-, on executive performance over time. CONCLUSIONS: This original work pointed out a population that may be of great interest for interventional studies, raising the question of how amyloid status should be defined and integrated in such studies. These findings should be replicated in future studies on larger datasets, to confirm what methodological approach would be the most suitable to highlight this specific neuroimaging entity.
RCT Entities:
BACKGROUND: Observational and interventional studies addressing the link between amyloid (Aβ) burden and cognitive decline are increasing, but a clear definition of amyloid positivity is still lacking. This may represent a great stake for therapeutic studies enrolling Aβ + patients only. The main objective of this study was to define a population with "equivocal" amyloid status, and evaluate their cognitive changes. METHODS: Sixty-five participants over 75 years old, from the Control group of the interventional MAPT study, at risk to develop Alzheimer's disease, were included. Participants were classified into three groups in terms of amyloid load: Aβ +, Aβ - and Equivocal participants (according to visual reading, global standardized uptake (SUVR) cut-offs, or a k-mean clustering method). The cognitive changes over time (memory, executive functions, attention and processing speed) of this Equivocal group were then compared to Aβ + and Aβ - participants. RESULTS: When classified by visual read, Equivocal participants' memory scores were comparable to the Aβ- participants, and greater than in Aβ + participants over time. Secondary analyses, using SUVR cut-offs classification, showed different trajectories with Equivocal participants being comparable to the Aβ + participants, and lower than Aβ-, on executive performance over time. CONCLUSIONS: This original work pointed out a population that may be of great interest for interventional studies, raising the question of how amyloid status should be defined and integrated in such studies. These findings should be replicated in future studies on larger datasets, to confirm what methodological approach would be the most suitable to highlight this specific neuroimaging entity.
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