NCT04150198

MECHANISMS OF NEURONAL RESILIENCE IN ALZHEIMER'S DISEASE AND ITS FOCAL VARIANTS: A PET/MR STUDY

• Status: Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 45 (estimated)
• Sponsor: Institut National de la Santé Et de la Recherche Médicale, France · Other Government
• Sex: All
• Age: 40 Years – 80 Years
• Healthy volunteers: Accepted

Summary

Patients with Alzheimer's disease and with early onset of symptoms (\<65 years) (AD-Y) have a multi-domain cognitive deficit, whereas memory disorders (typical of the elderly patient's AD) are less often in the foreground. In addition, some MA-J have an atypical phenotype indicating focal brain damage, although they have the same pathological lesions: amyloid deposits and tau protein deposition (DNF). This is the case of posterior cortical atrophy (PCA) characterized by complex visual disturbances and atrophy affecting the more posterior regions of the brain. Based on the clinical profile of PCA patients, a more refined anatomo-clinical classification was proposed, distinguishing a rather "ventral" form and a rather "dorsal" form. The recent arrival of tau-specific PET tracers now makes it possible to evaluate in vivo fibrillary neurodegeneration (FND), which is well correlated with the severity of cognitive disorders. Advances in MRI have shown that each neurodegenerative syndrome targets a large-scale neural network, which in turn shows a vulnerability for a specific biological disease. In the case of AD, the reason for such a difference in cognitive and anatomical impairment between patients with diffuse involvement and others with more focal involvement is not known. One possible explanation is the existence, in focal forms, of neuronal mechanisms that oppose vulnerability. These mechanisms may correspond to the so-called "resilience" phenomenon, defined as resistance to a neuropathological process by the ability to optimize cognitive performance via the efficient recruitment of neural networks. The mechanisms underlying resilience in neurodegeneration are unknown. Their identification is very important for the management and treatment of AD.

Detailed description

Working hypotheses We hypothesize that "focal" patients (PCA) versus "diffuse" patients (AD-Y) have (i) less severe white matter involvement; (ii) effective reorganization of the functional brain networks; iii) pathologically, a different topography and lesion load. This project has no redundancy with the work already done in our team and in other teams at the international level. Expected benefits This study will highlight the neural mechanisms underlying resiliency in a group of AD patients who, although having the same disease, present with a very different clinical and cognitive profile. Demonstration of these specific mechanisms of resilience in the diseased brain is essential to better understand the pathophysiological processes of AD. We consider that the pharmacological approach and the functional reeducation to this disease depend essentially on a better knowledge of both the topographic distribution of the underlying histopathology (in particular, the tau protein), and the response capacity from the brain to these lesions (state of connection of networks, functional reorganization). In addition, when treatments for AD are available, a precise definition of phenotypic variants will be essential for the selection of patients for these therapies and for therapeutic follow-up. In the longer term, resilient neural circuits could be modulated and strengthened through transcranial stimulation. Indeed, promising results have been obtained showing that these techniques can improve the performance of altered cognitive functions in patients with dementia.

Conditions

• Alzheimer Disease, Early Onset
• Posterior Cortical Atrophy

Interventions

Type	Name	Description
DEVICE	TEP/IRM	All participants will have a PET / MRI examination including: i) a 30-minute PET scan, 80 minutes after intravenous injection of 240 MBq of 18F-AV1451 ± 10% ii) a ZTE sequence (for attenuation correction of PET images), a 3D T1 anatomical sequence, a diffusion MRI, a functional MRI at rest (total duration: 45 minutes). These acquisitions will be made during the same exam session on a hybrid PET / MRI camera allowing simultaneous acquisitions. This visit lasts about 3 hours.

Timeline

• Start date: 2021-12-08
• Primary completion: 2025-12-01
• Completion: 2026-12-01
• First posted: 2019-11-04
• Last updated: 2024-07-30

Locations

2 sites across 1 country: France