Etude de la réorganisation anatomo-fonctionnelle des réseaux au repos associée à la maladie d'Alzheimer

Chercheurs boursiers - Junior 1 | Concours 2012-2013

Pierre Bellec

Centre de recherche de l'Institut universitaire de gériatrie de Montréal (IUGM)


Domaine : Vieillissement

Alzheimer's disease (AD) will soon reach epidemic proportions. Initial symptoms of the disease can take many forms, which are not unique to AD. Today, clinicians will only establish a diagnosis of probable AD when patients present signs of dementia. Unfortunately, at this point, the neurodegenerative process has already severely damaged brain tissues. If we are to open new avenues for efficient interventions, clinicians need to diagnose AD at the earliest stage possible, ideally before any symptom occurs. To facilitate the diagnosis, biomarkers can be used to monitor the progress of brain deterioration: grey matter quickly gets thinner and the white matter pathways are disrupted prior to cognitive decline. State-of-the-art structural biomarkers still cannot predict accurately which individuals are at high risk for AD. A key missing piece of the puzzle is that we don't know how the brain maintains intact cognitive abilities despite the on-going neurodegenerative process. My working hypothesis is that the interactions between distant brain regions can reorganize to compensate localized structural damages. This plasticity of distributed functional networks could greatly inform us on the progress of AD and play a central role in the diagnosis. Resting-state functional MRI (fMRI) can capture the organization of brain networks by measuring the spatial coherence of spontaneous brain activity while the subject is at rest. We propose to track the plasticity of functional networks using novel fMRI analytical methods and identify the associated structural changes using dedicated biomarkers. The accuracy of a diagnosis based on fMRI will be assessed on a patient database collected over multiple sites. This project will document the interplay between functional and structural changes over the course of AD, which will lead to earlier and better diagnosis of the disease.