Accelerated cognitive ageing (ACA) is a phenomenon in which patients suffer from a faster decline in cognitive capacity as compared to cognitive decline caused by normal/typical ageing. In fact, people with ACA tend to have an older brain in respect of cognitive functions than their aged-matched healthy peers. This brain disorder is mainly diagnosed in patients with epilepsy. However, it does not occur in all patients growing old with epilepsy, and does not seem to be a specific syndrome from a specific type of epilepsy. ACA is rather diagnosed in patients with an already damaged brain prior or after the diagnosed status epilepticus — the non-epileptic hit being caused by traumatic brain injuries or cardiovascular comorbidities for example. Therefore we hypothesized that the structural brain might be affected and lead to physiological impairments in white matter functions, as well as in the blood perfusion properties.
The ACA is currently investigated by psychologists, radiologists and researchers, in order to find neurological origins or effects of such a cognitive decline. Discrepancies could be found in the structural brain, since cognitive decline seem to be linked to myelination (white matter integrity), the brain vascular system (structure and perfusion capacity), and maybe the cortical (grey matter) thickness.
The project aims at investigating these possible MR-descriptors of an ACA brain. The project is part of the multidisciplinary program called Neu3ca (http://neu3ca.org/), which aims at imaging, diagnosing, and treating such brain neurodegenerative disorders that affect the ageing brain.
Image courtesy of J. Conklin et al., Validation of a Simplified Model for Intravoxel Incoherent Motion Perfusion Imaging of the Brain, AJNR Am J Neuroradiol. (2016) 1–7. doi:10.3174/ajnr.A4929
One of our hypotheses is that ACA can be described by subtle changes in perfusion physiology of the brain, and/or its white matter integrity, i.e., density and water diffusion properties of the white matter. To extract quantitative measurements of white matter integrity, diffusion weighted imaging (DWI) scans are acquired from 15 ACA patients with epilepsy and 15 healthy age- and IQ-matched healthy controls. Intra-voxel incoherent motion (IVIM) imaging scans are also acquired for blood brain perfusion mapping.
Using the aforementioned imaging techniques and neuroimaging software, the student will extract apparent diffusion coefficient (ADC), fractional anisotropy (FA) maps, and perfusion parameters (such as the perfusion fraction f within a given voxel), and try to correlate them with psychological assessment scores.
The research question is the following. How do white matter and blood perfusion parameters of the brain relate to cognitive decline and ageing?