Early biomarkers of progressive and irreversible diseases like Alzheimer’s disease (AD) are vital. The hippocampus is a structure heavily implicated in early AD pathology but is not a heterogenous structure. Segmentation of the hippocampus, into head, body and tail along the longitudinal axis, or into subfields, may help our understanding of prodromal AD. This study employed MRI to investigate brain changes in individuals with subjective cognitive decline (SCD) and mild cognitive impairment (MCI), compared to healthy controls. Subregion volume was measured, along with T2 relaxation time to investigate tissue integrity. No measurable differences were found between those with SCD and healthy controls, but groupwise differences were found in those with MCI compared to those without. These differences were found in CA1, dentate gyrus and subiculum volumes, as well as whole hippocampus, and CA1, CA3, dentate gyrus and subiculum T2 distributions, again as well as whole hippocampus. When classifying these groups, subiculum volume and T2 emerged as the best at distinguishing those with MCI from those without. Using data from a year follow- up session, it was found that volumes and T2 distribution related to cognitive score at baseline, but neither were able to predict decline that had occurred by the following year. Overall segmentation does not seem justifiable for use on diagnosis but using segmentation in combination with T2 relaxometry and potentially functional connectivity could tell us about small changes in tissue pathology in the early stages of AD. The importance of the hippocampal head should be investigated over a longer time period.
|Date of Award||24 Mar 2020|
- The University of Bristol
|Supervisor||E J Coulthard (Supervisor) & Risto Kauppinen (Supervisor)|