Hippocampal Diffusion Tensor Imaging in Parkinson's Disease and Associations with Non- Motor Symptoms

  • Author / Creator
    Budd, Alexandra
  • Parkinson’s disease (PD) is the second most common neurodegenerative disorder and causes not only well-characterised motor symptoms, but also a host of non-motor symptoms that greatly impact quality of life. PD exists within a larger spectrum of disorders caused by the accumulation of Lewy bodies within the brain. This spectrum also includes Dementia with Lewy Bodies (DLB), and different cognitive subtypes of PD, such as PD with mild cognitive impairment (PD-MCI) and PD with dementia (PDD). There is still much to be learnt about non-
    motor symptoms and progression in the brains of patients with diseases within the Lewy body spectrum. One region of the brain that may be implicated in non-motor symptoms is the
    hippocampus, which is a site that develops marked pathology as the disease spreads through the brain. However, few studies prior to this time have been able to investigate the microstructure of the hippocampus in PD and DLB patients in vivo, making it difficult to characterize ongoing non-motor symptoms and their relationship to non-motor symptoms in living patients.

    Recently, a novel diffusion tensor imaging (DTI) technique has been developed to allow high resolution diffusion imaging of the hippocampus. In this project, high resolution imaging was used to first investigate hippocampal changes in 38 patients with Lewy body spectrum diseases relative to 40 healthy older adult controls. After an initial visual inspection of the hippocampi and counting of the hippocampal digitations, no overt differences between groups were apparent. Next, we determined the association between hippocampal measures and non-motor symptoms in participants with PD and DLB. We found that fractional anisotropy (FA), but not mean diffusivity (MD) or volume (as derived from DTI), was altered in the hippocampus of patients with PD and DLB, and that FA was decreased in patients with PD and DLB when compared to controls. Furthermore, diffusion measures were correlated with age, with FA and volume decreasing and MD increasing with age as expected, but not all results were statistically significant across groups. In participants with PD and DLB, we found that patients with worse depression or sleep disturbances had higher FA than those who were less affected.

    Using the new improved method of DTI for imaging the hippocampus has allowed a more in-depth look into the hippocampal structure of living patients with PD and DLB. However, further studies are needed to understand the reasons for the direction of diffusion changes uncovered. Further studies that examine the relationship between non-motor symptoms in regions and diffusion changes beyond the hippocampus proper are also needed.

  • Subjects / Keywords
  • Graduation date
    Spring 2023
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.