Neuropsychological underpinnings of cognitive changes in Alzheimer's disease
Year: 2024
Type: dissertation
Abstract: In Alzheimer’s disease (AD), patterns of biomarkers deposition and grey matter atrophy suggest an underlying dysfunction of the default mode network (DMN) relating to white matter degeneration. The changes in white matter structural connectivity underlying the DMN along the AD continuum remain unclear. Study 1 of this thesis is a systematic review of research findings from 2019 to 2023 regarding structural connectivity changes in the DMN and whether these changes are associated with cognitive changes in different stages of AD. The review identified eight studies that investigated DMN structural connectivity changes using either tract-based or network-based approaches. There was inconsistent evidence of structural connectivity changes in mild cognitive impairment (MCI) and there was a lack of longitudinal studies on the relationship between these changes and cognitive decline. These research gaps were addressed in Study 2, a longitudinal study using empirical data and a network-based approach to examine structural connectivity changes within the DMN and between the DMN and other intrinsic networks in individuals diagnosed with MCI. The study also examined the relationship between structural connectivity changes and cognitive changes in MCI. Longitudinal diffusion tensor imaging and neuropsychological assessments were conducted with 67 participants (41 with normal cognitive ability, 26 with MCI) for up to two years. Differences in the rate of change of structural connectivity and cognitive functions were analysed with linear mixed effects models. Relationships between structural connectivity and cognitive functions were examined with hierarchical regression. Results suggested changes in structural connectivity within the DMN in connections between the right dorsolateral and left medial superior frontal gyri, and between the right angular gyrus and right inferior temporal gyrus. A decline in internetwork structural connectivity was also found between the DMN and the limbic network, and between the DMN and the visual network. Structural connectivity changes between the right dorsolateral and left medial superior frontal gyri were associated with a decline in processing speed and semantic memory. Intra- and internetwork structural connectivity of the DMN started at an early stage of AD and was associated with cognitive decline. Intranetwork structural connectivity changes in connections between the bilateral superior frontal gyri could be an important DMN segment contributing to a decline in processing speed and semantic memory in AD. Intranetwork structural connectivity decline in the temporal-parietal portion of the DMN and internetwork structural connectivity decline between the DMN and the visual and limbic networks might underlie deficits in emotion perception and regulation in AD.
Authors: Tse, Yuk Ying Michelle, 謝玉瑩
Language: English
Subfield: Psychiatry and Mental health
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7112368692