Medial Temporal Lobe Does Not Tell The Whole Story: Episodic Memory In ‘atypical’ Variants Of Alzheimer’s Disease

Loading...
Thumbnail Image
Degree type
Doctor of Philosophy (PhD)
Graduate group
Neuroscience
Discipline
Subject
Atypical variant of Alzheimer's disease
episodic memory (verbal/visual)
hippocampus/medial temporal lobe
lexical retrieval
logopenic variant of Primary Progressive Aphasia
posterior cortical atrophy
Neuroscience and Neurobiology
Funder
Grant number
License
Copyright date
2018-09-27T20:17:00-07:00
Distributor
Related resources
Contributor
Abstract

Alzheimer’s disease is the most common form of dementia, which is globally epidemic and well-known by the general public. Episodic memory, a conscious recollection of a particular event in spatial and temporal context, is the most prominent deficit in the early stage of clinical amnestic AD, and reflected by the shrinkage of structures in medial temporal lobe (MTL), including the hippocampus. According to Braak staging, tangles begin in the transentorhinal cortex of the MTL, which then spreads to hippocampal subfields, and later to neocortical areas. Cases that are less recognized by the general public are patients with the atypical variants of AD. Interestingly, many of the atypical cases of AD appear to share the same histopathological features with clinical amnestic AD. According to the diagnostic criteria for these atypical variants of AD, episodic memory should be relatively preserved. However, inconsistent reports on the episodic memory performance and the hippocampal involvement in these atypical cases pose challenges for accurately diagnosing these patients. The two kinds of atypical variants of AD that I focused here are logopenic variant of Primary Progressive Aphasia (lvPPA) and posterior cortical atrophy (PCA). The overarching theme of my thesis is to examine 1) whether the atypical cases of AD have episodic memory difficulty, and if so, 2) what brain areas are responsible for this difficulty. Chapter 2 and 3 of the current thesis show that 1) episodic memory difficulty is observed in lvPPA and PCA cases and 2) this impairment is modulated by deficit in other cognitive domains and associated with disease in non-MTL brain regions. This would be consistent with the ‘hippocampal-sparing’ hypothesis that not all AD histopathology begins in the MTL, and these hippocampal-sparing conditions suggest that additional mechanisms must be considered in the genesis of spreading pathology in AD.

Advisor
Murray Grossman
Joe Kable
Date of degree
2017-01-01
Date Range for Data Collection (Start Date)
Date Range for Data Collection (End Date)
Digital Object Identifier
Series name and number
Volume number
Issue number
Publisher
Publisher DOI
Journal Issue
Comments
Recommended citation