Ashleigh Parker

Topic

Earlier Detection of Alzheimer’s Disease: Investigating Brain-Based Changes in Older Adults with Subjective Cognitive Decline

Department of Psychology

Date & location

• Monday, June 17, 2204

• 3:00 P.M.

• Virtual Defence

Reviewers

Supervisory Committee

• Dr. Jodie Gawryluk, Department of Psychology, University of Victoria (Supervisor)

• Dr. Cassandra Szoeke, Department of Psychology, UVic (Member)

• Dr. Theone Paterson, Department of Psychology, UVic (Member)

• Dr. Alexandre Henri-Bhargave, Division of Medical Sciences, UVic (Outside Member) 

External Examiner

• Dr. Natalie Philips, Department of Psychology, Concordia University

Chair of Oral Examination

• Dr. Dr. Nathan Lachowsky, School of Public Health and Social Policy, UVic

   

Abstract

Alzheimer’s disease (AD) is an incurable neurodegenerative disorder with a late clinical diagnosis, which disproportionately affects women. Research in preclinical AD has begun to focus on individuals with subjective cognitive decline (SCD), who are considered earliest on the cognitive continuum between healthy aging and AD. This dissertation is comprised of three manuscripts each focused on investigating whether neuroimaging (across modalities) can detect brain-based differences between individuals with SCD compared to their healthy counterparts. Study 1 is an in-depth systematic review of neuroimaging studies on SCD. Search results identified 62 studies that examined the use of structural and/or functional neuroimaging techniques in the detection of brain-based differences between individuals with SCD and healthy controls. While significant differences were found within and across various neuroimaging modalities, inconsistencies were observed within and between studies, suggesting the need for standardized criteria and longitudinal investigations in future research. Study 2 utilized resting-state functional MRI to explore functional connectivity differences in multiple brain networks between healthy older women and those with SCD. Results revealed increased functional connectivity in the default mode network and frontoparietal network among women with SCD independent of demographic variables, lifestyle factors, and medical comorbidities. Study 3 utilized multi-modal neuroimaging approach to examine grey and white matter differences in women with SCD compared to healthy women. No significant differences were detected in grey matter volume or white matter microstructure between the two groups. The resulting findings of studies 2 and 3, revealed the detection of differences between groups in brain function but not structure. This finding suggests that women with SCD can be differentiated from healthy women, iv before any significant and irreversible brain atrophy has taken place. Together, these studies contribute to the understanding of SCD as a preclinical marker of AD. Ongoing research and advancements in the conceptualization of earlier detection of AD are expected to play an important role in the development and implementation of disease modifying interventions at the earliest possible time point, thereby reducing the devastating effects of this neurodegenerative disorder.