PhD Oral Exam - Sana Rehan, Psychology

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.

Abstract

Both sensory and psychosocial deficits are associated with cognitive decline and Alzheimer’s disease (AD). This dissertation explores interactions between sensory, psychosocial, and cognitive functioning in cognitively healthy controls and individuals with mild cognitive impairment (MCI) and AD using cross-sectional data from the COMPASS-ND study of the Canadian Consortium of Neurodegeneration in Aging.

Study 1 examined associations between psychosocial (depressive and anxiety symptoms, social support, and social engagement) and cognitive measures (memory, executive function, processing speed, working memory, verbal fluency) in individuals with MCI. Regression analyses showed that low social participation was associated with poorer verbal fluency and slower processing speed compared to normal or high participation, suggesting that social participation may offer cognitively stimulating opportunities that support these abilities in at-risk individuals.

Study 2 characterized sensory (speech-reception thresholds, contrast sensitivity) and psychosocial (depression, anxiety, quality of life, social support, isolation) function in controls and individuals with MCI and AD, and evaluated whether psychosocial function and diagnostic group modified sensory-cognitive associations. Participants with MCI and AD demonstrated poorer sensory and psychosocial functioning than controls. Poor psychosocial function strengthened sensory-cognitive associations in MCI and AD, suggesting that individuals with cognitive impairment and poor psychosocial functioning may be particularly vulnerable to sensory effects on cognition.

Together, these studies enhance understanding of the sensory-psychosocial-cognitive relationship in individuals with cognitive impairment and suggest that psychosocial function plays an important role in shaping sensory-cognitive associations. This work explores potential mechanisms underlying these observations and highlight implications for preventative strategies and interventions targeting sensory and psychosocial functioning.