UCSF

This dissertation explores the role of educational characteristics as a marker of cognitive resilience. Incident stroke is often accompanied by acute deficits and declines in cognitive ability as well as long-term acceleration of cognitive decline. These resulting impairments and dementia drastically affect quality of life, and patients with dementia after stroke are at increased risk of death and disability. Education has been consistently identified as a predictor of cognition after stroke, but mechanisms behind this relationship are not fully understood. One hypothesis considers cognitive resilience, suggesting that education provides individuals with cognitive tools to maintain cognitive functioning amidst a clinically meaningful amount of neurodegeneration or injury. However, studies of this relationship are hindered by a lack of universally accepted definitions of cognitive resilience. Furthermore, some studies suggest that the commonly used measure of attained education may not capture variation in cognition as well as alternative measures such as educational quality and literacy. The relationship between stroke and dementia has the potential to be used to study cognitive resilience and reserve, a critical issue in cognitive aging research. By using stroke as a well-defined and clearly diagnosed disease with a known time of event onset, studies can be conducted to assess for differences between educational subgroups and to differentiate between normal-age related decline and disease-related pathological processes. Therefore, this proposal aims to investigate the influence of educational characteristics on cognitive resilience after stroke. Chapter 1 examines memory trajectories before, at the time, and after stroke in a nationally representative sample to assess where along the development of stroke education may benefit cognition. More years of attained education was associated with a small decrease in memory decrement at the time of stroke and a slight slowing of memory decline after stroke onset. However the benefits of education lie primarily in pre-existing cognitive reserve prior to stroke, with individuals of higher attained education declining only slightly slower than individuals with lower education. Chapter 2 estimates the extent to which educational characteristics modify the effect of history of stroke on dementia risk, finding that state-level administrative school quality is a predictor of late-life dementia incidence, independently of own educational attainment. Chapter 3 investigates whether education influences individuals’ cognitive responses to markers of disease pathology in the brain, finding that contrary to previous studies, the relationship between white matter hyperintensities and cognition does not differ by level of education. Together, these studies address the gap in understanding of mechanisms behind cognitive resilience by investigating whether increases in education allow people to maintain cognitive functioning following the onset of disease, and assessing where education is most beneficial along the development of disease.