The effects of metal work demands on cognitive aging and dementia
Open Access
- Author:
- Hyun, Jinshil
- Graduate Program:
- Human Development and Family Studies
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- August 02, 2018
- Committee Members:
- Martin J. Sliwinski, Dissertation Advisor/Co-Advisor
Martin J. Sliwinski, Committee Chair/Co-Chair
David M. Almeida, Committee Member
Lesley A. Ross, Committee Member
Joshua M. Smyth, Outside Member - Keywords:
- cognitive aging
dementia
mental work demands
cognitive reserve - Abstract:
- As the population is rapidly aging, staying mentally sharp into old age is an increasingly important public health issue. A growing body of empirical research highlights the importance of engaging in mental activities for maintaining cognitive health in later life. Because a person’s occupation is a major source of mental activities during a large segment of an individual’s life, it is important to identify occupational characteristics that impact long-term cognitive health. The overarching goal of this dissertation was to examine the associations between mental work demands and late-life cognitive outcomes in both cognitively normal individuals and those with dementia. Using data from the longitudinal Einstein Aging Study, Aim 1 examined whether mental work demands predicted the likelihood and onset of incident dementia (N=496). To calculate dementia onset, we used three temporal anchors: birth, baseline assessment, and retirement. Results indicated that individuals with greater mental work demands showed a significantly lower likelihood of incident dementia. Further, work demands were associated with delayed onset of dementia (as indexed by time since retirement), even after controlling for education, genetic risk, and other covariates. Aim 2 examined whether mental work demands were associated with levels and rates of change in cognition among older adults without dementia (N=1,118). Cognitive change was represented using two time metrics (i.e., retirement, baseline) for aligning individual trajectories. In the “time from retirement model”, mental work demands were associated with higher levels of cognitive performance and faster rates of decline. Despite faster cognitive loss, the protective effect of mental work demands persisted for 24 years after retirement. The relationship between mental work demands and rate of cognitive change, however, was not significant in the “time from baseline” model. Overall, results from this dissertation are consistent with prior work indicating that greater mental work demands in midlife confer protective effects for late-life cognition. In addition, the seemingly paradoxical result that greater mental work demands predicted faster cognitive decline in later decades of healthy older adulthood is in line with the cognitive reserve hypothesis (Stern, 2002), such that protective factors for cognitive health are associated with delayed onset but more rapid cognitive decline afterwards. Public attention as well as individuals’ efforts should be directed to continued mental engagement through midlife into old age.