While it is now understood that long-standing hypertension is predictive of later cognitive decline and risk for dementia, little research attention to date has focused on whether the short-term dynamics of blood pressure exert immediate influence on cognitive functioning. The present study contributes to this growing field with a conceptual replication and extension of work by Gamaldo, Weatherbee and Allaire (2008). A sample of 27 older adults (M=70.2 years) completed daily assessments of blood pressure, psychological stress and cognitive functioning for 14 consecutive days. Multilevel models conditional on demographic factors were applied to simultaneously estimate between- and within-person effects across three metrics of blood pressure (systolic, diastolic and pulse pressure) and five measures of cognitive functioning. To follow a suggestion proposed by Gamaldo et al., the model was extended to include main effect and blood pressure interaction terms for stress at both levels. In secondary analyses, within-person mediation models were applied to explore blood pressure as a mediator between stress and cognition. Results from the first model demonstrated a direct, positive association between occasion diastolic pressure and episodic memory. A cross-level interaction term revealed that processing speed was impaired on high-diastolic pressure days for those with high diastolic pressure on average. We found no evidence that occasion blood pressure mediated the association between stress and cognition. Overall, our results align with the hypothesis that age-related changes to vascular structures impair the carrying capacity of blood vessels and that occasions of increased blood pressure provide additional force to overcome these limitations, delivering larger quantities of blood and oxygen to cerebral tissue. We conclude that upward fluctuations in diastolic pressure may be cognitively beneficial for older adults; diastolic pressure is the most sensitive metric for detection of within-person associations with cognition; and episodic memory and processing speed exhibit sensitivity to occasion blood pressure levels. / Graduate

Objective: This dissertation was undertaken to explore the clinical utility of physiological and behavioural metrics of neurocognitive adaptability in the screening of older adults for possible early signs of pathological cognitive aging. Methods: This was an intensive, multi-method study of 44 healthy (non-demented) Victoria-area older adults (ages 65 to 80 years). Study 1 examined timescale-specific differences in resting electroencephalographic (EEG) adaptability as a function of subtle cognitive decline. Study 2 described differences in retest practice effect -- within and across a burst of 4 to 6 occasions of computerized cognitive testing -- with respect to individual variation in estimated premorbid function and self-reported conscientiousness. Study 3 considered whether practice effects from Study 2 were related to individual differences in the resting EEG marker derived in Study 1, above and beyond the differences due to premorbid function and conscientiousness. Results: Study 1 revealed that older adults with neuropsychological performance indicators of subtle cognitive decline also showed subtle, timescale-specific differences in resting EEG adaptability. Study 2 illustrated the differentiable effects of individual differences in estimated premorbid function and conscientiousness on within- and across-occasion improvement on a computerized attention-shifting (switch) task. Study 3 demonstrated the unique promotional effects exerted by conscientiousness and resting EEG adaptability on the rate of across-occasion improvement in cognitive performance. Conclusions: Useful yet under-used tools for detecting early signs of neurocognitive decline include rigorous, standardized neuropsychological diagnostic criteria, the magnitude of practice-related improvement in cognitive performance, and characteristics of the brain's resting electrical activity. Future multi-method, ecologically-situated studies are needed to establish standardized protocol that can be used to screen growing worldwide numbers of older adults for losses in neurocognitive adaptability that may herald the earliest stages of pathological neurocognitive aging. / Graduate

The study of well-being has a long history of investigation from a nomothetic (between-person) perspective that aimed to understand characteristic levels of well-being and individual difference variables that account for stable differences across people. Recent investigations have demonstrated that levels of well-being have the capacity to rapidly fluctuate within people over short intervals and also exhibit slower changes over longer intervals, highlighting the importance of considering the ideographic (within-person) nature of well-being. The aim of this dissertation was to help build on such within-person understanding by demonstrating how theories of well-being may be empirically evaluated using innovative research designs (e.g., intensive repeated measurement designs) and analytic techniques (e.g., multilevel structural equation models [MSEM]) that can fully capture the complexity and dynamic nature of well-being. Three distinct research studies employing intensive repeated measurement designs and an MSEM analytic framework addressed a variety of research questions concerning intra- and inter-individual predictors of well-being. Study one (Chapter 2) simultaneously examined the multilevel moderation and mediation effects of cognitive interference on stress reactivity estimated in a 14-day daily diary design. Study two (Chapter 3) utilized measurement burst data from a large U.S. sample of adults, assessed across multiple time-scales, to examine long-term changes in short-term within-person associations. Random within-person slopes were specified as exogenous predictor variables of individual differences in global levels of psychological well-being. Study three (Chapter 4) used simulation data to examine the conditions where specifying within-person measurement scales as latent variables compared to unit-weighted composite scores optimized detection of within-person effects. This dissertation demonstrates the importance of innovative design and analysis to appropriately model and understand the complex, dynamic associations that operate within and across individuals in predicting their experiences of well-being. / Graduate / 2019-05-14