Author: Yung Tsen Chen

Publisher:

Published: 2018

Total Pages: 171

ISBN-13: 9780438370494

Ageist stereotype threat can impact older adults' cognitive ability, including memory performance, but the mechanisms underlying these effects are poorly understood. In this dissertation, I used behavioral tasks, physiological measurement, and brain imaging (fMRI) to identify the mechanisms underlying ageist stereotype effects in older adults. A large sample of cognitively normal older adults (mean age = 63.6) was randomly assigned to either a stereotype activation or control group. On the first day (baseline) all participants completed episodic and working memory tasks, and on the second day I gave instructions explicitly activating aging stereotypes (or a control passage) just before they took these same tests during fMRI brain scanning. There were three primary findings. First, although there was no overall stereotype effect on working memory or episodic memory performance, regression analyses based on prior work indicated that education and retirement status moderated the impact of stereotype activation on episodic memory performance. Second, self-report measures as well as physiological measures (e.g., heart rate variability) revealed that the stereotype manipulation did not increase anxiety or stress. These and other findings indicate that stereotype activation in the fMRI environment did not cause an extreme threat or emotional response in older adults, but may have instead motivated some of them to differentially engage the tasks than others. Lastly, using whole-brain fMRI and targeted Region-of-Interest (ROI) analyses, I found that stereotype activation increased activity in the superior and middle temporal gyrus, which have previously been associated with emotion regulation, as well as posterior midline regions (e.g., mid-cingulate, posterior cingulate cortex and precuneus), which have previously been associated with processing stereotype threat and self-referential thoughts. Stereotype activation also altered functional connectivity between these regions and prefrontal regions associated with self-relevant ideas and attentional focus (e.g., anterior prefrontal cortex and orbitofrontal cortex/ventromedial prefrontal cortex). These fMRI results are consistent with a motivational shift hypothesis, or the idea that aging stereotypes cause older adults to engage self-referential thought and a prevention-focused response style (i.e., trying harder to avoid losses and prevent errors). As a whole, these results demonstrate for the first time that stereotype activation can impact neural activity in older adults, even in the absence of large behavioral effects. This work emphasizes the importance of minimizing even the mildest stereotype threat in clinical settings aiming to use fMRI to help diagnose memory problems in older adults, as a stereotyping environment can significantly impact the test results.