Browsing by Author "Chung, E-Lim Lydia Wu"

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    From stress to dementia risk: An examination of psychological, immunological, and neurobiological mechanisms underlying increased risk for Alzheimer's disease and related dementias in widow(er)s
    (2024-07-29) Chung, E-Lim Lydia Wu; Fagundes, Christopher P
    Being widowed is associated with poorer cognitive function and higher incidence rates of Alzheimer’s disease and related dementias (ADRD). The mechanisms underlying the link between spousal bereavement and ADRD risk remain relatively unexplored. Individual differences in health may be examined within a biopsychosocial framework, which posits that biological, psychological, and interpersonal factors independently and interactively affect health. For example, within the context of stress and ADRD, experiencing a significant psychological stressor, such as spousal bereavement, may be particularly detrimental for individuals who also display additional psychosocial and biological risk factors of ADRD. To understand how bereavement may enhance ADRD risk and which widow(er)s may be at heightened risk, I used psychological, immunological, and neuroimaging approaches to examine individual differences in neurocognitive health 1) between bereaved spouses and nonbereaved controls and 2) among bereaved spouses. Across 3 datasets, recently bereaved spouses and nonbereaved adults completed neuropsychological assessments, self-report questionnaires on psychosocial well-being, and provided venous blood samples for inflammatory assays. A subset of bereaved and nonbereaved adults also completed a structural magnetic resonance imaging scan for quantification of cortical thickness and provided blood samples for plasma amyloid beta assays. Widow(er)s and nonbereaved adults showed significant differences in working memory performance and brain morphology. Among widow(er)s, depressive symptoms and cortical thickness in ADRD-related brain regions were associated with several cognitive domains. The relationship between psychosocial well-being (e.g., depressive symptoms, loneliness) and cognitive inhibition depended on widow(er)s’ levels of systemic inflammation and cortical thinning in ADRD-related brain regions. Tentative relationships between inflammation, plasma amyloid, and cortical thickness were also observed. Findings suggest that differences in cognitive function and brain morphology among widow(er)s and between widow(er)s and nonbereaved adults are evident as early as the first few months of bereavement. Notably, the present study replicated patterns previously observed in the cognitive neuroscience and depression literature and identified novel, psychobiological mechanisms of neurocognitive aging. Beyond its contribution to the bereavement literature, this research broadens our understanding of the mechanisms linking stressful life events to increased disease risk.
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    Neural mechanisms underlying individual differences in daily psychological experiences and cortisol activity
    (2022-08-08) Chung, E-Lim Lydia Wu; Fagundes, Christopher P
    Cortisol, a stress hormone released from the hypothalamic-pituitary-adrenal (HPA) axis during stress, supports many vital bodily functions. Individual differences in cortisol patterns exist, and neural patterns underlying appraisal processes may contribute to these differences. In this project, I examined whether neural activation patterns to affective stimuli can explain interindividual differences in daily negative experiences and daily cortisol patterns. The analytic sample included participants from the MIDUS-2 dataset who completed an fMRI session, daily interviews, and cortisol assessments. Neural activation patterns to negative stimuli were generally unrelated to daily cortisol levels. Amygdala and dorsal PFC activity toward negative stimuli were positively related to negative psychological experiences and negatively related to positive psychological experiences. The relationship between daily psychological experiences and daily cortisol output depended on prefrontal, limbic, and paralimbic activity to negative stimuli. This study enhances our understanding of the neural mechanisms that underlie interindividual differences in daily psychobiological experiences.