PhD Oral Exam - Ariel Patricia Boyle, Psychology

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.

Abstract

Major depressive disorder (MDD) is a burdensome and prevalent condition associated with functional impairment and increasing societal costs. Despite effective treatments, relapse and chronicity rates remain high. This dissertation aims to examine the cognitive and emotional factors that may increase vulnerability to depressive symptoms across distinct high-risk contexts. Specifically, it examines how intolerance of uncertainty (IU) and fear of depression recurrence (FoDR) influence psychosocial functioning and mental health, both during periods of acute stress and during MDD remission, and the possible mechanisms by which this occurs.

In study one, data collected from 207 adults across three timepoints of the COVID-19 pandemic (each three months apart) were used to examine how depressive symptoms were influenced by pandemic-related impacts, perceived stress, and IU. Occupational disruptions predicted higher perceived stress, in turn predicting worse depressive symptoms. Contrary to prediction, persons with high IU were less affected by occupational disruptions than those with low IU, suggesting that high IU is associated with perceived stress and subsequent depressive symptoms irrespective of acute stressors.

In study two, we examined how FoDR may relate to residual symptom severity over time, and whether this occurs through daily negative mood and poor interpersonal functioning. Ninety-nine adults with remitted MDD completed questionnaires and a five-day ecological momentary assessment (EMA) of interpersonal functioning and mood at three timepoints one month apart. Increasing FoDR over time was associated with worsening mood and depressive symptoms in parallel, and higher FoDR prospectively predicted increasing depressive symptoms over time. However, FoDR was not associated with social functioning.

In study three, we examined how FoDR relates to engagement in health behaviors, and whether health behaviors may mediate FoDR's effects on depressive symptoms. Ninety-eight adults with remitted MDD completed questionnaires assessing FoDR, depressive symptoms, eating behaviors, and physical activity, along with a five-day EMA of sleep, at three timepoints one month apart. Worsening FoDR over time was associated with worse sleep quality in parallel, and sleep quality mediated the associations between FoDR and depressive symptoms. Thus, poor sleep quality might be a mechanism explaining how high FoDR increases the risk for recurrence in persons with remitted MDD. Additionally, higher baseline FoDR predicted greater uncontrolled eating at baseline and less engagement in moderate physical activity over time.

Overall, these findings underscore the relevance of IU and FoDR as cognitive vulnerabilities for depressive symptoms during periods of stress-whether due to a global crisis or the possibility of future MDEs. The findings offer insight into cognitive targets for promoting resilience and wellbeing during remission from MDD.