The behavioural, cognitive, and neural correlates of blunted physiological reactions to acute psychological stress.

Ginty, Annie T. (2012). The behavioural, cognitive, and neural correlates of blunted physiological reactions to acute psychological stress. University of Birmingham. Ph.D.

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Abstract

The overarching aim of this thesis was to better understand the behavioural, cognitive, and neural corollaries of blunted cardiovascular and/or cortisol reactions to acute psychological stress. As such, it was also concerned to further test the proposition that blunted cardiovascular and cortisol reactions to acute psychological stress are markers of an unconscious dysfunction in the motivational areas of the brain. These aims were achieved by using a mixed methods interdisciplinary approach encompassing both laboratory stress studies and secondary analyses of epidemiological datasets. Chapter 2 adduced evidence that blunted cardiovascular and cortisol reactivity was associated with a non-substance addiction, namely exercise dependence. Chapter 3 demonstrated that blunted cardiovascular and cortisol reactivity was related to disordered eating behaviour. Differences in stress reactivity between healthy controls and exercise dependent individuals or disordered eaters could not be explained by actual stress task performance, how engaged or how stressful participants found the stress task, cardio-respiratory fitness, and a number of other potential confounders. Chapters 4, 5, and 6 demonstrated that poor cognitive ability was associated with blunted stress reactivity retrospectively, cross-sectionally, and prospectively. Additionally, Chapter 6 demonstrated that blunted cardiac reactivity predicted cognitive decline over a 7 year period. Chapter 7 revealed brain activation differences between pre-determined exaggerated and blunted cardiac stress reactors during an acute stress exposure in a fMRI paradigm. Blunted cardiac reactors showed hypo-activation in the areas of the brain associated with motivation and emotion compared to exaggerated reactors. There were no reactivity group differences in subjective measures of the stressfulness and difficulty of and engagement with the stress task. Overall, the research reported in this thesis provides further evidence that blunted cardiovascular and cortisol reactions to stress are associated with a number of adverse health and behavioural outcomes and may be a peripheral marker of some form of disengagement in those areas of the brain that support motivated behaviour.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):