Graduation Year

2014

Document Type

Campus Only Senior Thesis

Department

W.M. Keck Science Department

Second Department

Biology

Reader 1

Marion Preest

Reader 2

Jessica Malisch

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Terms of Use for work posted in Scholarship@Claremont.

Rights Information

© 2014 Hannah E. Moore

Abstract

Caffeine, one of the most commonly consumed substances worldwide, acts as a biogenic stressor and elicits both cardiovascular and endocrine stress responses. The most commonly described endocrine stress response is the hypothalamic-pituitary-adrenal (HPA) axis, whose final product is cortisol. Cortisol is well described as an indicator of stress levels, and it may be elevated chronically in persistently stressful situations. Its subsequent effects include blood pressure elevation, which is an indicator of cardiovascular stress reactivity. Research shows that cardiovascular and endocrine stress responses attenuate—albeit incompletely—with habitual caffeine consumption. However, when caffeine consumption and situational stressors are combined, stress reactivity is potentiated, raising concerns about long-term effects in populations who are regularly exposed to both.

Numerous sex-related factors complicate this area of research in female cohorts. Endocrine considerations, especially relating to fluctuating estradiol levels, are well known to affect both caffeine metabolism and stress reactivity. Prior studies, ranging from biochemical to epidemiological levels, have identified variability in caffeine metabolism and stress reactivity attributable to menstrual cycle phase and recent pregnancy. Cardiovascular stress reactivity patterns differ, furthermore, between males and females, a reality that translates to differences in cardiovascular disease risk and forms a critical area of future research with broad public health implications.

Based on extensive review of caffeine metabolism and stress reactivity literature, focusing on studies relevant to young females with varying habitual levels of caffeine consumption, I designed a study proposal to further characterize these physiological stress responses within this demographic. The core goal of the proposed study is to assess changes in plasma free cortisol concentration and blood pressure following an acute dose of caffeine (200 mg) at peak (40 min) and elimination half-life (160 min) caffeine plasma concentration time points. Average daily caffeine consumption (low, medium, or high) and menstrual cycle phase were included as additional parameters of interest in order to further characterize interactions within the selected demographic.

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