This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Caffeine is throught to affect blood pressure and heart rate. One channel is pharmacological. Another possible channel is mediated by expectations: because individuals expect caffeine to increase, e.g., blood pressure, it does. The purpose of this study is to decompose the effect of caffeine on blood pressure and heart rate into a pharmacological component and a component driven by expectation. The more precise questions this study asks are: whether expectations have an identifiable effect on the relationship between caffeine and blood pressure and heart rate and how large is the effect of expectation relative to the pharmacological effect of caffeine? The study has a cross-over design. Health volunteers are recruited from the UVA and Charlottesville community. They are asked to visit the GCRC four times. The first two visit they are randomized to caffeine pill or placebo pill on a blinded basis. The last two times thay are given either caffeine or placebo on an unblinded basis. On each visit, blood pressure and heart rate are measured three times, at 30 minute intervals, following treatment. The pharmacological effect of caffeine is identified by comparing the outcomes of those treated with caffeine to those given with placebo during the first two visits. The expectation effect is identified by taking all subjects given caffeine on either of their first two visits, and calculating the difference between their outcomes following blinded treatment with caffeine and their outcomes following unblinded treatment with caffeine.
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