Study Preview
Study Title and Description
Caffeine reduces the activation extent and contrast-to-noise ratio of the functional cerebral blood flow response but not the BOLD response.
Key Questions Addressed
| 1 | For [population], is caffeine intake above [exposure dose], compared to intakes [exposure dose] or less, associated with adverse effects on cardiovascular outcomes? |
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Primary Publication Information
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| Title | Caffeine reduces the activation extent and contrast-to-noise ratio of the functional cerebral blood flow response but not the BOLD response. |
| Author | J Liau,JE Perthen,TT Liu, |
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| Year | 2008 |
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Secondary Publication Information
There are currently no secondary publications defined for this study.
Extraction Form: Cardiovascular Design
| Question... Follow Up | Answer | Follow-up Answer | |
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| What outcome is being evaluated in this paper? | Cardiovascular |
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| What is the objective of the study (as reported by the authors)? | We used a caffeine dose (200 mg) to decrease baseline CBF. |
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| Provide a general description of the methods as reported by the authors. Information should be extracted based on relevance to the SR (i.e., caffeine related methods) | Experimental protocol: Ten healthy adult subjects (5 males, mean age 33 years, standard deviation 7 years) participated in the study. Each experiment consisted of a pre-dose and a post-dose imaging session. In between the sessions, the subjects ingested a 200 mg caffeine pill and rested outside of the magnet for 30 minutes, similar to previous protocols using caffeine (Liu et al. 2004; Behzadi and Liu 2006). A total of 45 minutes elapsed between ingestion of the caffeine pill and the first functional scan in the post-dose session to allow for proper absorption of caffeine from the gastrointestinal tract (Fredholm et al. 1999). Image acquisition: Imaging data were acquired on a GE Signa Excite 3 Tesla whole body system with a body transmit coil and an eight channel receive head coil. Laser alignment was used to landmark the subjects and minimize differences in head position between pre-dose and post-dose sessions. The resting-state and functional scans were acquired with a PICORE QUIPSS II (Wong et al. 1998) ASL sequence (TR = 2.5 s, TI1/TI2 = 600/1500 ms) with a dual echo spiral readout (TE1/TE2 = 2.9/24 ms, FOV = 24 cm, 64 Å~ 64 matrix, and a flip angle of 90°). Six oblique axial 5-mm slices were prescribed about the calcarine sulcus for all functional runs. Cardiac pulse and respiratory effort data were monitored using a pulse oximeter (InVivo) and a respiratory effort transducer (BIOPAC), respectively. The pulse oximeter was placed on the subject’s left index finger, and the respiratory effort belt was placed around the subject’s abdomen. Physiological data were sampled at 40 samples per second using a multi-channel data acquisition board (National Instruments). |
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| How many outcome-specific endpoints are evaluated? | 2 |
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| What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) | Cerebral blood flow |
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| List additional health endpoints (separately). 2 | Cardiac pulse |
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| List additional health endpoints (separately).3 |
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| List additional health endpoints (separately).4 |
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| List additional health endpoints (separately).5 |
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| List additional health endpoints (separately).6 |
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| Clinical, physiological, other | Physiological |
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| What is the study design? | Controlled Trial |
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| Randomized or Non-Randomized? | NCT |
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| What were the diagnostics or methods used to measure the outcome? | Objective |
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| Optional: Name of Method or short description | Imaging data were acquired on a GE Signa Excite 3 Tesla whole body system with a body transmit coil and an eight channel receive head coil. Cardiac pulse and respiratory effort data were monitored using a pulse oximeter (InVivo) and a respiratory effort transducer (BIOPAC), respectively. The pulse oximeter was placed on the subject’s left index finger, and the respiratory effort belt was placed around the subject’s abdomen. Physiological data were sampled at 40 samples per second using a multi-channel data acquisition board (National Instruments). |
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| Caffeine (general) | Caffeine (general) |
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| Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other? |
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| Measured or self reported? | Measured |
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| Children, adolescents, adults, or pregnant included? | Adults |
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| What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.) | Pre-dose imaging session scans vs. post-dose imaging scans. Subjects were their own controls in this sense. |
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| What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models. Copy from methods) | We used two-tailed paired t-tests to compare pre-dose and post-dose parameter estimates. For both the CBF and BOLD data, we compared the pre-dose and post-dose values of the number of functionally active voxels (using the pre-dose and post-dose activation maps) and the contrast-to-noise ratio estimates. To assess caffeine’s effect on CBF and BOLD temporal dynamics, we used paired two-tailed t-tests to compare the pre-dose and post-dose timing parameters (T50 , TA50 , and FWHM) across subjects. In addition, to examine whether possible changes in the shape of the curve affected correlation of the responses with the GLM reference function (X ), we computed the correlation between the reference function and the per subject Δ CBF and %Δ BOLD time series. Paired two-tailed t-tests were then used to compare the pre-dose and post-dose correlation values across subjects. |
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| What conflicts of interest were reported? | Not discussed. |
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| Refid | 18514545 |
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| What were the sources of funding? | Not discussed. |
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Results & Comparisons
No Results found.
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