Study Preview
Study Title and Description
Caffeine reduces resting-state BOLD functional connectivity in the motor cortex.
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 resting-state BOLD functional connectivity in the motor cortex. |
| Author | AL Rack-Gomer,J Liau,TT Liu, |
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| Year | 2009 |
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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 examined the effect of a 200 mg caffeine dose on resting-state BOLD measures in the motor cortex. Caffeine is a commonly used neural and metabolic stimulant that readily binds to adenosine receptors, thereby competitively inhibiting adenosine activation and decreasing baseline CBF. As prior work with task-related BOLD fMRI suggests that caffeine may increase the sensitivity of the BOLD signal to stimulated neural activity, we hypothesized that caffeine would also increase the sensitivity of BOLD fluctuations to spontaneous neural activity and therefore produce an increase in resting state BOLD connectivity. |
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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: Eleven healthy volunteers participated in this study after providing informed consent. After exclusion of data from 2 subjects due to excessive motion (greater than 0.4mm root mean squared displacement), the sample consisted of 9 subjects (5 males and 4 females, ages 23 to 41 years). Participants were instructed to refrain from ingesting caffeine for at least 12 hours prior to being scanned. The estimated daily caffeine usage for each subject based on self-reports of coffee, tea, and soda consumption is presented in Table 1. The assumed caffeine contents for an 8-oz cup of coffee, an 8-oz cup of tea, and a 12-oz soda were 100 mg, 40 mg, and 20 mg respectively (Fredholm et al. 1999). Each subject participated in two imaging sessions: a caffeine session and a control session, in that order. The two imaging sessions were separated by at least 6 weeks. The caffeine session consisted of a pre-dose and a post-dose imaging section, each lasting around 45 minutes each. Upon completion of the pre-dose section, participants ingested a 200 mg caffeine pill and then rested for approximately 30 minutes outside of the magnet before starting the post-dose section. This procedure is similar to our previous protocols using caffeine (Liu et al. 2004; Behzadi and Liu 2006). The first resting-state scan of the post-dose section began approximately 45 minutes after the caffeine pill was ingested to achieve approximately 99% absorption of caffeine from the gastrointestinal tract (Fredholm et al. 1999). Control sessions used the same protocol, but without the administration of caffeine between sections, similar to the protocol used in (Perthen et al. 2008). Subjects were not given a placebo during the control session. However, for convenience, we will still refer to the two scan sections as the "pre-dose" and "post-dose" sections, even though a dose was not administered. Image acquisition: Imaging data were collected on a GE Signa 3 Tesla whole body system with an eight channel receive coil. Cardiac pulse and respiratory effort data were monitored using a pulse oximeter (InVivo) and a respiratory effort transducer (BIOPAC), respectively. |
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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 | Heart rate |
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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? | RCT |
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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 collected on a GE Signa 3 Tesla whole body system with an eight channel receive coil. Cardiac pulse and respiratory effort data were monitored using a pulse oximeter (InVivo) and a respiratory effort transducer (BIOPAC), respectively. |
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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.) | In addition to caffeine exposure (baseline and post-exposure assessment), subjects underwent a control session, but no placebo was given. |
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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) |
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| What conflicts of interest were reported? | Conflicts were not discussed, |
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| Refid | 19457356 |
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| What were the sources of funding? | This work was supported in part by a grant from the National Institutes of Health (ROINS051661). |
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Results & Comparisons
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