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Establishing a relationship between the effect of caffeine and duration of endurance athletic time trial events: A systematic review and meta-analysis.
Shen, JG, Brooks, MB, Cincotta, J, Manjourides, JD
Journal of science and medicine in sport. 2019;(2):232-238
Abstract
OBJECTIVES Caffeine has well-documented benefits on endurance athletic performance. Because of caffeine's ergogenic effects of reducing perceived fatigue, it is hypothesized that as duration of athletic event increases, so will the effect size of caffeine upon performance. This study aims to examine the relationship between duration of endurance athletic event and the effect size of caffeine compared to placebo for athletic performance. DESIGN A systematic review and meta-analysis of placebo-controlled trials assessing the effects of caffeine in adults performing endurance athletic events. METHODS We searched MedLine, Web of Science, and review article references published through March 2016. We performed meta-analyses on placebo-controlled trials to determine the effect of the duration of an endurance athletic event on the standardized mean difference (Cohen's d) between the caffeine and placebo groups for athletic performance. RESULTS Forty articles including 56 unique comparison groups were included. Pooled results showed a Cohen's d of 0.33 (95% CI=0.21, 0.45; p=1.00; I2=0%). The effect of the duration of athletic event was significantly associated with Cohen's d (Relative Risk: 0.005; 95% CI=0.001, 0.009; p=0.024). For a 30min increase in duration of the athletic event, Cohen's d will increase by 0.150. CONCLUSIONS This study is the first to report on the statistical finding that the effect size of caffeine increases along with the increasing duration of the time trial event. Endurance athletes may especially benefit from caffeine for performance enhancement.
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High-versus low-dose caffeine in preterm infants: a systematic review and meta-analysis.
Brattström, P, Russo, C, Ley, D, Bruschettini, M
Acta paediatrica (Oslo, Norway : 1992). 2019;(3):401-410
Abstract
AIM: Though caffeine is a consolidated treatment in preterm infants, the efficacy and safety of a higher dose have not been systematically appraised. METHODS A systematic review was conducted to compare high (loading dose >20 mg/kg and maintenance >10 mg/kg/day) versus low dose of caffeine. MEDLINE, EMBASE, Central and conference proceedings for randomised controlled trials (RCTs) and quasi-RCTs were searched. Two authors independently screened the records, extracted the data and assessed the risk of bias. RESULTS As only six RCTs enrolling a total of 816 preterm infants were included, the required information size was not reached. The loading and maintenance doses varied between 20 and 80 mg/kg/day and 3 and 20 mg/kg/day, respectively. The use of high dose had no impact on mortality (RR: 0.85; 95% CI: 0.53-1.38; RCTs = 4). However, it resulted in fewer cases of extubation failure, apnoeas and bronchopulmonary dysplasia (RR: 0.76; 95% CI: 0.60-0.96; studies = 4) and shorter duration of mechanical ventilation. The quality of the evidence was low due to imprecision of the estimates. CONCLUSION Due to imprecision, it is not possible to determine whether high-dose caffeine is more effective and safe than a low dose. High dose might improve short-term respiratory function and reduce bronchopulmonary dysplasia.
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Effect of caffeine on vestibular evoked myogenic potential: a systematic review with meta-analysis.
Souza, MEDCA, Costa, KVTD, Menezes, PL
Brazilian journal of otorhinolaryngology. 2018;(3):381-388
Abstract
INTRODUCTION Caffeine can be considered the most consumed drug by adults worldwide, and can be found in several foods, such as chocolate, coffee, tea, soda and others. Overall, caffeine in moderate doses, results in increased physical and intellectual productivity, increases the capacity of concentration and reduces the time of reaction to sensory stimuli. On the other hand, high doses can cause noticeable signs of mental confusion and error induction in intellectual tasks, anxiety, restlessness, muscle tremors, tachycardia, labyrinthine changes, and tinnitus. OBJECTIVE Considering that the vestibular evoked myogenic potential is a clinical test that evaluates the muscular response of high intensity auditory stimulation, the present systematic review aimed to analyze the effects of caffeine on vestibular evoked myogenic potential. METHODS This study consisted of the search of the following databases: MEDLINE, CENTRAL, ScienceDirect, Scopus, Web of Science, LILACS, SciELO and ClinicalTrials.gov. Additionally, the gray literature was also searched. The search strategy included terms related to intervention (caffeine or coffee consumption) and the primary outcome (vestibular evoked myogenic potential). RESULTS Based on the 253 potentially relevant articles identified through the database search, only two full-text publications were retrieved for further evaluation, which were maintained for qualitative analysis. CONCLUSION Analyzing the articles found, caffeine has no effect on vestibular evoked myogenic potential in normal individuals.
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Impact of caffeine in hepatitis C virus infection: a systematic review and meta-analysis.
Wijarnpreecha, K, Thongprayoon, C, Ungprasert, P
European journal of gastroenterology & hepatology. 2017;(1):17-22
Abstract
BACKGROUND/OBJECTIVES Hepatitis C virus (HCV) infection is one of the most common causes of cirrhosis. Several studies have linked caffeine consumption to a lower degree of liver fibrosis and inflammation among patients with chronic HCV infection, but the results were inconsistent. This meta-analysis was carried out with the aim of assessing the impact of caffeine consumption among HCV-infected patients. PARTICIPANTS AND METHODS A literature search was performed using MEDLINE and EMBASE from inception to January 2016. Studies that reported relative risks, odd ratios, or hazard ratios comparing the risk of advanced liver fibrosis or the risk of moderate to severe liver inflammation among HCV-infected patients who consumed caffeine on a regular basis versus those who did not were included. Pooled odds ratios (OR) and 95% confidence interval (CI) were calculated using a random-effect, generic inverse-variance method. RESULTS Five studies were included in the fibrosis analysis. The pooled OR of advanced liver fibrosis in HCV-infected patients who consumed caffeine on a regular basis versus those who did not was 0.48 (95% CI, 0.30-0.76, I=52%). Three studies were included in the inflammation analysis. The pooled OR of moderate to severe histologic inflammation among HCV-infected patients who consumed caffeine on a regular basis versus those who did not was 0.61 (95% CI, 0.35-1.04, I=43%). CONCLUSION Our study showed a decreased risk of advanced liver fibrosis and liver inflammation among HCV-infected patients who consumed caffeine on a regular basis. Whether consumption of caffeine plays a role in the management of HCV infection requires further investigations.
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Interventions for fatigue in Parkinson's disease.
Elbers, RG, Verhoef, J, van Wegen, EE, Berendse, HW, Kwakkel, G
The Cochrane database of systematic reviews. 2015;(10):CD010925
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Abstract
BACKGROUND Factors contributing to subjective fatigue in people with idiopathic Parkinson's disease (PD) are not well known. This makes it difficult to manage fatigue effectively in PD. OBJECTIVES To evaluate the effects of pharmacological and non-pharmacological interventions, compared to an inactive control intervention, on subjective fatigue in people with PD. SEARCH METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library); MEDLINE (via PubMed); Ovid EMBASE; EBSCO CINAHL; Ovid PsycINFO; PEDro; and the WHO International Clinical Trials Registry Platform Search Portal up to April 2015. References of included studies and identified review articles were screened for additional studies. There were no restrictions based on language, date of publication or study setting. SELECTION CRITERIA Randomised controlled trials (RCTs) that report on subjective fatigue in people with PD. DATA COLLECTION AND ANALYSIS Two review authors independently performed study selection, data collection and risk of bias assessments. MAIN RESULTS Eleven studies were eligible for this systematic review, with a total of 1817 people. Three studies included only people who experienced clinically relevant fatigue (Fatigue Severity Scale score ≥ 4 out of 7 or Multidimensional Fatigue Inventory total score > 48 out of 100), whereas all other studies did not select participants on the basis of experienced fatigue. Nine studies investigated the effects of medication (i.e. levodopa-carbidopa, memantine, rasagiline, caffeine, methylphenidate, modafinil or doxepin) on subjective fatigue. All studies were placebo controlled. There was insufficient evidence to determine the effect of doxepin on the impact of fatigue on activities in daily life (ADL) or fatigue severity (one study, N = 12, standardised mean difference (SMD) = -1.50, 95% confidence interval (CI) -2.84 to -0.15; low quality evidence). We found high quality evidence that rasagiline reduced or slowed down the progression of physical aspects of fatigue (one study, N = 1176, SMD = -0.27, 95% CI -0.39 to -0.16, I(2) = 0%). None of the other pharmacological interventions affected subjective fatigue in PD. With regard to adverse effects, only levodopa-carbidopa showed an increase for the risk of nausea (one study, N = 361, risk ratio (RR) = 1.85, 95% CI 1.05 to 3.27; high quality evidence). Two studies investigated the effect of exercise on fatigue compared with usual care. We found low quality evidence for the effect of exercise on reducing the impact of fatigue on ADL or fatigue severity (two studies, N = 57, SMD = -0.45, 95% CI -1.21 to 0.32, I(2) = 44%). AUTHORS' CONCLUSIONS Based on the current evidence, no clear recommendations for the treatment of subjective fatigue in PD can be provided. Doxepin may reduce the impact of fatigue on ADL and fatigue severity; however, this finding has to be confirmed in high quality studies. Rasagiline may be effective in reducing levels of physical fatigue in PD. No evidence was found for the effectiveness of levodopa-carbidopa, memantine, caffeine, methylphenidate, modafinil or exercise. Studies are needed to investigate the effect of exercise intensity on exercise capacity and subjective fatigue. Future studies should focus on interventions that address the maladaptive behavioural or cognitive aspects of fatigue in people with PD. Characteristics, such as severity and nature of perceived fatigue and underlying mood disorders should be considered to identify responders and non-responders when studying interventions for fatigue. The development of a core-set of self-report fatigue questionnaires with established responsiveness and known minimal important difference values will facilitate the interpretation of change in fatigue scores.
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Caffeine: cognitive and physical performance enhancer or psychoactive drug?
Cappelletti, S, Piacentino, D, Sani, G, Aromatario, M
Current neuropharmacology. 2015;(1):71-88
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Abstract
Caffeine use is increasing worldwide. The underlying motivations are mainly concentration and memory enhancement and physical performance improvement. Coffee and caffeine-containing products affect the cardiovascular system, with their positive inotropic and chronotropic effects, and the central nervous system, with their locomotor activity stimulation and anxiogenic-like effects. Thus, it is of interest to examine whether these effects could be detrimental for health. Furthermore, caffeine abuse and dependence are becoming more and more common and can lead to caffeine intoxication, which puts individuals at risk for premature and unnatural death. The present review summarizes the main findings concerning caffeine's mechanisms of action (focusing on adenosine antagonism, intracellular calcium mobilization, and phosphodiesterases inhibition), use, abuse, dependence, intoxication, and lethal effects. It also suggests that the concepts of toxic and lethal doses are relative, since doses below the toxic and/or lethal range may play a causal role in intoxication or death. This could be due to caffeine's interaction with other substances or to the individuals' preexisting metabolism alterations or diseases.
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Caffeine intake and atrial fibrillation incidence: dose response meta-analysis of prospective cohort studies.
Cheng, M, Hu, Z, Lu, X, Huang, J, Gu, D
The Canadian journal of cardiology. 2014;(4):448-54
Abstract
BACKGROUND The association between habitual caffeine intake with incident atrial fibrillation (AF) was unknown. We conducted a meta-analysis to investigate the association between chronic exposure of caffeine and the risk of AF and to evaluate the potential dose-response relation. METHODS We searched PubMed, EMBASE, and the Cochrane Library up to November 2013 and references of relevant retrieved articles. Prospective cohort studies were included with relative risk (RR) or hazard ratio and 95% confidence intervals (CIs) for AF according to coffee/caffeine intake. RESULTS Six prospective cohort studies with 228,465 participants were included. In the primary meta-analysis, caffeine exposure was weakly associated with a reduced risk of AF (RR, 0.90; 95% CI, 0.81-1.01; P = 0.07; I(2) = 73%). In subgroup analyses, pooled results from studies with adjustment of potential confounders showed an 11% reduction for low doses (RR, 0.89; 95% CI, 0.80-0.99, P = 0.032; I(2) = 30.9%, P = 0.227) and 16% for high doses (RR, 0.84; 95% CI, 0.75-0.94, P = 0.002; I(2) = 24.1%, P = 0.267) of caffeine consumption in AF risk. An inverse relation was found between habitual caffeine intake and AF risk (P for overall trend = 0.015; P for nonlinearity = 0.27) in dose-response meta-analysis and the incidence of AF decreased by 6% (RR, 0.94; 95% CI, 0.90-0.99) for every 300 mg/d increment in habitual caffeine intake. CONCLUSIONS It is unlikely that caffeine consumption causes or contributes to AF. Habitual caffeine consumption might reduce AF risk.
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Nonpharmacological interventions for ADHD: systematic review and meta-analyses of randomized controlled trials of dietary and psychological treatments.
Sonuga-Barke, EJ, Brandeis, D, Cortese, S, Daley, D, Ferrin, M, Holtmann, M, Stevenson, J, Danckaerts, M, van der Oord, S, Döpfner, M, et al
The American journal of psychiatry. 2013;(3):275-89
Abstract
OBJECTIVE Nonpharmacological treatments are available for attention deficit hyperactivity disorder (ADHD), although their efficacy remains uncertain. The authors undertook meta-analyses of the efficacy of dietary (restricted elimination diets, artificial food color exclusions, and free fatty acid supplementation) and psychological (cognitive training, neurofeedback, and behavioral interventions) ADHD treatments. METHOD Using a common systematic search and a rigorous coding and data extraction strategy across domains, the authors searched electronic databases to identify published randomized controlled trials that involved individuals who were diagnosed with ADHD (or who met a validated cutoff on a recognized rating scale) and that included an ADHD outcome. RESULTS Fifty-four of the 2,904 nonduplicate screened records were included in the analyses. Two different analyses were performed. When the outcome measure was based on ADHD assessments by raters closest to the therapeutic setting, all dietary (standardized mean differences=0.21-0.48) and psychological (standardized mean differences=0.40-0.64) treatments produced statistically significant effects. However, when the best probably blinded assessment was employed, effects remained significant for free fatty acid supplementation (standardized mean difference=0.16) and artificial food color exclusion (standardized mean difference=0.42) but were substantially attenuated to nonsignificant levels for other treatments. CONCLUSIONS Free fatty acid supplementation produced small but significant reductions in ADHD symptoms even with probably blinded assessments, although the clinical significance of these effects remains to be determined. Artificial food color exclusion produced larger effects but often in individuals selected for food sensitivities. Better evidence for efficacy from blinded assessments is required for behavioral interventions, neurofeedback, cognitive training, and restricted elimination diets before they can be supported as treatments for core ADHD symptoms.
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Habitual coffee consumption and risk of heart failure: a dose-response meta-analysis.
Mostofsky, E, Rice, MS, Levitan, EB, Mittleman, MA
Circulation. Heart failure. 2012;(4):401-5
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BACKGROUND There have been discrepant findings on the association between coffee consumption and risk of incident heart failure. METHODS AND RESULTS We conducted a systematic review and a dose-response meta-analysis of prospective studies that assessed the relationship between habitual coffee consumption and the risk of heart failure. We searched electronic databases (MEDLINE, Embase, and CINAHL) from January 1966 through December 2011, with the use of a standardized protocol. Eligible studies were prospective cohort studies that examined the association of coffee consumption with incident heart failure. Five independent prospective studies of coffee consumption and heart failure risk, including 6522 heart failure events and 140 220 participants, were included in the meta-analysis. We observed a statistically significant J-shaped relationship between coffee and heart failure. Compared with no consumption, the strongest inverse association was seen for 4 servings/day and a potentially higher risk at higher levels of consumption. There was no evidence that the relationship between coffee and heart failure risk varied by sex or by baseline history of myocardial infarction or diabetes. CONCLUSIONS Moderate coffee consumption is inversely associated with risk of heart failure, with the largest inverse association observed for consumption of 4 servings per day.
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Cognition enhancement by modafinil: a meta-analysis.
Kelley, AM, Webb, CM, Athy, JR, Ley, S, Gaydos, S
Aviation, space, and environmental medicine. 2012;(7):685-90
Abstract
INTRODUCTION Currently, there are a number of pharmaceuticals available that have potential to enhance cognitive functioning, some of which may ultimately be considered for such use in military operations. Some drugs with potential for cognition enhancement have already been studied for use in military operations specific to their primary effect in sleep regulation (i.e., dextroamphetamine, modafinil, caffeine). There is considerable information available on many of these drugs. However, considerations for military appropriateness must be based on proficient research (e.g., randomly controlled trial design). METHODS A meta-analysis was conducted to summarize the current state of knowledge of these potentially cognition-enhancing drugs. The analysis only included studies which met inclusion criteria relevant to military research. RESULTS The results of the literature review reveal a gap in research of the enhancement properties of the drugs of interest. The results yielded three studies (all of which studied modafinil) that met the criteria. The meta-analysis of these three studies revealed a relatively weak pooled effect of modafinil on some aspects of cognitive performance in normal, rested adults. DISCUSSION While the results of this study support the efficacy of modafinil, the main finding is the large literature gap evaluating the short- and long-term effects of these drugs in healthy adults.