Purpose Recent research suggests that caffeine use may promote a range of adjustment difficulties among adolescents, particularly during the middle school years. The effects of caffeine are particularly concerning given the increased use of high-dosage caffeine products, such as energy drinks, among youth. We investigated the influence of caffeine use on trajectories of conduct problems among early adolescents. Daytime sleepiness was tested as mediator of caffeine's effect. Methods Hypotheses were tested with longitudinal (4 waves) data from 2,633 middle school students beginning in the Fall of sixth grade and concluding in the spring of seventh grade. All students in a single class cohort at 20 West Virginia middle schools were invited to participate. Results Controlling for family affluence and management practices and pubertal development, use of more than 100 mg of caffeine significantly predicted linear increases in conduct problems over time (Est. = 0.23, p = .015). Increases in daytime sleepiness partially mediated this effect (Est. = 0.22, p = .002). Discussion Caffeine use and daytime sleepiness are important vulnerability factors for the emergence of conduct problems.

Introduction: Caffeine is a psychostimulant possessing arousal, motor activation, and reinforcing properties, which is consumed daily by most adolescents aged 12-19 years. Although current understanding of the implications of adolescent caffeine consumption for school behaviors remains incomplete, studies have shown that in addition to acute effects of the drug, in common with other habit-forming psychoactive substances, regular use leads to physical dependence, evidenced by recurring negative withdrawal symptoms. Methods: Employing two waves of longitudinal data, we tested the prospective association between daily caffeine use and homeroom teacher-observed self-control and problem behavior in a sample of middle-school students in 20 schools in West Virginia in the United States. Caffeine was operationalized with two dichotomized variables, daily consumption of <100 mg, and daily consumption of >100 mg, versus no daily use. Gender, mother's education, family financial status, social support by primary caregiver and adults in school, and school climate, were applied as covariates in linear mixed models. Results: Daily caffeine use of >100 mg was robustly and inversely associated with self-control and positively associated with problem behavior. Conclusions: Caffeine consumption and associated withdrawal symptoms may be an important factor in problematic school behavior among adolescents. Recent advent of highly concentrated caffeine products (e.g., caffeine "shots") commonly marketed directly at youth, should give rise to concerns including consideration about limiting caffeine consumption among children and youth.

Rationale: The majority of pregnant women regularly consume caffeine, a habit-forming substance of no nutritional value for mother or baby. Objectives: To examine evidence of association between maternal caffeine consumption and childhood behavioural and neurocognitive development, and to consider the soundness of current health guidance concerning the consumption of caffeine during pregnancy. Methods: Database searches identifi ed a large pool of peer-reviewed articles, which when culled for relevance yielded a modest corpus of animal and human research for inclusion in this focussed narrative review of potential caffeine-related threats to childhood behavioural and neurocognitive development. Results: High biological plausibility of potential harm from maternal caffeine exposure indicated by early animal research is confi rmed by more recent animal studies that sought to mimic human consumption patterns. Reported negative outcomes include increased neuronal network excitability and susceptibility to seizures in offspring, and disruptions to electrophysiological activity, learning, and memory. In contrast, human observational studies have yielded inconsistent fi ndings. Some studies have reported evidence of negative behavioural and neurocognitive outcomes, including hyperkinetic disorder, attention defi cit disorder, and intelligence level in preschooland elementary-aged children. Other studies, however, reported no associations with maternal caffeine consumption for similar parameters. Conclusions: Current understanding of caffeine-related increased risk of harm for childhood development is limited due to inconsistent fi ndings from human research. However, persistent reports of possible negative outcomes indicate high priority need for further research. In the meantime, the cumulative scientifi c evidence supports advice to pregnant women and women contemplating pregnancy to avoid caffeine. Review Article Maternal caffeine consumption and childhood behavioural and neurocognitive development: A focused narrative review

On the basis of Omran's theory of epidemiological transition, Jacques Blacher and colleagues (July 30, p 530)1Blacher J Levy BI Mourad JJ Safar ME Bakris G From epidemiological transition to modern cardiovascular epidemiology: hypertension in the 21st century.Lancet. 2016; 388: 530-532Summary Full Text Full Text PDF PubMed Scopus (57) Google Scholar provocatively propose six strategies to reduce the burden of hypertensive cardiovascular disease. Notably, missing from their list are strategies to minimise blood pressure variability. In several large randomised trials, such as ALLHAT2ALLHAT Collaborative Research GroupMajor outcomes in high-risk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT).JAMA. 2002; 288: 2981-2997Crossref PubMed Scopus (5112) Google Scholar and ASCOT,3Jamerson K Weber MA Bakris GL for the ACCOMPLISH Trial InvestigatorsBenazepril plus amlodipine or hydrochlorothiazide for hypertension in high-risk patients.N Engl J Med. 2008; 359: 2417-2428Crossref PubMed Scopus (1753) Google Scholar blood pressure variability has been identified as a powerful independent risk factor for stroke and cardiovascular events.4Webb AJ Fischer U Mehta Z Rothwell PM Effects of antihypertensive-drug class on interindividual variation in blood pressure and risk of stroke: a systematic review and meta-analysis.Lancet. 2010; 375: 906-915Summary Full Text Full Text PDF PubMed Scopus (580) Google Scholar, 5Muntner P Whittle J Lynch AI et al.Visit-to-visit variability of blood pressure and coronary heart disease, stroke, heart failure, and mortality: a cohort study.Ann Intern Med. 2015; 163: 329-338Crossref PubMed Scopus (199) Google Scholar, 6Rothwell PM Howard SC Dolan E et al.Prognostic significance of visit-to-visit variability, maximum systolic blood pressure, and episodic hypertension.Lancet. 2010; 375: 895-905Summary Full Text Full Text PDF PubMed Scopus (1298) Google Scholar Of note, not all antihypertensive drugs are equally effective in reducing blood pressure variability. The ALLHAT trial5Muntner P Whittle J Lynch AI et al.Visit-to-visit variability of blood pressure and coronary heart disease, stroke, heart failure, and mortality: a cohort study.Ann Intern Med. 2015; 163: 329-338Crossref PubMed Scopus (199) Google Scholar documented blood pressure variability reduction to be best with amlodipine, followed by chlorthalidone, whereas lisinopril was much less efficacious than were the other two. Given the excessive variability, it is little surprise that stroke reduction is left to be desired in the lisinopril group. Adjustment for blood pressure variability explained the differences in stroke and coronary heart disease outcomes between amlodipine-based and atenolol-based treatment in the ASCOT trial.6Rothwell PM Howard SC Dolan E et al.Prognostic significance of visit-to-visit variability, maximum systolic blood pressure, and episodic hypertension.Lancet. 2010; 375: 895-905Summary Full Text Full Text PDF PubMed Scopus (1298) Google Scholar Increased residual systolic blood pressure variability in treated hypertension causes a high risk of vascular events.7Rothwell PM Howard SC Dolan E et al.for the ASCOT-BPLA and MRC Trial InvestigatorsEffects of beta blockers and calcium-channel blockers on within-individual variability in blood pressure and risk of stroke.Lancet Neurol. 2010; 9: 469-480Summary Full Text Full Text PDF PubMed Scopus (558) Google Scholar Similar to blood pressure variability, LDL cholesterol variability has been identified as a powerful independent predictor of death and cardiovascular events.8Bangalore S Breazna A DeMicco DA Wun CC Messerli FH Visit-to-visit low-density lipoprotein cholesterol variability and risk of cardiovascular outcomes: insights from the TNT trial.J Am Coll Cardiol. 2015; 65: 1539-1548Summary Full Text Full Text PDF PubMed Scopus (118) Google Scholar Conceivably, the sixth strategy of Blacher and colleagues',1Blacher J Levy BI Mourad JJ Safar ME Bakris G From epidemiological transition to modern cardiovascular epidemiology: hypertension in the 21st century.Lancet. 2016; 388: 530-532Summary Full Text Full Text PDF PubMed Scopus (57) Google Scholar namely the temporality of antihypertensive therapy, might also relate to blood pressure variability. The fact that renin-angiotensin-aldosterone system (RAAS) blockers and β blockers are less effective with increasing age might not be due to only diminished RAAS activity, but also to increased vascular stiffness. Rigid stiff arteries enhance blood pressure variability and are less responsive to RAAS blockade than to other agents such as calcium channel blockers. We propose that reduction of blood pressure variability should be added as a seventh strategy to the list of Blacher and colleagues', which could change hypertension therapy. FHM has consultant or advisory relationships with Daiichi Sankyo, Pfizer, Abbott, Servier, Medtronic, WebMD, Ipca, American College of Cardiology, Menarini, Relypsa, and the University of Utah. SB has consultant or advisory relationships with Daiichi Sankyo, Pfizer, Abbott, and Merck. UF and SFR declare no competing interests. From epidemiological transition to modern cardiovascular epidemiology: hypertension in the 21st centuryIn 1971, Omran formulated the theory of epidemiological transition to explain the shift in mortality and disease patterns worldwide.1 The theory begins with the major premise that mortality is a fundamental factor in population dynamics. At the beginning of time was the age of so-called pestilence and famine. Mortality was high; life expectancy around 20–30 years; and famine, injuries, and infectious diseases were common causes of death. The first transition took place around 10 000 years ago which brought the world into the age of receding pandemics. Full-Text PDF Hypertension control and cardiovascular disease – Authors' replyAs pointed out by Franz Messerli and colleagues, we did not include blood pressure variability among our therapeutic objectives for optimisation of the management of hypertension and prevention of its complications in our Viewpoint.1 Numerous epidemiological studies2 have shown blood pressure variability to be correlated with prognosis in hypertension. However, many risk factors, including age, mean blood pressure, and diabetes, are significantly associated with blood pressure variability. The questions are whether this blood pressure variability is an independent cardiovascular risk factor, and whether the attributable risk could potentially be reversed. Full-Text PDF

OBJECTIVE:Adolescent use of alcohol mixed with energy drinks (AmED) has recently received increased attention. Previous studies have established a strong link between AmED and drunkenness and suggest the importance of understanding associations with AmED use. In this study, we operationalized caffeine as daily consumption of coffee, tea, cola drinks, and energy drinks, and examined whether daily caffeine consumption relates to AmED use and drunkenness.METHOD:We used multilevel structural equation modeling (SEM) with data from the 2013 Youth in Iceland cross-sectional survey among students, ages 16-17 years, who attended all of Iceland's 31 junior colleges (N = 5,784; 75% response rate; 51% girls).RESULTS:Our primary model fit the data very well with a comparative fit index of .994 and root mean square error of approximation of .042. Of the four daily caffeine consumption variables, coffee had the strongest relationship with AmED for both girls and boys, followed by energy drink consumption. The direct relationship between the daily caffeine consumption variables and drunkenness was generally weak for both genders, but the majority of the total relationship between all daily caffeine consumption variables and drunkenness was attributable to mediation through AmED. In our primary model, AmED consumption was also very strongly related to drunkenness (standardized βs = .74-.79).CONCLUSIONS:Caffeine use among adolescents ages 16-17 years is strongly related to increased consumption of AmED, irrespective of mode of caffeine consumption. AmED is strongly and positively associated with drunkenness on both individual and school levels.

Caffeine is without a doubt the most widely used drug in the world today, consumed daily in coffee and tea, in many soft drinks, in cocoa and chocolate, and in a variety of over-the-counter and prescription medicines. Recent estimates suggest that at least 80% of the entire world’s population consumes caffeine on a regular, if not daily, basis. 1 Moreover, the popularity of caffeine in the United States appears to be growing, as demonstrated by the explosive increase in the number of specialty coffee and tea shops and by the development and marketing of a variety of new caffeinecontaining products including spring water, fruit juice, and most recently chewing gum. The ubiquity and popularity of caffeine give it a special place in popular culture. However, despite nearly 400 years of widespread use and more than 50 years of scientific and medical research, many questions remain unanswered, including the basic questions of why people enjoy caffeine so much and whether the long-term consumption of this drug has an impact on health and disease. In Understanding Caffeine , James attempts to promote a better public understanding of the drug and its effects and to correct some of the common misconceptions we have about caffeine. Jack James is one of the world’s leading authorities on the health effects of caffeine, and in this book he provides a comprehensive yet concise summary of a vast scientific and medical literature. The book presents a potentially controversial message that everyone interested in health education should hear and consider carefully. Contrary to general public opinion, which considers caffeine to be a socially accepted drug with beneficial stimulant effects and no significant hazards, James advances as his theme the proposition that caffeine is a drug of abuse that is best avoided because chronic consumers realize few if any benefits from it and suffer a variety of detrimental effects on their health and well-being. James presents the necessary background information for his arguments in several introductory chapters. He provides a brief account of the history of caffeine use and describes current patterns of consumption. James also reviews the pharmacology and toxicology of caffeine, describing how the drug travels through the body, the mechanism through which it works, and the broad range of acute effects it has on physiology both at the doses most normally ingested and at the high doses that produce acute symptoms of toxicity. He makes an important point that habitual consumers may experience quite different effects, as their bodies accommodate to the continued presence of the drug. These changes also lead to the development of a physical dependence on caffeine and a pattern of unpleasant drug withdrawal symptoms when drug use is abruptly suspended. James develops his argument that caffeine offers little benefit to the habitual consumers in a chapter on the psychopharmacology of caffeine that reviews the decades of research on how caffeine affects psychological processes including cognition and mood. Although it has long been held that caffeine enhances cognitive processes, leading to improved alertness, a faster flow of thought, and a boost in performance, 2 James’s review of the scientific literature reaches a much less favorable conclusion. He details the contradictions and inconsistencies among the many studies that have been conducted to date and points out how methodological fallibility has severely constrained the conclusions that can be drawn from them. In James’s view, the psychological effects of caffeine are subtle and sporadic at best. Moreover, James argues that caffeine does not enhance either mood or cognitive function in the habitual consumer. As James describes it, the apparent benefits that a coffee drinker experiences each morning (e.g., improved alertness and a more positive mood after drinking a cup or two of coffee) are simply the restoration of functions that were impaired because he or she was deprived of caffeine overnight and is suffering the symptoms of caffeine withdrawal. This intriguing argument illustrates the difficulties inherent in studying the effects of any drug in