Journal of Caffeine Research

Background: Sex differences in cocaine abuse are well established. Females have a higher sensitivity and thus higher vulnerability to cocaine abuse compared to males. There are many studies showing that sensitivity to cocaine reward varies during the estrus cycle. Methods: Vaginal smears were examined through a DIFF staining kit and viewed through a microscope to determine the estrus cycle stage. Smears were taken immediately before and after cocaine and/or caffeine injections. Furthermore, we suggest a new tool to analyze the estrus cycle by using electrical resistance of the vaginal mucosa...

Caffeine consumption and cigarette smoking tend to occur within the same individuals and at the same time. One potential explanation for this co-use is that caffeine consumption increases subjective smoking reinforcement. Electronic diaries were used to collect momentary reports of smoking, caffeine consumption, temptation/urge to smoke, and subjective smoking reinforcement in 74 prequit smokers. Momentary reports of caffeine consumption and smoking were associated, replicating previous findings. These results remained significant when contextual factors (time of day, weekday/weekend, presence of others, presence of others smoking, location, and past hour alcohol consumption) were covaried...

Background: Research has reliably demonstrated that caffeine produces a general increase in physiological arousal in humans, but we previously failed to obtain the expected arousal-based changes in manually quantified event-related potential (ERP) components in response to the stimuli in a simple Go/NoGo task. Methods: A single oral dose of caffeine (250 mg) was used in a randomized double-blind placebo-controlled repeated-measures cross-over study. Adult participants (N=24) abstained from caffeine for 4 hours before each of two sessions, approximately 1 week apart...

Background: Energy drinks and energy shots are popular consumer beverages that are advertised to increase feelings of alertness. Typically, these products include high levels of caffeine, a mild psychostimulant drug. The scientific evidence demonstrating the specific benefits of energy products to users in terms of subjective state and objective performance is surprisingly lacking. Moreover, there are rising health concerns associated with the use of these products. Therefore, the purpose of this study was to investigate the acute effects of a popular energy shot (5-Hour Energy(®)) on subjective and objective measures that were assessed hourly for 6 hours following consumption...

Background: It is well known that the reinforcing properties of cocaine addiction are caused by the sharp increase of dopamine (DA) in the reward areas of the brain. However, other mechanisms have been speculated to contribute to the increase. Adenosine is one system that is associated with the sleep-wake cycle and is most important in regulating neuronal activity. Thus, more and more evidence is pointing to its involvement in regulating DA release. The current study set out to examine the role of adenosine in cocaine-induced DA release...

Objectives: The aims of this study were to evaluate patterns of circadian preferences and daytime sleepiness, and to examine the extent to which the consumption of stimulant beverages is associated with daytime sleepiness and evening chronotype among Peruvian college-age students. Methods: A total of 2,581 undergraduate students completed a self-administered comprehensive questionnaire that gathered information about sleep habits, sociodemographic and lifestyle characteristics, and the use of caffeinated beverages...

Background: Disruptive effects of caffeine on sleep have previously been reported, although measures of next-day mood and performance have rarely been included. The present study aims to evaluate the effects of caffeine on sleep and associated next-day effects in a naturalistic field setting. Methods: Nineteen participants (daily caffeine intake 0-141 mg), assessed as good sleepers, took part in a randomized, placebo-controlled, double-blind, 2-week crossover study to assess the effects of bedtime caffeine use (250 mg) on sleep and next-day cognitive performance and mood, which were assessed on a mobile phone in the morning and afternoon...

Background: Inflammation is considered to be a major initiator to angioplasty-induced vascular restenosis. Proinflammatory cytokines stimulate vascular smooth muscle cell (VSMC) migration and proliferation leading to neointimal hyperplasia. It has been reported that chronic caffeine use suppresses the production of proinflammatory cytokine TNF-α (tumor necrosis factor Alpha) and alters adenosine receptor expression in human neutrophils, indicating that caffeine may attenuate vascular injury-induced inflammation and subsequent neointimal hyperplasia...

BACKGROUND: The use of acupuncture in the treatment of pain conditions has been extensively investigated. However, the influence of dietary ingredients on acupuncture-induced analgesia (AA) remains unexplored. Recently, the role of adenosine receptors in AA has been shown, and caffeine, one of the world's most commonly consumed dietary ingredients, is an antagonist of these receptors. In this study, the postincisional pain model was used to investigate caffeine's influence on AA. METHOD: Mice submitted to plantar incision surgery were treated with acupuncture needling after administration of acute or chronic caffeine...

BACKGROUND: Soft drinks containing caffeine have been associated with more aggressive forms of dental decay. Cariogenicity of caffeinated soft drinks may be attributed to the effect of caffeine on salivary flow. This study assessed whether caffeinated soft drinks produced short-term oral dryness in healthy adults. METHODS: The authors collected saliva on two separate days from 35 participants before and one hour after drinking a soft drink. On one of the days the soft drink was caffeinated and on the other day it was not...

Caffeine is the most commonly used drug in the world. Although consumption of low to moderate doses of caffeine is generally safe, an increasing number of clinical studies are showing that some caffeine users become dependent on the drug and are unable to reduce consumption despite knowledge of recurrent health problems associated with continued use. Thus, the World Health Organization and some health care professionals recognize caffeine dependence as a clinical disorder. In this comprehensive literature review, we summarize published research on the biological evidence for caffeine dependence; we provide a systematic review of the prevalence of caffeine dependence and rates of endorsement of clinically meaningful indicators of distress and functional impairment among habitual caffeine users; we discuss the diagnostic criteria for Caffeine Use Disorder-a condition for further study included in the Diagnostic and Statistical Manual of Mental Disorders ( 5th ed ...

Current regulation of caffeine-containing products is incoherent, fails to protect consumers' interests, and should be modified in multiple ways. We make the case for one of the regulatory reforms that are needed: all consumable products containing added caffeine should be required by the Food and Drug Administration (FDA) to include caffeine quantity on their labels. Currently, no foods or beverages that contain caffeine are required to include caffeine content on their labels. Strengthening these lax labeling requirements could prevent direct caffeine-induced harm, protect those most vulnerable to caffeine-related side effects, and enhance consumer autonomy and effective caffeine use...

Recent results obtained in our laboratory indicate that paraxanthine, the main metabolite of caffeine in humans, produces a significantly stronger locomotor activation in rats than caffeine. Furthermore, paraxanthine also produced a very significant increase in striatal extracellular concentrations of dopamine. Searching for an additional mechanism other than adenosine antagonism responsible for these psychostimulant-like effects, it was found that paraxanthine, but not caffeine, inhibited cGMP-preferring phosphodiesterases...

AIMS: Caffeine withdrawal was included in the research appendix of the DSM-IV to encourage additional research to assist with determining its status for the next version of the manual. Caffeine dependence was not included because of a lack of empirical research at the time of publication. This study assessed the beliefs of addiction professionals about the clinical importance of caffeine withdrawal and dependence. METHODS: A 6-item survey was developed and delivered electronically to the members of six professional organizations that focus on addiction...

BACKGROUND: College students who consume caffeinated alcoholic beverages (CaffAlc) are at increased injury risk. This study examines the extent to which a sensation-seeking personality accounts for the relationship between consumption of CaffAlc and negative outcomes. METHODS: A Web-based survey was administered to stratified random samples of 4907 college students from eight North Carolina universities in Fall 2009. Sensation seeking was assessed using the Brief Sensation-Seeking Scale (BSSS) (α=0...

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BACKGROUND: There has been some speculation that caffeine consumption may affect breast cancer. Most case-control studies have not documented evidence of a caffeine-breast cancer incidence link; however, there has been very little analysis of the possible effects of caffeine consumption on breast cancer survival. METHODS: We examined overall a 20-year survival of 96 women treated for breast cancer between 1990 and 1994. As part of their health history, these women were asked about coffee drinking...

The impact of caffeine on the behavioral effects of ethanol, including ethanol consumption and abuse, has become a topic of great interest due to the rise in popularity of the so-called energy drinks. Energy drinks high in caffeine are frequently taken in combination with ethanol under the popular belief that caffeine can offset some of the intoxicating effects of ethanol. However, scientific research has not universally supported the idea that caffeine can reduce the effects of ethanol in humans or in rodents, and the mechanisms mediating the caffeine-ethanol interactions are not well understood...

BACKGROUND: Caffeine reduces the amount of analgesic medications necessary to provide postoperative pain (POP) relief and augments treatments for headaches and dental pain. Despite considerable evidence of its beneficial effects, little is understood about the role of dietary caffeine consumption on baseline pain sensitivity or POP following oral surgery. METHOD: Baseline experimental pain testing (quantitative sensory testing [QST]) using four stimulus modalities was conducted on 30 healthy adults (53% females) before surgical extraction of four third molars...

Cigarette smokers have an increased risk for coronary artery disease. Nicotine present in cigarettes can adversely affect the cardiovascular system via stimulation of both sympathetic and parasympathetic neurons. Caffeine, another cardiovascular and central nervous system (CNS) stimulant, is commonly found in Ephedra and Ephedra-free dietary supplements. These caffeine-containing supplements also have been linked to cardiovascular toxicities. Although no longer on the U.S market, Ephedra-containing supplements are another source of cardiovascular and CNS stimulants, namely the ephedrine alkaloids...