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Medical Sciences	75%

Selected Abstracts

Caffeine, cognitive failures and health in a non-working community sample

HUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 1 2009
Andrew P Smith
Abstract Rationale Most studies of the effects of caffeine on performance have been conducted in the laboratory and further information is required on the real-life effects of caffeine consumption on cognition. In addition, possible effects of caffeine consumption on a range of health outcomes should also be assessed in these studies to enable cost-benefit analyses to be conducted. Objectives Secondary analyses of a large epidemiological database (N,=,3223 non-working participants, 57% female, with a mean age of 49.6 years, range 17,92 years) were conducted to examine associations between caffeine consumption (mean caffeine consumption was 140,mg/day, range 0,1800,mg) and cognitive failures (errors of memory, attention and action) in a non-working sample. Associations between caffeine consumption and physical and mental health problems were also examined. Methods The study involved secondary analyses of a database formed by combining the Bristol Stress and Health at Work and Cardiff Health and Safety at Work studies. Associations between caffeine consumption and frequency of cognitive failures and health outcomes were examined in a sample of non-workers. Results After controlling for possible confounding factors significant associations between caffeine consumption and fewer cognitive failures were observed. Initial analyses suggested that many health variables were associated with regular level of caffeine consumption. However, most of the significant effects of caffeine disappeared when demographic and lifestyle factors were controlled for. Consumption of caffeine was, however, associated with a reduced risk of depression. These effects were also observed in separate analyses examining the source of the caffeine (coffee and tea). Conclusions Overall, the results show that caffeine consumption may benefit cognitive functioning in a non-working population. This confirms earlier findings from working samples. This beneficial effect of caffeine was not associated with negative health consequences. Indeed, consumption of caffeine was found to be associated with a reduced risk of depression. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Caffeine levels in saliva: associations with psychosocial factors and behavioural effects

HUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 7 2001
Carolyn Brice
Abstract The present study had two main aims. The first was to examine associations between psychosocial factors, health-related behaviours, regular level of caffeine consumption, time of day and levels of caffeine in saliva following acute caffeine challenges. The second aim was to determine whether individual differences in changes in performance following ingestion of caffeine were related to levels of caffeine in saliva. One hundred and forty-four young adults participated in the study. Questionnaires were administered prior to the study to measure psychosocial characteristics, health-related behaviours and habitual levels of caffeine consumption. Two double-blind acute caffeine challenges were then carried out 1 week apart. Volunteers were given either placebo or 1.5 or 3,mg/kg of caffeine on each occasion. The challenges were carried out at 8,:,00, 11,:,00, 14,:,00 or 18,:,00,h so that the impact of time of day could be assessed. In the week between the two challenges the volunteers consumed either caffeinated or decaffeinated products. This allowed investigation of the effects of caffeine withdrawal on caffeine metabolism. Prior to each caffeine challenge volunteers performed a range of tasks, and a baseline saliva sample was taken. The tasks were repeated 1,h after ingestion of the caffeine, with saliva samples being taken at the start and end of the 1,h test battery. The results showed that the level of caffeine in the saliva was a good indicator of the dose of caffeine consumed and of compliance with the withdrawal manipulation. Caffeine levels were not influenced by time of day, habitual caffeine consumption, psychosocial factors or health-related behaviours. Individual differences in caffeine levels in saliva were not related to the individual variation in the effects of caffeine on performance. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Validation of core medical knowledge by postgraduates and specialists

MEDICAL EDUCATION, Issue 9 2005
Franciska Koens
Background, Curriculum constructors and teachers must decide on the content and level of objectives and materials included in the medical curriculum. At University Medical Centre Utrecht it was decided to test relatively detailed knowledge at a regular level in study blocks and to design a progress test aimed at the medical core knowledge that every graduating doctor should possess. This study was conducted to validate the level of knowledge tested in this progress test. Aim, We designed a questionnaire to investigate whether postgraduate trainees and experienced specialists agree with item writers on what is required core knowledge. Methods, Postgraduates and specialists received a questionnaire with 80 items designed to test core knowledge. Respondents were asked to indicate to what extent the items actually represented the core knowledge required of a recently graduated medical student. Results, Of the clinical questions, 82.4% were judged to reflect core knowledge, whereas only 42.4% of the basic science questions were judged to reflect core knowledge. There was a strikingly high correlation on the mean judgements per item of postgraduate trainees versus medical specialists (r = 0.975). Conclusion, Many items, written to reflect core knowledge, appear to be judged by postgraduates and clinicians as pertaining to non-core knowledge. Postgraduate trainees appear to be as capable as experienced specialists of making judgements regarding core knowledge. Fewer basic science items are regarded as core knowledge than clinical items. This may suggest that, specifically, basic science teachers do not agree with physicians on what is to be considered medical core knowledge for graduating doctors. [source]

Options and earnings announcements: an empirical study of volatility, trading volume, open interest and liquidity

EUROPEAN FINANCIAL MANAGEMENT, Issue 2 2000
Monique, W.M. Donders
In this paper we study the impact of earnings announcements on implied volatility, trading volume, open interest and spreads in the stock options market. We find that implied volatility increases before announcement days and drops afterwards. Also option trading volume is higher around announcement days. During the days before the announcement open interest tends to increase, while it returns to regular levels afterwards. Changes in the quoted spread largely respond to higher trading volume and changes in implied volatility. The effective spread increases on the event day and on the first two days following the earnings announcement. [source]