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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

This study addresses, among other things, the debate as to whether cognitive deficits do occur with a diagnosis of Chronic Fatigue Syndrome (CFS). Previous studies have indicated a potential mismatch between subjective patient ratings of impairment and clinical assessment. In an attempt to tackle some of the methodological problems faced by previous research in this field, this study recruited a large sample of CFS patients where adequate diagnosis had been made and administered an extensive battery of measures. In doing so this study was able to replicate previous published evidence of clear cognitive impairment in this group and demonstrate also that these deficits occurred independent of psychopathology. The conclusion drawn is that cognitive impairments can be identified if appropriate measures are used. Furthermore, the authors have shown that performance changes in these measures have been used to assess both efficacy of a treatment regime and rates of recovery.

The present paper will present some of the main conclusions from our recent programme on seafarers’ fatigue. Different sectors of the industry experience fatigue for different reasons. The crew of fishing vessels often report excessive fatigue due to long working hours and the physical conditions associa ted with the job. A second cause of fatigue is the rapid port turnarounds that have to be made by ships transporting dry cargo between ports in Europe. Similar problems occur in other transport sectors and another of our surveys showed that drivers who made the most deliveries reported the greatest fatigue in the road haulage sector. Other causes of fatigue may also occur (e.g. travelling to the ship). Recommendations are given about possible ways to prevent and manage fatigue. Given the variety of causes and consequences of fatigue, it is unlikely that a “one size fits all” approach will be successful and it will be necessary to address fatigue using several different approaches.

The aim of the present research was to investigate whether susceptibility to experimentally-induced respiratory virus infections and illness is related to measures of personality, physiological state, performance efficiency, and subjective ratings of alertness and motivation obtained prior to virus challenge. Two studies, using different viruses, showed that volunteers who subsequently developed colds had higher temperatures prior to virus challenge than those who remained free from illness. Similarly, those who later had colds were worse than other volunteers on certain performance tests given in the pre-challenge period. The results also showed that task-related motivation was related to subsequent infection. Personality scores were poor predictors of infection and illness, the only exception being introversion, which, in one study, was related to the likelihood of developing a sub-clinical infection.

Previous research has shown that caffeine increases alertness and improves sustained attention. In contrast to this, consumption of lunch leads to a decline in the ability to maintain attention. The main aim of the present study was to determine whether caffeine removes or reduces the postlunch drop in performance, an issue which is of considerable practical importance and theoretical interest. The results showed that caffeine improved performance on the Bakan vigilance task and removed the post-lunch dip observed in the decaffeinated condition. Similar effects were observed in one of the conditions of a mental rotation task. The lunch X caffeine interaction observed in the Bakan task did not change over the course of the task. In contrast to the performance data, lunch X caffeine interactions were not observed in analyses of cardiovascular function or subjective mood.

Summary Two studies involving double‐blind group comparative trials in human volunteers compared the effects of intranasal nedocromil sodium (2·6 mg active drug per nostril, q.i.d.) with placebo on clinical symptoms and performance impairment associated with the common cold. In the first study volunteers were challenged with rhinoviruses (RV9 and RV14), and in the second study with respiratory coronavirus. In both studies, active and placebo groups of volunteers were demographically similar. Infection rates in both groups were also similar. There were no withdrawals resulting from unusual symptoms related to either treatment. In the rhinovirus study (19, placebo; 20, nedocromil sodium) daily symptom scores and daily mean nasal secretion weights were significantly lower in the nedocromil sodium‐treated group. In the coronavirus study (26, placebo; 27, nedocromil sodium) there was little difference in the severity of colds between the active and placebo‐treated groups, but trends favoured nedocromil sodium. In both studies the impairment of performance in volunteers who developed a cold was significantly less in those treated with nedocromil sodium than in those treated with placebo.

We read with interest the letter from Patton et al on “Substance use among patients attending an accident and emergency department”.1 We have cross-sectional survey data from 2488 patients who attended one of eight accident and emergency departments in Wales. Individuals aged 18–40 years were sent a questionnaire after attending, following an injury at work, a …

Rationale The effects of caffeine on mood and performance are well established. Some authors suggest that caffeine merely reverses effects of caffeine withdrawal rather than having direct behavioural effects. It has also been suggested that withdrawal may be removed by a first dose of caffeine and further doses have little subsequent effect. These issues are examined here. Objectives The present study aimed to determine whether caffeine withdrawal influenced mood and performance by comparing regular consumers who had been withdrawn from caffeine overnight with non-consumers. Following this repeated caffeine doses were administered to test the claim that repeated dosing has no extra effect on mood or performance. Secondary analyses of data collected after a day of normal caffeine consumption were also carried out to examine some alternative explanations of their results which showed effects of caffeine after a day of normal caffeine consumption. Methods One hundred and twenty volunteers participated in the study. Regular caffeine consumption was assessed by questionnaire and this showed that 36 of the volunteers did not regularly consume caffeinated beverages. Volunteers were instructed to abstain from caffeine overnight and then completed a baseline session measuring mood and a range of cognitive functions at 08.00 the next day. Following this volunteers were given 0, or 1 mg/kg caffeine in a milkshake, glucose solution or water (at 09:00), followed by a second 0 or 1 mg/kg caffeine dose (at 09:40) and the test battery repeated at 10:00. Results The baseline data showed no effect of overnight caffeine withdrawal on mood or performance. In contrast, caffeine challenge improved vigilance performance and prevented decreases in alertness induced by completion of the task battery. The magnitude of these effects increased as a function of the number of doses of caffeine given. Secondary analyses of data from Christopher et al. (2003) also confirmed that effects of caffeine did not depend on length of withdrawal. Conclusions The present findings show no effect of overnight caffeine withdrawal on mood and performance. Caffeine challenge did have the predicted effect on alertness and vigilance, with the size of the effects increasing with caffeine dose. These findings suggest that the effects of caffeine are not due to reversal of effects of withdrawal, a view confirmed by secondary analyses of data collected after a day of normal caffeine consumption.

Stress influences susceptibility to the common cold. This has been demonstrated in studies that have controlled exposure to the virus and other confounding factors. Chronic stress is required to demonstrate these effects, and work stress and interpersonal stress pose the greatest risk. Many possible mechanisms have been advanced to account for the association between stress and colds. Stress-induced susceptibility to colds may reflect specific changes to the upper respiratory tract rather than more central mechanisms.

A multitude of instruments exist to assess dietary intake. Many, however, are time-consuming to administer, focus primarily on macronutrient composition or the effects of specific micronutrients, and do not consider the effects of foods and drinks that fail to add significant nutritional contributions (e.g. energy drinks, chewing gum). In order to address these issues the current paper introduces the Diet and Behaviour Scale (DABS). This 29-item questionnaire is used to measure both the frequency and amount of consumption of common foods and drinks, with a particular onus on functional foods and dietary variables of current concern. The DABS was administered to a large cohort of secondary school children from the South West of England at two time-points. At Time 1 (December, 2012) the cohort consisted of 3071 pupils, 2030 of whom responded to the questionnaire; at Time 2 (June, 2013) 3323 pupils made up the cohort, and 2307 completed the questionnaire. Factor analysis yielded a four-factor solution labelled Junk Food, Caffeinated Soft Drinks/Gum, Healthy Foods, and Hot Caffeinated Beverages. When investigating how these factors were related to demographic and lifestyle variables, Chi-square analyses uncovered the following relationships: being male was associated with high Junk Food intake; sleeping for fewer hours than average, achieving low school attendance, and having poor general health were associated with high intake of Caffeinated Soft Drinks/Gum; lower school year, more sleep, more frequent exercise, and good general health were associated with high intake of Healthy Foods; and being male, having a special educational needs status, reporting fewer hours of sleep, and being in an older school year were associated with a high intake of Hot Caffeinated Beverages. Whilst controlling for demographic and lifestyle variables, logistic regression analyses determined that poor general health was predicted by high consumption of Caffeinated Soft Drinks/Gum and low consumption of Healthy Foods. Though additional studies are required to further test the questionnaire and its associated factor structure, the DABS is considered to be a useful self-report measure of certain aspects of dietary intake, and is proposed as a useful tool for future research investigating dietary influences on psychological variables such as mental wellbeing.

Two hundred and seventy-five patients fulfilling the Centre for Disease Control (CDC) criteria for Chronic Fatigue Syndrome (CFS) completed measures assessing illness history, global ratings of well being, sleep, activity and psychopathology at baseline, 6 months, 18 months and 3 year follow-up. Forty-nine of these patients had been prescribed antidepressant medication, namely Tricyclic drugs or Selective Serotonin Re-uptake Inhibitors (SSRI). Data from the current study suggests that patients in the antidepressant medication group recover at a faster rate over time when compared to the untreated patient sample. In addition, the positive effects of antidepressant therapy are maintained at the 3-year follow-up point. It appears from these data that the SSRI in particular are responsible for improvements in the condition. Most importantly, these improvements include a reduction in the levels of fatigue recorded by patients. These findings have not been demonstrated in previous studies of the effect of antidepressant therapy for patients with this illness and this may reflect the short time periods studied in the earlier research.

BACKGROUND: Work-related fatigue is associated with sickness absence and mental and physical health problems, and may increase the risk of accidents and injuries at work. Relatively little is known about fatigue among seafarers, particularly during a tour of duty. The aim of this study was to describe the pattern of day to day fatigue among seafarers during a tour at sea. METHODS: Participants from the offshore support, short sea and coastal, and deep sea sectors of the UK shipping industry completed daily diaries. Information about sleep and fatigue was collected each day on waking and retiring. RESULTS: Fatigue on waking was a more sensitive measure of cumulative occupational fatigue than fatigue on retiring. Fatigue on waking increased between the start and end of tour. This increase took place in particular during the first week at sea, and was most apparent among those on shorter tours of duty. CONCLUSIONS: Day to day changes in fatigue are measurable, and may vary among particular sub-groups of seafarers. Used among larger groups, such a diary method could help identify times and activities associated with the greatest risk. Language: en

Background Previous research has suggested higher work stress among minority ethnic workers. Aims To determine levels of work stress in three ethnic groups, consider the contribution of racial discrimination to the groups' profiles of occupational and demographic associations with stress, and assess the association between work stress and well-being. Methods A household quota sample design was used, and 204 black African–Caribbean, 206 Bangladeshi and 216 white (UK born) working people took part in structured interviews. Results More black African–Caribbean respondents reported high work stress than either Bangladeshi or white respondents. Reported racial discrimination among black African–Caribbean female respondents was strongly associated with perceived work stress. Among the black African–Caribbean respondents, women who reported experiencing racial discrimination at work had higher levels of psychological distress. Conclusions Perceived work stress may be underpinned by exposure to racial discrimination at work among black African–Caribbean women, and this may affect their psychological well-being.

Rationale: A number of recent studies have suggested that caffeine only improves mood and cognitive performance in regular caffeine consumers who are caffeine withdrawn at test (the withdrawal hypothesis). This can be tested by investigating the effects of caffeine in non-consumers of caffeine. Objectives: To compare the effects of 2 mg/kg caffeine on mood and cognitive performance in overnight-withdrawn consumers and non-consumers of caffeine. Methods: Twenty-five overnight-withdrawn consumers and twenty-five non-consumers of caffeine were tested in a within-subjects design where they were given a drink containing 2 mg/kg caffeine on one test day and placebo on another test day. The order of conditions (caffeine/placebo) was counterbalanced. Mood and performance measures were taken before and after each drink, and pre-drink measures were used as covariates in the analysis of post-drink measures. Results: Analysis of baseline scores revealed no significant effects of caffeine withdrawal. Caffeine generally improved mood and cognitive performance, relative to placebo, in both subjects groups. These effects did not differ significantly between groups apart from three measures (fewer lapses of attention and ratings of alertness and anxiety) where the effects of caffeine were larger in the non-consumers. Conclusions: The present study revealed no negative effects of caffeine withdrawal. Beneficial effects of caffeine were observed in both withdrawn consumers and in non-consumers. Therefore, the withdrawal hypothesis is not an adequate explanation for the effects of caffeine.

Rationale The effects of caffeine on mood and performance are well established. One explanation of these effects is that caffeine removes negative effects induced by prior caffeine withdrawal. This was tested here by comparing effects of caffeine in withdrawn consumers and non-consumers (who by definition were not withdrawn). Objectives The present study aimed to determine whether caffeine withdrawal influenced mood and performance by comparing regular consumers who had been withdrawn from caffeine overnight with non-consumers. Following this the effects of acute caffeine challenges were compared in withdrawn consumers and non-consumers. In addition, comparisons were made between those with higher and lower caffeine consumption. Methods One hundred seventy-six volunteers participated in the study. Regular caffeine consumption was assessed by questionnaire and this showed that 56 of the sample did not regularly consume caffeinated beverages. Volunteers were instructed to abstain from caffeine overnight and then completed a baseline session measuring mood and a range of cognitive functions at 08.00 the next day. Following this approximately half of the volunteers were given 1 mg/kg caffeine in a milkshake or water (in the ‘no caffeine’ condition they were given just the milkshake or water) and the test battery repeated one hour later. A second test battery was carried out at 12.00 and a second caffeine challenge at 13.00. A final test session was carried out at 15.00. Results The baseline data revealed little evidence of effects of caffeine withdrawal on performance and mood. In contrast to this, caffeine produced a number of significant improvements in performance. There were some differences in the effects of caffeine on regular and non-consumers, with caffeine tending to reduce reaction time in regular consumers while the opposite was true for non-consumers. Conclusions The present results show little evidence of effects of caffeine withdrawal on performance. In contrast, caffeine challenge produced improvements in aspects of performance and these were often not modified by regular caffeine consumption patterns. The differences in effects of caffeine that were observed between non-consumers and regular consumers were in functions that were unaffected by caffeine withdrawal. These findings show that the observed beneficial effects of caffeine cannot be interpreted in terms of a reversal of caffeine withdrawal.

Background The current study was conducted as part of a research project into the evaluation and assessment of healthcare provision and education in Chronic Fatigue Syndrome (CFS). One aim of the study was the development of informative and educational literature for both General Practitioners (GP) and sufferers. Issues such as diagnosis, management and treatment of the syndrome should be included in information booklets written by healthcare professionals. It was important to begin the process by assessing the level of specialist knowledge that existed in typical GP surgeries. This data would then be compared to data from CFS patients. Method 197 survey booklets were sent to CFS sufferers from an existing research panel. The patients approached for the purpose of the study had been recruited onto the panel following diagnosis of their illness at a specialised CFS outpatient clinic in South Wales. A further 120 booklets were sent to GP surgeries in the Gwent Health Authority region in Wales. Results Results from the study indicate that the level of specialist knowledge of CFS in primary care remains low. Only half the GP respondents believed that the condition actually exists. Conclusion Steps are recommended to increase the knowledge base by compiling helpful and informative material for GPs and patient groups.

There are well documented acute and chronic effects of cannabis use. However, less is known about any effects on safety within the context of work and everyday life. The aim of the study was to examine any association between cannabis use and injuries and accidents. A postal questionnaire survey was conducted among people selected at random from the electoral registers of Cardiff and Merthyr Tydfil. Cannabis use was associated with both minor injuries and accidents, particularly among those with high levels of other associated risk factors. Cannabis use was associated with a significant detrimental impact on safety. It is possible that this is linked to an amplification of other risk factors associated with accidents and injuries. This has potentially wide reaching implications particularly in the context of other work and lifestyle characteristics.

There are well documented acute and chronic effects of cannabis use on mental functioning. However, less is known about any effects on cognition within the context of work and everyday life. The aim of the study was to examine any association between cannabis use and cognitive performance, mood and human error at work. Cannabis users and controls completed a battery of laboratory based computer tasks measuring mood and cognitive function pre- and post-work at the start and end of a working week. They also completed daily diaries reporting their work performance. Cannabis use was associated with impairment in both cognitive function and mood, though cannabis users reported no more workplace errors than controls. Cannabis use was associated with lower alertness and slower response organization. In addition, users experienced working memory problems at the start, and psychomotor slowing and poorer episodic recall at the end of the working week. This pattern of results suggests two possible effects. First a ‘hangover’-type effect which may increase with frequency of use. Second a subtle effect on cognitive function, perhaps more apparent under cognitive load and/or fatigue, which may increase with more prolonged use. The results also highlight the importance of the timing of testing within the context and routine of everyday life.

A study of 376 young British adults showed that estimated daily caffeine consumption increased with age, and was associated with smoking and greater alcohol consumption. Non-consumers of caffeine avoided tea and coffee (even the de-caffeinated form). Level of caffeine consumption was not associated with impulsivity, sociability, extraversion or trait anxiety.

BACKGROUND: Psychotropic medication has the potential to impair psychomotor and cognitive function, and several medications have well documented links to increased accident and injury susceptibility. Those developed more recently have many fewer side effects. However, there is little work examining any association between psychotropic medication use and safety within the context of other demographic, health and lifestyle factors. AIMS: To examine and compare any associations between psychotropic medication use (including benzodiazepines, tricyclics and SSRIs) and accidents, injuries and cognitive failures in a community sample. METHODS: A postal questionnaire survey was conducted among people selected at random from the electoral registers of Cardiff and Merthyr Tydfil. RESULTS: Psychotropic medication use was associated with accidents, injuries and cognitive failures, particularly among those who already had higher levels of other risk factors and/or continuing mental health problems. CONCLUSIONS: The well established associations between accidents and injuries and older psychotropic medications were replicated. SSRIs, however, were relatively safer. The study also highlighted the need to consider any effect of psychotropic medication within the context of both mental health status and other factors.

Rationale There is a large literature on the effects of caffeine on performance. Most of the studies have been conducted in the laboratory and further information is required on the effects of caffeine consumption on performance and safety at work. Objectives The present studies aimed to determine whether the level of caffeine consumption influenced changes in alertness and performance over the working day. Secondary analyses of a large epidemiological database were also conducted to examine associations between caffeine consumption and cognitive failures and accidents at work. Methods In the first study 110 volunteers, all of whom were regular caffeine consumers, rated their alertness and carried out a simple reaction time task before and after work on a Monday and Friday. Caffeine consumption during the day was recorded and volunteers were sub-divided into low and high consumers on the basis of a median split (220 mg/day). The second 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. In the first analyses associations between caffeine consumption and frequency of cognitive failures were examined in a sample of 1253 white-collar workers. The second set of analyses examined associations between caffeine consumption and accidents at work in a sample of 1555 workers who were especially at risk of having an accident. Results The results from the first study showed that those who consumed higher levels of caffeine reported significantly greater increases in alertness over the working day and a significantly smaller slowing of reaction time. The results from the second study demonstrated significant associations between caffeine consumption and fewer cognitive failures and accidents at work. After controlling for possible confounding factors it was found that higher caffeine consumption was associated with about half the risk of frequent/very frequent cognitive failures and a similar reduction in risk for accidents at work. Conclusions Overall, the results from the three analyses show that caffeine consumption may have benefits for performance and safety at work.

The aim of this paper is to discuss issues that fall within the general concept of well-being, with special emphasis on approaches that have been used in studies of nutrition and behaviour. Following this, two specific studies are described in detail, the first examining high-fibre breakfast cereals and the second investigating effects of inulin. Studies of nutrition and well-being can be categorised in a number of ways. One method involves examining acute effects of nutrition on mood and cognitive functioning. Another method has been to examine cross-sectional associations between dietary habits and questionnaire measures of reported health. Examples are given showing that regular consumption of a high-fibre diet is associated with better-reported physical and mental health. The problem with such correlational studies is that it is impossible to infer causality. Intervention studies are necessary to achieve this and some examples of this approach are given. In the first study reported here, we examined whether consumption of high-fibre breakfast cereal led to an increase in energy. Such an effect was observed and plausible biological mechanisms underlying such results are described. A similar methodology has recently been used to examine the effects of inulin. In this case the results showed no negative side-effects of taking inulin but there were no beneficial effects of inulin on measures of well-being (both subjective reports and objective measures). Possible reasons for these effects are discussed.

Background There is a dearth of information examining minor injuries and cognitive failures in the workplace. Aims This study aims to describe the incidence of, and characteristics associated with, minor injuries, cognitive failures and accidents in the workplace. Methods The study was a community based postal questionnaire survey of people selected at random from the Electoral Registers of Cardiff and Merthyr Tydfil; 7980 questionnaires were returned. Results Frequent/very frequent minor injuries were reported by 9.8% of the workers and frequent/very frequent cognitive failures (e.g. problems of memory, attention or action) by 10.5%. Work accidents requiring treatment were reported by 5.6% of the workers. Minor injuries, cognitive failures and accidents were associated with a number of demographic and health factors. In addition, minor injuries, cognitive failures and accidents were found to be related to each other. Conclusions A large number of workers experience accidents and minor injuries at work. Minor injuries are not recorded by official sources but could have implications in productivity and worker health. Factors identified in this study, as associated with injuries or accidents, could be addressed by specific workplace policies or by raising individual awareness of the risks.

An experiment was carried out to examine the effects of sugar and aspartame in coffee on aspects of memory. The results showed that subjects given a sweetener performed a logical reasoning task more accurately but more slowly than subjects with no sweetener. Performance of free recall, delayed recognition memory, and semantic memory tasks was unaffected by the sweetener.

Background It has been suggested that infection with Toxoplasma gondii is associated with slow reaction and poor concentration, whilst infection with Coxiella burnetii may lead to persistent symptoms of fatigue. Methods 425 farmers completed the Revised Clinical Interview Schedule (CIS-R) by computer between March and July 1999 to assess psychiatric morbidity. Samples of venous blood had been previously collected and seroprevalence of T. gondii and C. burnetii was assessed. Results 45% of the cohort were seropositive for T. gondii and 31% were positive for C. burnetii. Infection with either agent was not associated with symptoms reflecting clinically relevant levels of concentration difficulties, fatigue, depression, depressive ideas or overall psychiatric morbidity. Conclusions We do not provide any evidence that infection with Toxoplasma gondii or Coxiella burnetii is associated with neuropsychiatric morbidity, in particular with symptoms of poor concentration or fatigue. However, this is a relatively healthy cohort with few individuals reporting neuropsychiatric morbidity and therefore the statistical power to test the study hypotheses is limited.

Emotional information is better remembered when mood at the time of retrieval matches it in valence (positive mood, positive material). An associative memory model predicts that this 'mood congruent' facilitation is due to the mood-related reactivation at retrieval of emotional responses which were linked to valenced information at encoding. To test this model, we presented subjects with positive and negative words at study and manipulated their mood at test while using functional imaging to monitor brain activity. Subjective mood ratings and heart rate variability both indicated that the manipulation was effective, and memory performance showed a strong trend towards facilitation in congruent conditions. In the functional imaging data, valence-specific conjunctions between encoding activity predicting subsequent memory in a congruent mood and retrieval activity relating to mood congruent recollection revealed shared responses in subgenual cingulate for positive valence and posteriolateral orbitofrontal cortex for negative valence, thus supporting the associative model. To elucidate the mnemonic basis of facilitation, independent of valence, we examined the shared correlates of positive and negative congruence and found that parts of the episodic memory system were activated by congruence in correct rejection trials, but no part of this system was activated by congruence in correctly remembered trials. This pattern suggests that mood congruent facilitation occurs at the level of attempted recall rather than that of successful recollection.

This study aimed to examine demographic, lifestyle, mental health and personality factors associated with illicit recreational drug use, heavy alcohol consumption and smoking in a community-based population sample. A postal questionnaire survey was conducted of people who were selected at random from the Electoral registers of Cardiff and Merthyr Tydfil. Illicit drug use was associated with risk taking, neuroticism, being male, having a higher education qualification, not being married, being unemployed, being aged under 25 years, smoking, heavy alcohol consumption and living in Cardiff. Smoking was associated with anxiety, depression, being female, lower income and educational qualifications, looking after the family or home, being aged over 25 years, illicit drug use and heavy alcohol use. Heavy alcohol consumption was associated with not being depressed, experiencing sleeping problems, risk taking, being male, higher income, no higher educational qualification, not being married, being a student, being aged under 25 years, smoking and illicit drug use. Illicit drug use, smoking and heavy alcohol use were strongly associated with each other. Illicit drug use was associated with alcohol use and, to an even greater extent, with smoking. Illicit drug and alcohol use were associated with similar characteristics, but smoking was associated with a rather different demographic combination.

The aim of the present study was to assess the impact of upper respiratory tract illnesses on efficiency at work. This was done using the ‘after-effect’ technique with measurements being taken before and after work and the difference between these giving an indication of efficiency over the day. All of the volunteers (N = 48) were tested when healthy to provide baseline data for simple reaction time and mood. When volunteers developed an upper respiratory tract illness (URTI) they (N = 16) repeated the procedure. Those who remained healthy over a three month period (N = 32) were recalled as healthy controls. In addition to the performance test and mood ratings the volunteers kept a sleep log and also rated how demanding the day had been and how much effort they had put in. The results showed that those with URTIs had slower reaction times and a more negative mood both before and after work. Illness did not have an effect on ratings of demand and effort. Those who were ill reported greater sleep disturbance but this could not account for the impaired performance or negative mood states. These results suggest that upper respiratory illnesses may impair performance and well-being at work.

There have been numerous studies on the effects of caffeine on behaviour and cardiovascular function. It is now important to clarify the mechanisms that underlie such effects, and the main objective of the present study was to investigate whether changes in central noradrenaline underlie some of the behavioural and cardiovascular effects of caffeine. This was examined using a clonidine challenge paradigm. Twenty-four healthy volunteers were assigned to one of four conditions: (i) clonidine/caffeine; (ii) clonidine/placebo; (iii) placebo/caffeine; (iv) placebo/placebo. Baseline measurements of mood, cognitive performance, saccadic eye movements and cardiovascular function were recorded. Subsequently, volunteers were given either clonidine (200 μg) or placebo and consumed coffee containing caffeine (1.5 mg/kg) or placebo. The test battery was then repeated 30 min, 150 min and 270 min later. A second cup of coffee (with the same amount of caffeine as the first) was consumed 120 min after the first cup. The results showed that clonidine reduced alertness, impaired many aspects of performance and slowed saccadic eye movements; caffeine removed many of these impairments. Both clonidine and caffeine influenced blood pressure (clonidine reduced it, caffeine raised it) but the effects appeared to be independent, suggesting that separate mechanisms were involved. In addition, there were some behavioural effects of caffeine that were independent of the clonidine effect (e.g. effects on speed of encoding of new information) and these may reflect other neurotransmitter systems (e.g cholinergic effects). Overall, the results suggest that caffeine counteracts reductions in the turnover of central noradrenaline. This mechanism may underlie the beneficial effects of caffeine seen in low alertness states.

Background Accidents and injuries at work account for several million working days lost each year. Cognitive failures (problems of memory, attention or action) can lead to accidents and injuries in certain contexts. Aim This work describes the prevalence and associations of workplace accidents, minor injuries and cognitive failures reported by respondents to a follow-up postal questionnaire as part of the community-based Bristol Stress and Health Study. Methods Postal questionnaires were sent to 4673 people who participated in the first phase of the study (in which questionnaires were sent to individuals selected at random from the electoral roll). Results Four per cent of workers reported an accident at work, 8% reported quite or very frequent minor injuries and 13% reported quite or very frequent cognitive failures. Accidents at work were associated with being male, smoking and higher negative job characteristics. Respondents reported workplace accidents at a level similar to the overall UK rate. Accidents and minor injuries, and minor injuries and cognitive failures, shared common associations and all three outcomes were associated with each other. Conclusion Information about cognitive failures is important in the study of accidents and injuries at work. In addition, negative job characteristics represent part of the context in which human error is translated into injury.

The aim of the present research was to extend previous research which has shown that consumption of breakfast is associated with reports of better health. Previous research has confirmed this in samples in the age ranges from mid-twenties to early eighties. The present study considered young adults (189 volunteers, aged between 19-21 years, mean age 19.6 years) living at home. The results showed that skipping breakfast is associated with reports of poorer health and that regular breakfast cereal consumption is associated with better reported health. The effects of breakfast could not be explained by other health-related behaviours or other aspects of diet. Further research is now required to determine the mechanisms underlying this robust association to examine whether it is observed with objective indicators of health and specific diseases.

The literature suggests that the following effects on behavior of adult humans may occur when individuals consume moderate amounts of caffeine. (1) Caffeine increases alertness and reduces fatigue. This may be especially important in low arousal situations (e.g. working at night). (2) Caffeine improves performance on vigilance tasks and simple tasks that require sustained response. Again, these effects are often clearest when alertness is reduced, although there is evidence that benefits may still occur when the person is unimpaired. (3) Effects on more complex tasks are difficult to assess and probably involve interactions between the caffeine and other variables which increase alertness (e.g. personality and time of day). (4) In contrast to the effects of caffeine consumption, withdrawal of caffeine has few effects on performance. There is often an increase in negative mood following withdrawal of caffeine, but such effects may largely reflect the expectancies of the volunteers and the failure to conduct “blind” studies. (5) Regular caffeine usage appears to be beneficial, with higher users having better mental functioning. (6) Most people are very good at controlling their caffeine consumption to maximise the above positive effects. For example, the pattern of consumption over the day shows that caffeine is often consumed to increase alertness. Indeed, many people do not consume much caffeine later in the day since it is important not to be alert when one goes to sleep. In contrast to effects found from normal caffeine intake, there are reports that have demonstrated negative effects when very large amounts are given or sensitive groups (e.g. patients with anxiety disorders) were studied. In this context caffeine has been shown to increase anxiety and impair sleep. There is also some evidence that fine motor control may be impaired as a function of the increase in anxiety. Overall, the global picture that emerges depends on whether one focuses on effects that are likely to be present when caffeine is consumed in moderation by the majority of the population or on the effects found in extreme conditions. The evidence clearly shows that levels of caffeine consumed by most people have largely positive effects on behavior. Excessive consumption can lead to problems, especially in sensitive individuals.

Toxoplasma gondiiis known to induce specific behavioural changes in its intermediate hosts. This is usually considered to be an evolutionary adaptation aimed to increase the probability of transmission of the parasite into its definitive host, the cat, by predation. In rodents an increase of reaction time as well as many other specific behavioural patterns have been observed. Here we report the results of our double blind study showing the significantly longer reaction times of 60 subjects with latent toxoplasmosis in comparison with those of 56 controls. Moreover, the existence of a positive correlation between length of infection and mean reaction time suggested that slow and cumulative effects of latent toxoplasmosis rather than a one-step (and possibly transient) effect of acute toxoplasmosis disease are responsible for the decrease of psychomotor performance of infected subjects. To our knowledge, this is the first study confirming the existence of such parasite-induced changes in human behaviour that could be considered in evolutionary history of the human species as adaptive from the point of view of parasite transmission.

The present paper will give a review of 10 years of our research on the effects of caffeine on cognition and mood. Research has demonstrated that caffeine has beneficial effects on performance of tasks requiring sustained attention and that these effects are readily observed in low alertness situations (after lunch; at night; when a person has a cold). Although many of the studies of caffeine have used very large single doses, recent studies have demonstrated that beneficial effects can be observed with more realistic doses and drinking regimes that equate to real-life intake. Furthermore, the improved performance can be demonstrated using simulations real-life tasks and in the context of a normal working day.

The objective of the present investigation was to study the relationship between breakfast consumption and subjective reports of mental health and health-related behaviours in a general population sample (126 subjects aged between 20 and 79 years). Individuals who consumed a cereal breakfast each day were less depressed, less emotionally distressed and had lower levels of perceived stress than those who did not eat breakfast each day. Those who consumed breakfast had a healthier lifestyle than the others in that they were less likely to be smokers, drank less alcohol and had a healthier diet. However, the relationship between cereal breakfast consumption and mental health did not reflect these differences in the smoking, alcohol consumption and diet. In conclusion, there is an association between breakfast consumption and well-being which cannot entirely be accounted for by differences in other aspects of diet or smoking and alcohol consumption. Further intervention studies are now needed to establish whether causal relationships and mechanisms underlie the associations seen in this study.

It has recently been claimed that the beneficial effects of caffeine on performance might represent deleterious effects of caffeine deprivation rather than an actual net benefit due to caffeine use. This view was tested here by examining the effects of two doses of caffeine (1.5 mg/kg and 3 mg/kg) and then the effects of caffeine withdrawal. The results showed that administration of caffeine improved performance, whereas there was no evidence of impairment when subjects were deprived of caffeine. It has been argued that subjects should be deprived of caffeine for about a week to remove negative 162effects of deprivation before studies of the acute effects of caffeine are carried out. This was done here, and beneficial effects of caffeine were still observed. These results support the view that caffeine consumption leads to beneficial effects on performance, whereas caffeine withdrawal produces no impairments.

The present study investigated the effects of snacks on simulated driving for 24 volunteers who carried out a driving task three times. On each occasion a presnack baseline of 1 hr. of driving was taken. The snack conditions were (a) no snack (b) a 65 g-filled chocolate bar, and (c) an equicaloric snack of cheese and biscuits. Following the snack the volunteers then carried out another hour of driving. Analysis showed that following consumption of the chocolate the volunteers drove more carefully and hit the side of the track less often.

Background Irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) are associated with several risk factors for developing cognitive impairment. These include altered cytokine levels, concurrent mood disorders, and the presence of chronic pain. This observational study aimed to explore the cognitive profile of patients with these conditions. Methods Participants completed the Cardiff Cognitive Battery, a series of computerized neuropsychological performance tests that examine a range of cognitive function including psychomotor speed, memory, and intelligence. A progressive analysis of covariance model was used with demographic details, anxiety and depression scores entered as covariates. Fecal calprotectin levels were measured in IBD patients to determine disease activity. Key Results In total 231 participants were recruited (150 IBD patients, 40 IBS patients, and 41 healthy controls). IBD patients had significantly lower scores on fluid (p = 0.01) and crystalline intelligence tests (p = 0.028) compared to healthy volunteers, however, this reflected differences in concurrent mood disorder and level of education. When these factors were added as covariates, there was no significant difference between the groups. Duration and activity of disease did not affect cognitive function in IBD patients. Severity of symptoms had no impact on cognition in patients with IBS. Conclusions & Inferences The results of this observational study do not support the hypothesis that IBS or IBD have an intrinsic disease process that is associated with cognitive dysfunction. It is possible that concurrent mood disorders, in particular depression, may affect the cognitive performance of patients with IBD in specific tasks.

This study examined the effects and aftereffects of naturally occurring upper respiratory tract illnesses on mood and performance. Twenty-six subjects (12 males, 14 females, mean age 23 years 10 months, age range 18–39 years) were tested once a week for a period of a month. Fifteen subjects were suffering from a common cold on the first week and the other 11 subjects were matched healthy controls. Subjects attended for an initial 3-h testing period that consisted of a set of practice trials and two test sessions involving mood rating and performance of a battery of tests measuring psychomotor functions, attention, and memory. Sessions 3, 4, and 5 took place 1, 2, and 3 weeks later, respectively. In addition to measuring mood and mental performance, symptom severity was rated on a subjective checklist. The results showed that subjects with a cold reported an increase in negative mood and that this was only significant in the first week. Impairments of psychomotor function (simple reaction time and tracking) were also observed at this time. Performance of sustained and selective attention tasks was also impaired in subjects with colds but this effect was only significant in the second week. Other functions such as working and semantic memory were unimpaired in subjects with colds at any point in the experiment. Overall, the present results confirm many of the earlier results obtained in studies of experimentally induced upper respiratory tract illnesses. Indeed, these results are both of great practical importance and theoretical interest and further studies must now elucidate the mechanisms underlying these effects.

The aim of the present study was to provide preliminary information on the acute and chronic effects of infectious mononucleosis (IM) on memory, attention, psychomotor performance and mood. These issues were examined by comparing individuals with acute IM, those who had the initial illness some months before, and matched healthy controls. Objective measures of memory, attention, motor skills and visual functions were obtained, as were subjective reports of mood. The results showed selective effects of acute IM on performance and mood, with the profile of impairments being very similar to those observed in previous studies of influenza. Different impairments were observed in subjects who had the primary illness several months before, and the effects observed in this group were similar to those observed in recent studies of chronic fatigue syndrome patients. Both acute and chronic IM subjects reported similar levels of symptoms and psychopathology, with both groups having greater scores than the controls. However, the performance impairments did not reflect symptoms or psychopathology. One may conclude that the study of IM will provide important data on both the acute and longer lasting effects of viral infections on the brain and behaviour.

There is increasing evidence that the central nervous system (CNS) and immune system interact with one another. Hormones released from the brain circulate through the bloodstream and alter the functional activity of immune cells and immune cells produce chemical messengers that alter brain function. During the last several years of operation of the Medical Research Council’s Common Cold Unit (CCU), we together with David Tyrrell and his staff embarked on a series of studies addressing the possible interrelations between the CNS and immune system. In particular, we studied how psychological states might influence pathogenesis of upper respiratory infections and how infections might influence the processing of information. In this chapter, we review the literature relevant to each of these projects and summarise the work done at the CCU.

Objective The aim of the present research was to investigate whether individuals with a common cold showed impaired ability on a simulated driving task and the ability to detect potential collisions between moving objects. Design The study involved comparison of a healthy group with a group with colds. These scores were adjusted for individual differences by collecting further data when both groups were healthy and using these scores as covariates. On both occasions, volunteers rated their symptoms and carried out a simulated driving session. On the first occasion, volunteers also carried out a collision detection task. Setting University of Leeds Institute for Transport Studies. Sample Twenty-five students from the University of Leeds. Ten volunteers were healthy on both occasions and 15 had a cold on the first session and were healthy on the second. Main outcome measures In the collision detection task, the main outcomes were correct detections and response to a secondary identification task. In the simulated driving task, the outcomes were speed, lateral control, gap acceptance, overtaking behaviour, car following, vigilance and traffic light violations. Results Those with a cold detected fewer collisions and had a higher divided attention error than those who were healthy. Many basic driving skills were unimpaired by the illness. However, those with a cold were slower at responding to unexpected events and spent a greater percentage of time driving at a headway of, Article summary Article focus The study investigated effects of the common cold on simulated driving and collision detection. It tested the hypotheses that people with a cold would show impairments in collision detection and aspects of simulated driving. Key messages Drivers with a common cold respond more slowly to unexpected events and drive too close to the car in front. Collision detection is impaired when a person has a cold. Strengths and limitations of this study The study used established methodologies to investigate the topic. This small scale study requires replication and extension to provide a more detailed profile of potential effects of the common cold on driving.

Previous studies of experimentally induced colds and influenza have shown that sleep is impaired during these illnesses. This has been observed for both subjective reports and polysomnographically recorded sleep. The present study investigated whether naturally occurring illnesses influenced sleep measured using actimetry. Twenty-two volunteers had their sleep recorded on two occasions approximately 14 days apart. On the first occasion 15 of the volunteers had a cold and the other 7 were healthy. On the second occasion all volunteers were healthy. No significant differences were found between the healthy and colds group for any of the actiwatch measures. However, the numerical trends suggested that those with colds had lower sleep efficiency. Significant correlations were found between nasal symptoms and sleep disturbance. Reported fatigue the next day was also associated with less efficient sleep. These results confirm that the common cold can have detrimental effects on sleep but suggest that the overall magnitude of the effect is small and that it may reflect nasal obstruction.

This study examined the effects of fat content and meal size on postlunch changes in mood, performance, and cardiovascular function. Forty-six subjects (20 males, 26 females) were tested before and after lunch. Subjects were assigned to one of the following lunch condition: a) low fat (23 g), large meal (860 g); b) low fat (18 g), small meal (600 g); c) high fat (84 g), large meal (840 g); d) high fat (79 g), small meal (530 g). The results showed only small effects of fat composition and meal size, with no cardiovascular effects being observed and no evidence of fat content or the weight of the meal influencing performance of logical reasoning or cognitive vigilance tasks. A few effects of meal type were significant in the mood data, but given the large number of analyses conducted, these could represent chance effects. Results from two selective attention tasks showed that subjects given the high-fat meals responded more slowly but more accurately, which differs from the effects of carbohydrate, protein, and calorie content reported in earlier papers. Weight of the meal influenced the degree of distraction from near and far distractors and also the accuracy of responses to central and peripheral targets. However, both the effects of fat and meal size were modified by task parameters, and further research is required before firm conclusions can be drawn about the functional importance of the influences of nutrient content and meal size on performance. The high-fat and large meals were rated as more acceptable than the low-fat and small meals. These differences in acceptability could not, however, account for the changes in performance observed after consumption of the different meal types.

Two experiments examined the effect of breakfast (1.89 MJ) and caffeine (4 mg/kg) on cognitive performance, mood and cardiovascular functioning. In the first experiment, breakfast had no effect on performance of sustained attention tasks, but it increased pulse rate and influenced mood. The mood effects after breakfast differed between a cooked breakfast and a cereal/toast breakfast. In contrast to the effects of breakfast, this relatively high dose of caffeine improved performance of the sustained attention tasks, increased blood pressure and increased mental alertness. In the second experiment, effects of a breakfast and caffeine on mood and cardiovascular functions confirmed the results of the first study. The breakfast improved performance on free recall and recognition memory tasks, had no effect on a semantic memory task and impaired the accuracy of performing a logical reasoning task. In contrast to this, caffeine improved performance on the semantic memory, logical reasoning, free recall and recognition memory tasks. Overall, these results show that breakfast can improve performance in some but not all cognitive tasks and that these changes are very different from those observed after lunch, and those produced by caffeine.

An experiment was carried out to examine the effects of an evening meal and caffeine (3 mg/kg) on performance, mood and cardiovascular functioning. Subjects given a meal reported that they felt stronger, more proficient and more interested than subjects in the no-meal condition. They also performed a logical reasoning task more quickly than the no-meal group. However, no effects were found on sustained attention tasks or tasks involving recall or recognition of word lists. The effects of evening meals are, therefore, different from either those observed after lunch or breakfast. Caffeine improved alertness and performance on sustained attention tasks for the group as a whole. Interactions between caffeine conditions and levels of impulsivity of the subjects were also found in memory tasks.

OBJECTIVES. This study was conducted to test the supposition that both smoking and consuming alcohol suppress host resistance to viral infections. METHODS. The relations between smoking, alcohol consumption, and the incidence of documented clinical colds were prospectively studied among 391 subjects intentionally exposed to one of five respiratory viruses and 26 subjects given saline. Clinical colds were defined as clinical symptoms verified by the isolation of virus or by an increase in virus-specific antibody titer. Analyses included control variables for demographics; body weight; virus; and environmental, immunological and psychological factors. RESULTS. Smokers were at greater risk for developing colds than nonsmokers because smokers were more likely both to develop infections and to develop illness following infection. Greater numbers of alcoholic drinks (up to three or four per day) were associated with decreased risk for developing colds because drinking was associated with decreased illness following infection. However, the benefits of drinking occurred only among nonsmokers. CONCLUSIONS. Susceptibility to colds was increased by smoking. Although alcohol consumption did not influence risk of clinical illness for smokers, moderate alcohol consumption was associated with decreased risk for nonsmokers.