The effects of experimentally induced respiratory virus infections on performance

Stress and Illness: A Role for Specific Emotions

Research on stress and disease has often afforded an important role to emotion, typically conceptualized in broad categories (e.g., negative emotions), viewed as playing a causal role (e.g., anger contributing to pathophysiology of cardiovascular disease), and measured using self-report inventories. In this article, I argue for the value of evaluating specific emotions, considering bidirectional causal influences, and assessing actual emotional responding when considering the role that emotions play in the stress-disease relationship. In terms of specificity, specific emotions (e.g., anger, sadness, and embarrassment) can be linked with particular health outcomes (e.g., cardiovascular disease and musculoskeletal disease). In terms of bidirectionality, the influences of emotions on disease as well as the influences of disease on emotional functioning can be considered. In terms of assessing actual emotional responding, emotions can be studied in vivo under controlled conditions that allow behavioral, physiological, and subjective responses to be measured during different kinds of emotional functioning (e.g., responding to emotional stimuli, interacting with relationship partners, and downregulating emotional responses). With these considerations in mind, I review early theories and empirical studies in psychosomatic medicine that considered the role of specific emotions and emotion-related behaviors. Studies from our laboratory are presented that illustrate a) differences in patterns of autonomic nervous system responding associated with specific emotions, b) relationships between specific emotions and particular health outcomes in the context of social relationships, c) age as a moderator of the relationship between specific emotions and well-being, d) bidirectional influences (emotions influencing disease and disease influencing emotional functioning), and e) impact of changes in emotional functioning in individuals with neurodegenerative diseases on the health of familial caregivers.

Brain Structures Implicated in Inflammation-Associated Depression

Systemic inflammation rapidly impairs mood, motivation, and cognition inducing a stereotyped cluster of symptoms collectively known as "sickness behaviors." When inflammation is severe or chronic, these behavioral changes can appear indistinguishable from major depressive disorder (MDD). Human and rodent neuroimaging combined with experimental inflammatory challenges has clarified the neural circuitry associated with many of the key features of inflammation-induced-sickness behavior, and in so doing revealed often-remarkable commonalities with circuit abnormalities observed in MDD. This review aims to provide the first synthesis of this work illustrating areas of convergence and divergence with the MDD literature as well as highlighting areas for future study.

Acute Tension-Type Headaches Are Associated with Impaired Cognitive Function and More Negative Mood

BACKGROUND/AIMS

Research has shown that migraine is often associated with memory problems. There have, however, been few studies of tension-type headache (TTH) and cognition. People who report frequent headaches often report high levels of negative affect. However, less is known about the acute effects of TTH on mood. To address these gaps in our knowledge, two studies examined the effects of acute TTH on -cognitive performance and mood.

METHODS

Both studies involved one group of participants completing a battery of tasks when they had a TTH and when they had no headache. Another group (the control) was headache free on both occasions. Duration of the headache was >30 min and <4 h. In the "no headache" condition, the participants were headache free for at least 24 h. In the first study, 12 participants (6 with TTH and 6 controls) completed a computerized battery measuring mood and aspects of cognition. In the second study, 22 participants (7 TTH, 5 after TTH, and 10 controls) completed paper and pencil mood and cognitive tasks.

RESULTS

In the first study, having a headache was associated with an increase in negative affect both before and after the tasks. Three performance tasks showed impairments when the participants had headaches: logical reasoning was slower and less accurate; retrieval from semantic memory was slower; and reaction times in the categorical search task were slower. Results from the second study confirmed the global increase in negative affect when the person has a TTH. The results confirmed the impairments in the logical reasoning and semantic processing tasks, and also showed that those with a TTH had greater psychomotor slowing and were more easily distracted. Effects did not continue after the headache had gone.

CONCLUSION

Two small-scale studies have shown that TTH is associated with negative affect and impaired cognitive function. It is now of interest to determine whether OTC treatment can remove these effects.

Twenty-five years of research on the behavioural malaise associated with influenza and the common cold

Minor illnesses such as the common cold and influenza are frequent and widespread. As well as specific symptoms such as nasal problems and fever, these illnesses are associated with a behavioural malaise. One feature of this malaise is reduced alertness and this has been confirmed using subjective reports and objective measures of performance. Such effects have been obtained with both experimentally induced infections and in studies of naturally occurring illnesses. The mechanisms underlying the effects are unclear but possibly reflect effects of cytokines on the CNS which result in changes in neurotransmitter functioning that lead to reduced alertness. The malaise induced by these illnesses has many real-life consequences and activities such as driving and safety at work may be at risk. These illnesses not only have direct effects on performance and mood but also make the person more sensitive to effects of other negative influences such as noise, alcohol and prolonged work. Countermeasures include ingestion of caffeine and other drugs known to increase alertness.

Behavioral effects of upper respiratory tract illnesses: a consideration of possible underlying cognitive mechanisms

Previous research has shown that both experimentally induced upper respiratory tract illnesses (URTIs) and naturally occurring URTIs influence mood and performance. The present study investigated possible cognitive mechanisms underlying the URTI-performance changes. Those who developed a cold (N = 47) had significantly faster, but less accurate, performance than those who remained healthy (N = 54). Illness had no effect on manipulations designed to influence encoding, response organisation (stimulus-response compatilibility) or response preparation. Similarly, there was no evidence that different components of working memory were impaired. Overall, the present research confirms that URTIs can have an effect on performance efficiency. Further research is required to identify the physiological and behavioral mechanisms underlying these effects.

Common Respiratory Tract Infections as Psychological Entities: A Review of the Mood and Performance Effects of Being Ill

The clinical manifestations associated with colds and influenza overshadow the equally important mood and performance impairments. While decreased alertness and increased anxiety can be considered side effects of symptomatology, symptoms alone may not be responsible for the psychomotor and attention deficits of colds and influenza, respectively. An alternative hypothesis, as proposed in this review, suggests that the immune response, in the form of a cytokine cascade, may be responsible for both the physical and psychological symptoms. In particular, patterns of cytokine production for each infection will dictate the symptoms and performance deficits both within and between viruses. This hypothesis can be extended to incorporate infectious mononucleosis, as well as colds and influenza. The efficacy of symptom‐based overthe‐counter medications is then called into question.

Effectiveness of alcohol-based hand disinfectants in a public administration: impact on health and work performance related to acute respiratory symptoms and diarrhoea

Background

The economical impact of absenteeism and reduced productivity due to acute infectious respiratory and gastrointestinal disease is normally not in the focus of surveillance systems and may therefore be underestimated. However, large community studies in Europe and USA have shown that communicable diseases have a great impact on morbidity and lead to millions of lost days at work, school and university each year. Hand disinfection is acknowledged as key element for infection control, but its effect in open, work place settings is unclear.

Methods

Our study involved a prospective, controlled, intervention-control group design to assess the epidemiological and economical impact of alcohol-based hand disinfectants use at work place. Volunteers in public administrations in the municipality of the city of Greifswald were randomized in two groups. Participants in the intervention group were provided with alcoholic hand disinfection, the control group was unchanged. Respiratory and gastrointestinal symptoms and days of work were recorded based on a monthly questionnaire over one year. On the whole, 1230 person months were evaluated.

Results

Hand disinfection reduced the number of episodes of illness for the majority of the registered symptoms. This effect became statistically significant for common cold (OR = 0.35 [0.17 - 0.71], p = 0.003), fever (OR = 0.38 [0.14-0.99], p = 0.035) and coughing (OR = 0.45 [0.22 - 0.91], p = 0.02). Participants in the intervention group reported less days ill for most symptoms assessed, e.g. colds (2.07 vs. 2.78%, p = 0.008), fever (0.25 vs. 0.31%, p = 0.037) and cough (1.85 vs. 2.00%, p = 0.024). For diarrhoea, the odds ratio for being absent became statistically significant too (0.11 (CI 0.01 - 0.93).

Conclusion

Hand disinfection can easily be introduced and maintained outside clinical settings as part of the daily hand hygiene. Therefore it appears as an interesting, cost-efficient method within the scope of company health support programmes.

Trial registration number

ISRCTN96340690

Selective effects of upper respiratory tract infection on cognition, mood and emotion processing: a prospective study

Observational and experimentally induced infection studies show that upper respiratory tract infections (URTI) affect mood and cognition. This study tested the effects of naturally occurring URTI on cognition, mood and emotional processing, using a prospective design, with a broader array of tests than previous research, and with well matched control participants. Eighty participants (42 younger, M age 20.3 years; 38 older, M age 64.3 years) underwent neuropsychological assessment at baseline. Once a participant had URTI symptoms, s/he and a healthy, matched participant were retested. The Cognitive Drug Research computerised assessment battery was used to assess Power and Continuity of Attention, Quality of Episodic and Working Memory, Speed of Memory, and mood. Additionally, emotional processing was measured on matching of emotionally-negative faces with faces and faces with labels. Forty-two of 80 participants were matched (21 well, 21 ill). Well participants improved in Speed of Memory and face-label reaction time. Despite a lack of fever, ill participants demonstrated significantly smaller improvements. Older participants reported feeling less alert if ill, and less stressed if well, than at baseline. All ill participants reported less contentment than at baseline than well participants. Severity of URTI symptoms correlated with changes in Speed of Memory and mood. Even without fever, infectious disease produces large disturbances in speed of cognitive processing, particularly that reflecting retrieval from memory, and these effects are more marked in older participants. URTIs also affect mood. Future studies need to examine the role of inflammatory molecules and the brain regions implicated in mediating these findings.

Antidepressant reversal of interferon-alpha-induced anhedonia

Interferon-alpha(IFN-alpha) is used clinically in the treatment of several pathologies such as hepatitis C and various cancers. The positive therapeutic potential is however often limited by negative secondary effects which include major depression, one of the cardinal symptoms of which is anhedonia which has been operationalized as a decreased sensitivity to rewards (inability to experience pleasure). Previous studies have demonstrated the existence of anhedonia in rats following an acute injection of IFN-alpha at doses corresponding to those used in clinical applications. If this previously demonstrated anhedonia is indeed part of a depression syndrome in rats, this behavioural symptom should be reversible by the administration of antidepressants. The objective of the present experiment was to determine whether two commonly used antidepressants (desipramine and fluoxetine) were effective in ameliorating IFN-alpha-induced anhedonia in rats. The experiment consisted of two phases. In the first, the effects of daily systemic injections of 104 units/kg of IFN-alpha (or vehicle) were evaluated with the three-bottle (1%, 8%, and 32%) sucrose-consumption test. In the second phase of the experiment, in addition to continued injections of IFN-, different groups received daily injections of desipramine (7.5 mg/kg ip), fluoxetine (7.5 mg/kg ip), or vehicle. The IFN-alpha injections during Phase 1 resulted in clear anhedonia, as expressed by increased consumption of the 32% solution and decreased consumption of 1% over the 33 days of this phase. After 15 days of antidepressant treatments, 32% sucrose consumption returned to baseline values. We have therefore confirmed that IFN-alpha-induced anhedonia is susceptible to reversal following chronic antidepressant treatment and thus it may appear timely to consider the prophylactic use of such in particular patients prescribed IFN in the clinic.

After-effects of the common cold on mood and performance

The present study examined whether volunteers who had recently had common colds showed impairments in mood and performance in the weeks following the illness. All volunteers (n = 24) were tested when healthy to provide baseline data for simple and choice reaction time tasks, attention and memory tasks and ratings of mood. When participants developed a cold (n = 13) they returned to the laboratory so that the illness could be verified. When they were symptom free they returned to the laboratory and repeated the procedure. They then completed the study with a final session 1 week later. Volunteers (n = 11) who remained healthy over 10 weeks were recalled as controls and also repeated the procedures. The results showed that those who had recently had colds showed few impairments in mental performance and mood. Taken together with the results of previous studies, this suggests that after-effects of viral infection are largely restricted to severe illnesses such as infectious mononucleosis and influenza. After-effects of colds may occur but these probably reflect poor learning at the time of the illness.

Effects of upper respiratory tract illnesses on mood and performance over the working day

The present study examined whether volunteers with common colds showed impairments in objective and subjective indicators of alertness over the course of the working day. All the volunteers (n = 21) were tested when healthy to provide baseline data for simple and choice reaction time tasks, visual search tasks and ratings of mood. These measures were taken before work (08.30 hours), at lunchtime (13.00) and after work (17.30). When participants developed a cold (n = 6) they repeated the procedure. Volunteers (n = 15) who remained healthy were recalled as controls and also repeated the procedures. The results showed that those with colds had significantly slower simple and choice reaction times, and felt less alert, more tense and less sociable. The effects of having a cold on simple reaction time, alertness and anxiety increased over the day. This extends earlier research and shows that some of the effects of upper respiratory tract illnesses on mood and performance will depend on when assessments are made. These results also imply that performance and well-being at work will be impaired by upper respiratory tract illnesses.

Effects of an experimentally induced rhinovirus cold on sleep, performance, and daytime alertness

STUDY OBJECTIVES

There is accumulating evidence that the common cold produces impairments in psychomotor vigilance. This has led some investigators to hypothesize that such illnesses may also have disruptive effects on sleep. While several self-report studies suggest that viral illness may influence sleep parameters, no studies have assessed polysomnographically recorded sleep following viral infections.

DESIGN

Parallel control group comparison.

SETTING

Sleep laboratory in a large urban medical center.

PARTICIPANTS

Twenty-one men and women with susceptibility to the rhinovirus type 23.

INTERVENTIONS

Nasal inoculation with rhinovirus type 23.

MEASUREMENTS

Polysomnographically recorded sleep for five nights (2300-0700 h) post-viral inoculation. Twice daily (1030 and 1430 h) performance assessment during each experimental day using auditory vigilance and divided attention tasks. A multiple sleep latency test (MSLT) was performed daily for the duration of the study.

RESULTS

In symptomatic individuals, total sleep time decreased an average of 23 min, consolidated sleep decreased an average of 36 min, and sleep efficiency was reduced by an average of 5% during the active viral period (experimental days/nights 3-5) compared with the incubation period. Psychomotor performance was impaired. These changes were significantly greater than those observed in asymptomatic individuals.

CONCLUSIONS

The common cold can have detrimental effects on sleep and psychomotor performance in symptomatic individuals during the initial active phase of the illness.

Effects of the Common Cold on Subjective Alertness, Reaction Time, and Eye Movements

Abstract The present study examined whether volunteers with common colds showed impairments in objective and subjective indicators of alertness. All the volunteers (N = 81) were tested when healthy to provide baseline data for mood, simple and choice reaction time tasks, and an anti-saccadic eye movement task. When subjects developed a cold (N = 17) they returned to the laboratory and repeated the procedure. Volunteers (N = 64) who remained healthy over a 10-week period were recalled as controls. The results showed that those with colds felt significantly less alert and had significantly slower simple and choice reaction times and eye movements. This extends earlier research and shows that electrophysiological measures may also be of use in assessing the behavioral changes induced by upper respiratory tract illnesses.

Effects of the common cold on mood and performance

Previous research has shown that both experimentally-induced and naturally occurring upper respiratory tract illnesses (URTIs) influence mood and mental functioning. None of the previous studies of naturally occurring colds has conducted appropriate virological assays to determine the nature of the infecting agent. This is an essential methodological step in studies of malaise associated with URTIs. The aim of this research was to investigate the effects of naturally occurring colds on mood and objective measures of performance. This was done by first conducting a cross-sectional comparison of 37 healthy people and 158 volunteers with colds and then a longitudinal study in which 100 volunteers developed colds and 87 remained healthy. Virological techniques were used to identify infecting agents and comparisons made across the different groups. The results showed that having a cold was associated with reduced alertness and slowed reaction times. These effects were observed both for colds where the infecting virus was identified and those where it was not. Similar effects were obtained for both rhinovirus and coronavirus colds. One may conclude that upper respiratory tract illnesses lead to a reduction in subjective alertness and impaired psychomotor functioning. This was true for both illnesses where the infecting agent was identified and for those clinical illnesses where no virus was detected. It is now important to identify the mechanisms linking infection and illness with the behavioural changes. Similarly, the impact of these effects on real-life activities such as driving needs examining. Finally, methods of treatment need to be developed which not only treat the local symptoms of the illnesses but remove the negative mood and the performance impairments.

Influence of socioeconomic status on behavioral, emotional and cognitive effects of rubella vaccination: a prospective, double blind study

A double-blind prospective design was used to investigate the immediate and prolonged psychological effects of a specific viral infection, and the role of immune activation in mediating these effects. Subjects were 240 female teenager girls who were vaccinated with rubella vaccine. Based on analysis of levels of antibodies to rubella, subjects were divided into two groups. An experimental group (n = 60), which included subjects who were initially seronegative and were infected following vaccination, and a control group (n = 180), which included subjects who were already immune to rubella before vaccination. Compared with the control group and to their own baseline, low socioeconomic status (SES) subjects within the experimental group showed a significant increase in the severity of depressed mood, social and attention problems, and delinquent behavior. Ten weeks post-vaccination there were no differences between the experimental and control groups in serum levels of interleukin-1 beta, interferon-gamma, soluble interleukin-2 receptors (sIL-2r), and cortisol. However, a significant negative correlation was found between fatigue-related symptoms and sIL-2r levels in the experimental (r = -0.325), but not the control group (r = -0.046). These findings suggest that viral infection can produce prolonged behavioral, emotional and cognitive problems mainly in subjects belonging to the low SES.

The relationship between fatigue, psychological and immunological variables in acute infectious illness

OBJECTIVE

The aim of this paper is to explore the longitudinal relationships between physical and psychological symptoms and immunological factors following acute infective illnesses.

METHOD

Preliminary data from a prospective investigation of patients with serologically proven acute infectious illnesses due to Epstein-Barr virus (EBV), Ross River virus (RRV) or Q fever are reported. Patients were assessed within 4 weeks of onset of symptoms and then reviewed 2 and 4 weeks later. Physical illness data were collected at interview. Psychological and somatic symptom profiles were assessed by standardised self-report questionnaires. Cell-mediated immune (CMI) function was assessed by measurement of delayed-type hypersensitivity (DTH) skin responses.

RESULTS

Thirty patients who had been assessed and followed over the 4-week period (including 17 patients with EBV, five with RRV and eight with Q fever) were included in this analysis. During the acute phase, profound fatigue and malaise were the most common symptoms. Classical depressive and anxiety symptoms were not prominent. Initially, 46% of cases had no DTH skin response (i.e. cutaneous anergy) indicative of impaired cellular immunity. Over the 4-week period, there was a marked improvement in both somatic and psychological symptoms, although fatigue remained a prominent feature in 63% of subjects. The reduction in reported fatigue was correlated with improvement in the DTH skin response (p = 0.001) and with improvement in General Health Questionnaire (GHQ) scores (p < 0.01).

CONCLUSIONS

Acute infectious illnesses are accompanied by a range of nonspecific somatic and psychological symptoms, particularly fatigue and malaise rather than anxiety and depression. Although improvement in several symptoms occurs rapidly, fatigue commonly remains a prominent complaint at 4 weeks. Resolution of fatigue is associated with improvement in cell-mediated immunity.

Poor concentration and the ability to process information after glandular fever

The symptom of poor concentration and the ability to process information were measured prospectively in 245 subjects three times in the 6 months after glandular fever or an ordinary upper respiratory tract infection. The effects of the different infections, having a fatigue state, a psychiatric disorder, sleep disturbance, and estimates of premorbid intelligence were also assessed. The most frequent complaint of poor concentration and the worst information processing occurred at the onset of the infection, but these problems decreased over time, and were not related to each other. Multiple regression modeling showed that higher socioeconomic class and vocabulary IQ were associated with information processing ability at all three interviews. In contrast, logistic regression modeling showed that the symptom of poor concentration was associated with the severity of general psychiatric morbidity (CIS score) followed by suffering from a fatigue state. These results suggest that the ability to process information after these particular infections is related to estimates of premorbid IQ, whereas poor concentration is related independently to both psychiatric morbidity and a fatigue state, but not the particular infection itself.

Caffeine and the common cold

An experiment was carried out to determine whether caffeinated and decaffeinated coffee removed the malaise (reduced alertness, slower psychomotor performance) associated with having a common cold. One hundred volunteers were tested when healthy and 46 returned to the laboratory when they developed colds. Those subjects who remained healthy were then recalled as a control group. On the second visit subjects carried out two sessions, one pre-drink and another an hour after the drink. Subjects were randomly assigned to one of the following three conditions, caffeinated coffee (1.5 mg/kg caffeine/body weight), decaffeinated coffee or fruit juice. Subjects with colds reported decreased alertness and were slower at performing psychomotor tasks. Caffeine increased the alertness and performance of the colds subjects to the same level as the healthy group and decaffeinated coffee also led to an improvement. These results suggest that drugs which increase alertness can remove the malaise associated with the common cold, and that increased stimulation of the sensory afferent nerves may also be beneficial.

Investigation of the effects and aftereffects of naturally occurring upper respiratory tract illnesses on mood and performance

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.

Health psychology: psychological factors and physical disease from the perspective of human psychoneuroimmunology

This review addresses the importance of studies of human psychoneuroimmunology in understanding the role of psychological factors in physical illness. First, it provides psychologically and biologically plausible explanations for how psychological factors might influence immunity and immune system-mediated disease. Second, it covers substantial evidence that factors such as stress, negative affect, clinical depression, social support, and repression/denial can influence both cellular and humoral indicators of immune status and function. Third, at least in the case of the less serious infectious diseases (colds, influenza, herpes), it considers consistent and convincing evidence of links between stress and negative affect and disease onset and progression. Although still early in its development, research also suggests a role of psychological factors in autoimmune diseases. Evidence for effects of stress, depression, and repression/denial on onset and progression of AIDs and cancer is less consistent and inconclusive, possibly owing to methodological limitations inherent in studying these complex illnesses, or because psychological influences on immunity are not of the magnitude or type necessary to alter the body's response in these cases. What is missing in this literature, however, is strong evidence that the associations between psychological factors and disease that do exist are attributable to immune changes.

Are cytokines associated with neuropsychiatric syndromes in humans?

Traditional aetiological models in neuropsychiatry have placed little emphasis on the abnormal behavioural responses (decreased psychomotor activity, anorexia, weight loss, decreased social exploration and sexual behaviour, impaired cognitive function and increased somnolence) that are common to both psychiatric syndromes, notably depression, and the illness behaviour of sick animals. In recent years, the possible role of cytokines, as mediators of not only the immunological and metabolic responses to infection and inflammation but also a co-ordinated behavioural response, has been described. Further, a range of possible mechanisms for these effects has been postulated, notably involving corticotropin releasing factor (CRF) and prostaglandins of the E series (PgE) with the central nervous system (CNS). Here we outline a series of human clinical conditions where neuropsychiatric syndromes co-occur with a host response to infection or inflammation. These may be characterized by cytokine production (e.g. acute, recurrent and chronic viral illness, systemic autoimmune diseases and chronic fatigue syndrome). Other clinical situations characterized by exposure to or in vivo production of cytokines (e.g. treatment of chronic infections and malignancies, progression and/or recurrence of malignancies) are also discussed. We postulate that the stereotyped behavioural repertoire observed is mediated by cytokine-dependent mechanisms within the CNS. Systematic studies of the behavioural responses of such patient groups are suggested, noting specifically correlations between the time course and severity of immune and neuroendocrine and behavioural responses and dose-response effects.

A comparison of the acute effects of a low dose of alcohol on mood and performance of healthy volunteers and subjects with upper respiratory tract illnesses

An experiment was carried out to determine whether a low dose of alcohol produced different behavioural effects in healthy volunteers to those suffering from an upper respiratory tract illness. Ninety-nine subjects were tested, with 48 subjects being assigned to the alcohol condition and 51 to the juice only condition. A dose of 1.5 ml of vodka per kg body weight was used and the alcohol manipulation was double-blind. Approximately half of the subjects in each condition were healthy and the others had upper respiratory tract illnesses, probably colds. Subjects with colds reported an increase in negative affect and were slower at performing psychomotor tasks. Few main effects of alcohol were obtained. Of major interest were the interactions between health status and alcohol conditions. The alcohol improved the mood of healthy subjects but produced greater negative moods in subjects with colds. Similarly, performance of selective and sustained attention tasks showed different effects of alcohol in healthy and ill subjects.

The mind and the immune system

Stress-induced brain-mediated immunoregulation is effected by two pathways: autonomic outflow and (neuro)endocrine outflow. Particular attention is given to the interaction-effects of chronic an acute stress. Recent data have established that cells of the immune system produce neuro-peptides and hormones. In concert with cytokines released by these immune cells the brain can be informed on the nature of ongoing immune activity. The significance of conditioning of immune responses is discussed.

Infection, nutrition and cognitive performance in children

The paper considers briefly the nature of cognition and its relationship to intelligence. The information processing model of human cognition is outlined and IQ and DQ are explained. The literature dealing with the effects of malnutrition and parasitic infection on cognitive performance and development in children is selectively reviewed. A speculative hypothesis concerning the psychological effects of parasitic infection is sketched and brief consideration is given to models and measures in research on development.

A view from the Common Cold Unit

I have been asked to stand back and describe in broad terms the view I have had of common colds--probably the most frequent of acute human diseases and a long-lasting scientific problem--and in particular our recent work on antivirals. I should be able to do this for two reasons. Like everyone else I have suffered from colds, but in addition I have been studying the problem from the virological and clinical point of view for over 35 years--for the last 31 at the Common Cold Unit, Salisbury. As a result I may have problems with perspective--it is not possible to give a personal view and at the same time to describe something from every possible angle, and quite impossible to be comprehensive, but I have done my best and readers will make their own judgements and corrections.

The common cold, pattern sensitivity and contrast sensitivity

Results from two studies involving challenge with respiratory syncytial viruses showed that volunteers who developed colds were more sensitive to a visually distracting pattern presented prior to virus challenge than were volunteers who did not get a cold. Volunteers with sub-clinical infections reported more illusions after virus challenge than they had done before, whereas uninfected volunteers and those with colds tended to report fewer illusions on the second test. These effects did not occur when volunteers were challenged with either a coronavirus or rhinovirus. Overall, the results confirm that behavioural measures may be related to susceptibility to subsequent illness, and that viral infections may influence visual perception. They also show that the effects vary according to the nature of the infecting agent, which agrees with results from studies looking at other aspects of behaviour.

The effects and after-effects of interferon alpha on human performance, mood and physiological functions

The effects of three doses of interferon alpha (IFNα, 1.5 Mu, 0.5 Mu and 0.1 Mu) on performance, mood and physiological function were examined in a double-blind placebo controlled trial. The subjects given an injection of 1.5 Mu showed symptoms which closely resembled those seen in influenza, although most of the symptoms had gone by the next day. All of the doses of IFN reduced subjective ratings of alertness, but again this effect was only apparent on the day of challenge. Subjects given the 1.5 Mu injection were slower on two of the performance tasks (a simple reaction time task and a pegboard task) both on the day of challenge and the following day. None of the other tasks in the battery was impaired by any of the doses of IFN, either on the day of challenge or the following day. These results suggest that IFNα has selective effects on performance, and it is possible that IFN-induced changes in CNS function provide a mechanism through which viral infections influence behaviour.

The effects of caffeine, impulsivity and time of day on performance, mood and cardiovascular function

Two experiments were carried out to examine the effects of caffeine on performance, mood and cardiovascular function. The results showed that the effects of caffeine depended on the dose, time of administration, the function being examined and the impulsivity of the subject. Changes in blood pressure were only observed when a high dose (3 mg/kg) was used. The effects of this dose on performance depended on the impulsivity of the subject, with high impulsives performing worse in the de-caffeinated condition but getting a greater benefit from the caffeine. The high dose of caffeine also removed the post-lunch dip in sustained attention. The second experiment, which used a lower dose of caffeine (~60 mg), failed to demonstrate any caffeine x impulsivity or caffeine x time of day effects on performance. However, caffeine improved performance on a logical reasoning task and caffeine x time of day x impulsivity effects were found in analyses of visual search tasks. The mood data also support the view that the effects of caffeine depend on a combination of factors similar to those outlined for performance.

Effects of zinc gluconate and nedocromil sodium on performance deficits produced by the common cold

Two studies are reported on the effects of drugs on the performance impairments induced by experimentally- produced colds. The first study examined the effects of zinc gluconate on choice reaction time, and showed that the zinc removed the cold-induced performance impairment. The second experiment used nedocromil sodium and, again, the drug was effective in reducing the drop in performance observed in volunteers with colds. While the precise mode of action of these compounds is unclear it is speculated that one mechanism involves changes in trigeminal stimulation, and this could be responsible for both the clinical efficacy and CNS effects of these drugs.

Effects of experimentally induced colds on aspects of memory

Four experiments were carried out to investigate the effects of experimentally-induced colds on various aspects of memory of 27, 47, 39, and 30 adults. Free recall, digit span, and retrieval from semantic memory were unaffected by having a cold. Immediate recognition of important information from a story was impaired in subjects with colds, which suggests they were less able to follow the theme of the story. In contrast to this, volunteers with colds had better recognition of information from a story learned prior to the virus challenge.

Respiratory virus infections and performance

Minor illnesses, such as colds and influenza, are frequent, widespread and a major cause of absenteeism from work and education. Yet the clinical symptoms of such illnesses may not be so great as to stop people from working or from carrying out everyday activities. It is therefore important to determine whether these viral infections alter central nervous system function and change performance efficiency. Data on this topic are almost non-existent, which in part reflects the difficulties inherent in carrying out such studies. In real life it is almost impossible to predict when such illnesses will occur, and difficult to establish which virus produced the illness. This problem was overcome by studying experimentally induced infections and illnesses at the Medical Research Centre (MRC) Common Cold Unit in Salisbury. Results from this research programme show that: (i) colds and influenza have selective effects on performance; (ii) even sub-clinical infections can produce performance impairments; (iii) performance may be impaired during the incubation period of the illness; (iv) performance impairments may still be observed after the clinical symptoms have gone. These results have strong implications for occupational safety and efficiency and it is now essential to assess the impact of naturally occurring colds and influenza on real-life activities.

The effects of menthol on reaction time and nasal sensation of airflow in subjects suffering from the common cold

The effects of sucking a lozenge containing 11 mg L-menthol on reaction time and nasal sensation were investigated in a double blind trial on 60 subjects suffering from the common cold. Reaction time was determined by measuring the response time to a stimulus presented on a microcomputer screen and nasal sensation was scored on a visual analogue scale. Menthol ingestion compared to placebo caused a significant increase in nasal sensation of airflow which persisted for up to 30 min. The simple and choice reaction times measured before ingestion of the lozenge were similar to those found in healthy uninfected subjects and there was no change in reaction time after ingestion of menthol.

Effects of interferon alpha on performance in man: a preliminary report

The effects of three doses of interferon alpha (1.5 Mu, 0.5 Mu and 0.1 Mu) on performance were studied. The injection of 1.5 Mu IFN produced symptoms and performance changes which closely resembled those found in volunteers with influenza. Specifically, volunteers were slower at responding when they were uncertain when a target stimulus would appear, but were not impaired on a pursuit tracking task or syntactic reasoning task. The results suggest that interferon-induced changes in CNS function provide a plausible explanation for the selective effects of influenza on performance.