This ESRC funded research involved two studies at the School of Psychology at Cardiff University. The first study recruited 498 healthy students who were asked to return if they developed an upper respiratory tract infection within six to 96 hours of symptoms developing. 'The 188 participants who developed colds were more likely to drink and smoke than those who remained healthy which confirms previous findings' says Professor Andy Smith, author of the studies. 'Not only that but smokers and participants who had a lot of stress in their lives became ill more quickly than non smokers' he adds.
The second study was based on participants keeping a diary for 10 weeks and recording illness and problems of memory and attention. A hundred volunteers from the community took part and were sub divided into those who reported a single illness and those who reported more than one. 'We found that those who had more than one illness were less likely to eat breakfast and consume alcohol' says Professor Smith. 'Those who developed multiple illnesses had also endured more negative life events in the last 12 months' he adds.
Both studies also showed that volunteers who were ill reported more negative mood, slower response times and more problems sustaining attention. The extent of the performance impairments were not related to symptom severity nor to the factors associated with increased susceptibility to illness.
'In summary the results from these two large scale studies have provided evidence of the effects of upper respiratory tract infections on mood and performance' says Professor Smith. 'They have also shown that psychosocial factors and health related behaviours may well influence susceptibility to colds and flu and the nature and extent of the symptoms. However, the performance changes do not reflect the severity of the symptoms or the factors associated with increased susceptibility to colds' he adds.
'Further research on the impact of minor illnesses in industry and education is now needed' says Professor Smith. 'Awareness of the effects of performing whilst ill should also be increased and possible counter measures considered' he adds. 'We are now beginning to understand much more about the mechanisms underlying these effects and further study of the cognitive process which are impaired, the changes in brain chemistry which take place and the role of mediating factors is now needed. Medication also needs to be developed which not only reduces symptoms but improves the performance and mood of people who have minor illnesses such as the common cold' he adds.