In a study exploring the link between self-reported health and immunity, American researchers demonstrated that if you think your health is not very good, you have a greater susceptibility to infection.
Doctors should perhaps ask their patients to self-rate their health at the beginning of a consultation. So suggest the conclusions of this new study, published in the November-December 2015 edition of the journal Psychosomatic Medicine.
Psychologists at Carnegie Mellon University in the US have shown that the self-rated health of adults aged 18 to 55 could be an indicator of the likelihood of catching a cold. Self-Rated Health is an indicator commonly used to measure a person's opinion of their general state of health.
The researchers selected 360 healthy adults with an average age of 33, whom they asked to self-assess their health using a questionnaire. Each participant could choose among "excellent," "very good," "good," "fair" or "poor." None of them gave the last answer, as they had all been selected for their good health, and only 2 per cent answered "fair."
The volunteers were then exposed to a virus that causes the common cold and were monitored for five days to study the development of illness. The team noted that nearly a third of the participants developed a cold. The participants who self-assessed their health as being "very good," "good" or "fair" were twice as likely to have been affected by the virus as those who self-reported their health as "excellent."
For the researchers, this increased risk of catching a cold was not due to the infection, but rather the increased probability of objective signs of disease once it had developed. Variables such as a poor lifestyle, high stress levels, negative emotions and socio-economic factors did not account for this phenomenon.
According to Sheldon Cohen, the study's main author, the explanation for this connection between self-assessed health and susceptibility to infection could be indicators -- sensations, feelings, diffuse symptoms -- of dysfunctions in the immune system that warn us that something is wrong even before the clinical symptoms appear. They could be things we know about our body that are not detectable by a doctor.
This study is one of the first to suggest that people are able to predict how their immune system will respond to a virus or other health risks, and it contributes to the understanding of the biological mechanisms of the link between morbidity and self-rated health.