Those who are the most conscientious and careful, though, are most likely to have a weaker immune system response.
The research found no evidence, though, that a tendency towards negative emotions was associated with poor health.
The study, published in the snappily titled journal Psychoneuroendochrinology, gave personality tests to 121 health adults (Vedhara et al., 2014).
Along with assessing the five major personality factors — extraversion, neuroticism, openness, agreeableness and conscientiousness — participants had blood samples taken to measure genetic factors known to be important in immune function.
Professor Kavita Vedhara, who led the study, explained the results:
“Our results indicated that ‘extraversion’ was significantly associated with an increased expression of pro-inflammatory genes and that ‘conscientiousness’ was linked to a reduced expression of pro-inflammatory genes.
In other words, individuals who we would expect to be exposed to more infections as a result of their socially orientated nature (i.e., extraverts) appear to have immune systems that we would expect can deal effectively with infection.
While individuals who may be less exposed to infections because of their cautious/conscientious dispositions have immune systems that may respond less well.
We can’t, however, say which came first.
Is this our biology determining our psychology or our psychology determining our biology?”