‘I told you I was ill! Being neurotic can be GOOD for your health after all’ the Daily Mail reports.
The news comes after a study in which researchers investigated what affect on health the ‘Big 5 personality traits’ had. The ‘Big 5’ are based on a model that an individual’s personality can be assessed using five measurements of attitude and behaviour:
The research included 1,054 people who were initially asked to complete a survey assessing their ‘Big 5 personality traits’.
About two years later, researchers assessed their medical health and lifestyle (for example smoking and alcohol intake) and measured blood levels of the protein interleukin-6 (IL-6). This protein is made by the immune system cells and stimulates the body’s immune response to infection and tissue damage.
The researchers found that both high levels of conscientiousness and high levels of neuroticism were associated with lower IL-6 levels . This type of personality may fit what a previous researcher has labelled ‘the healthy Neuroticist' – somebody who worries about their health so they live a healthy lifestyle and / or seek medical advice every time they think something is wrong.
While interesting, there is little in practical advice that can be concluded from this study. The idea that lower levels of IL-6 automatically equate to good health is both simplistic and unproven.
Also, the study did not assess the effects that neurotic traits could have on mental health.
This study was conducted by researchers from the University of Rochester School of Medicine and Dentistry, The Center on Aging and the Life Course at Purdue University, West Lafayette, United States.
The study was published in the peer reviewed medical journal: Brain, Behaviour and Immunity.
The Mail’s report was generally representative of the findings of the paper, though the findings are not worthy of the sensationalist headlines.
Also, the paper does not make clear that the lowest levels of the IL-6 were not found in all people with high levels of neurotic traits. The lowest levels were in fact found in people with both high neuroticism and conscientiousness (the so-called ‘healthy Neuroticists’).
This was an analysis of data collected as part of The National Survey of Midlife Development cohort study in the U.S. (MIDUS) which randomly recruited English-speaking adults living in the US.
The research assessed whether the ‘Big 5’ personality traits are associated with the levels of one biological ‘marker’ which indicates that there is inflammation in the body, called interleukin 6 (IL-6). The ‘Big 5’ traits are neuroticism, extraversion, openness, conscientiousness and agreeableness.
Previous studies are said to have found an association between levels of neuroticism and of conscientiousness, and with inflammatory markers. Inflammatory markers are a series of proteins found in the blood that can provide a broad, but certainly not definitive, assessment of levels of damage and infection inside the body.
People with very high levels of inflammatory markers may be be at increased risk of developing a chronic disease, such as heart disease.
The researchers in the current study wanted to check these findings in a large sample and to look at whether the levels of neuroticism and conscientiousness interact with each other to influence the levels of inflammatory markers. They also looked at the effect of taking into account medical factors which might be influencing the results, such as having chronic conditions, taking medications, or being overweight or obese.
Although cohort studies can suggest an association between factors by themselves, they cannot prove cause and effect between the factors assessed, in this case personality and the biomarkers. This requires an accumulation of a large body of evidence from different types of studies, all supporting the theory that one factor causes the other.
This analysis was part of The National Survey of Midlife Development in the U.S. (MIDUS) cohort study which randomly selected English-speaking adults living in the US for recruitment.
Between 1995 and 1996 the MIDUS study recruited 7,108 US citizens, aged 25–74 years.
Data for the current study comes from the second follow-up point when data was collected between 2004 and 2009. Of the original sample, 75% (4,963) agreed to participate in the second follow-up, but complete data on the variables of interest was only available for 1,054.
The age range of these participants was 34-84 years, 56% were female and the majority were of white ethnic origin.
Personality was assessed using a self-administered tool which assessed the ‘Big 5’ personality traits.
Participants were asked how applicable they thought each of 26 adjectives were to themselves on a scale ranging from one (not at all) to four (a lot). The adjectives were:
Scores were calculated for each participant to look at which traits were predominant.
About two years later, fasting blood samples were taken to measure the blood levels of the inflammatory marker IL-6. The participants also completed health assessments which included body mass index (BMI), lifestyle history (such as smoking and alcohol), current medical illnesses and medications, and were asked about their education history.
Statistical models were used to look at associations between the personality traits and IL-6 levels, adjusting for various other health variables the researchers had gathered information on.
Both conscientiousness and neuroticism were individually associated with lower blood levels of IL-6.
The relationship between neuroticism and IL-6 was dependent on levels of conscientiousness.
In people with low levels of conscientiousness there was no relationship between neuroticism and IL-6.
In people with high levels of conscientiousness, higher levels of neuroticism were associated with significantly lower levels of IL-6.
Each successive adjustment for medical illnesses, medications, health behaviours and BMI gradually reduced the strength of the interaction between conscientiousness and neuroticism, though it still remained statistically significant.
The researchers found that agreeableness, on the other hand, was associated with higher IL-6 levels, though this particular association did not remain statistically significant after adjustment for demographic factors.
The researchers concluded that ‘consistent with prior speculation, average to higher levels of neuroticism can in some cases be associated with health benefits’. They found that this relationship between higher levels of neuroticism and lower levels of inflammatory markers is only found in people who also have high levels of conscientiousness.
There is little that can be concluded from this research. The study does have strengths, including a fairly large, representative sample of the US population and the fact that they collected various health data from them prospectively. The study also used methods to assess the ‘Big 5’ personality traits that are reported to have been tried and tested and are accepted as valid.
Although cohort studies can suggest an association between factors, by themselves they cannot prove cause and effect between the factors assessed – in this case personality and the biomarkers – as other factors may be having an effect.
The researchers did try to take some of these factors into account, but it is difficult to completely remove their influence, and therefore there may be other unrelated factors which are having an effect.
Also, IL-6 was not measured at the start of the study when personality was assessed, so the researchers could not say for certain that people with different personality traits did not already have higher or lower levels of IL-6 at the start of the study.
In addition, IL-6 is only one protein involved in the body’s immune response, and lower levels of this single inflammatory marker in the blood does not necessarily mean that a person has a better health outlook.
Much longer-term studies which look at health outcomes as well as IL-6 levels would be needed to investigate this.
The study certainly does not prove that being neurotic can be ‘good’ (or bad) for your health. While feeling anxious all the time may make you more health conscious and more likely to seek medical advice, it can also impact on your health. Anyone who is feeling low, anxious or panicky all the time should seek medical advice.