Personality and risk of adult asthma in a prospective cohort study
Introduction
Personality is considered to underlie consistent patterns of behaviors, thoughts and feelings, and predicts both psychological and physical health [1], [2]. One widely recognized approach to assess personality is the five-factor model (“Big Five”), which differentiates the five bipolar dimensions neuroticism, extraversion, agreeableness, conscientiousness, and openness to experience [3]. Individuals scoring high on neuroticism are characterized by emotional instability and proneness to experiencing distress; high extraversion is conceptualized as sociability and an open expression of impulses; high agreeableness is manifested in behavioral characteristics that are perceived as kind and cooperative, while high conscientiousness reflects a tendency to be organized, dependable and to exhibit self-discipline Finally, openness reflects the degree of curiosity and a preference for novelty and variety of experience [3], [4].
Several of these traits have been found to predict health outcomes, which may involve at least two underlying pathways [2]: First, personality affects how stress is perceived and dealt with [2], [5], [6], and, as a consequence, may determine one's physiological response to stress [7], [8]. Such responses, in turn, are assumed to contribute to the development of disease, especially if those stress responses are chronic. Second, personality traits have been identified as determinants of health behaviors, such as smoking and a sedentary lifestyle [9], [10], which represent major risk factors for chronic disease. Since psychological stress and health behaviors have been implicated in the etiology of asthma [11], [12], [13], one may hypothesize that personality traits predict asthma.
To date, two prospective studies, from Finland [14] and from Germany [15], have examined the relationship between personality traits and incident asthma. Both investigations were restricted to only two of the Big Five traits, i.e., neuroticism, and extraversion. In the German cohort study, published by our group, neuroticism predicted asthma, but extraversion did not [15]. We hypothesized that elevated neuroticism may contribute to asthma due to its property of predisposing individuals to experiencing distress [15]. By contrast, the Finnish study found that only high extraversion scores were associated with an increased risk of asthma among women, which was partially attributed to poor health behavior (i.e., smoking) [14]. Thus, the limited number of longitudinal studies on the relationship of neuroticism and extraversion with asthma yielded conflicting results.
It appears warranted to also examine the other Big Five traits as potential predictors of asthma, in particular conscientiousness and agreeableness. There is emerging consensus that conscientiousness is a powerful predictor of health across the life course [1]. High conscientiousness may affect health in part through engagement in healthy lifestyles [1], [10], [16], [17] and through better coping [18], and consequently lower levels of stress [19], [20]. In particular, it has been hypothesized that individuals with high levels of conscientiousness are more likely to choose healthier social and physical environments [1] and that they may be more likely to prepare for predictable stressors [6]. Also, conscientious individuals may be less likely to behave impulsively thereby avoiding stress due to inconsiderate decisions in interpersonal, financial, and health-related domains of life [6]. Hence, we hypothesize that increased conscientiousness is associated with a reduced risk of asthma.
Likewise, we hypothesize that elevated levels of agreeableness exert protective effects on asthma risk. High agreeableness is associated with less interpersonal conflict [21], stronger social networks [22], a higher probability of receiving social support [6], [19] and with better utilization of such support to cope in particular with interpersonal stress [6]. Since interpersonal stressors (e.g., relationship problems) and low social support have been associated with incident asthma [15], [23], [24], the risk of asthma may decrease with increasing levels of agreeableness. The remaining trait, “openness to experience”, has typically been found to be unrelated to mental or physical health [6], [25], [26], [27]. We therefore do not expect an association between openness to experience and asthma risk.
In summary, evidence on the relationship between personality and incident asthma is sparse, being limited to two prospective studies [14], [15]. These studies investigated only neuroticism and extraversion and yielded inconsistent findings. Expansion of research efforts to consider the remaining traits appears promising however. It was therefore the aim of this study to examine the associations of all the Big Five traits with incident asthma.
Section snippets
Study population
We drew on data from the German Socio-Economic Panel [GSOEP] study [28]. Since 1984, interviews or questionnaires were used annually to collect data for the GSOEP. Briefly, a random sample of German household was identified and each individual living in a selected household and who was aged 17 years or above was eligible for participation. The GSOEP complies with national laws and informed consent was obtained from all participants [29]. The current study combined primarily the 2009 (baseline)
Results
The cumulative incidence of adult asthma equalled 1.75% (214 cases), which is in line with reports from other epidemiological studies [39]. As shown in Table 1, the study participants were middle-aged, had received, on average, 12 years (SD [standard deviation] = 2.7) of formal education, and about half of the sample was female. Bearing in mind the potential scoring range of 3 to 21, scores on conscientiousness were fairly high.
Table 2 shows the results from the prospective analysis. Neuroticism
Discussion
The present study examined prospective relationships between the Big Five personality traits and incident asthma. Only neuroticism showed a positive, statistically significant, and meaningfully pronounced relationship with incident asthma. This association was independent of numerous potential confounders. We neither observed effect-modification by sex nor interactions between personality traits.
The observation of a positive association between neuroticism and asthma is consistent with findings
Conflict of interest
The authors declare that there are no conflicts of interest.
Acknowledgments
We are grateful to the Deutsches Institut für Wirtschaftsforschung (DIW), Berlin, for the provision of the German Socio-Economic Panel (GSOEP) data employed for the current manuscript.
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