The influence of personality traits on perception of pain in older adults – Findings from the Swedish National Study on Aging and Care – Blekinge study

1 Introduction

The experience of pain is associated with tissue damage or described in terms of such damage [1]. As pain includes both sensory and emotional components, personality affects the experience of pain [2]. Research on twins suggests that the perception of pain is related to personality [3].

Personality factors have a greater influence on suffering than on pain intensity [4]. The ways individuals differ are summarized in the five factor theory of personality (FFT): Neuroticism (), Extraversion (E), Openness (O), Agreeableness (A) and Conscientiousness (C) [5]. The FFT is a model for investigating the relationship between personality and health [6].

N represents the individual’s tendency to feel nervous, worry and wish to avoid harm. Psychological distress has a strong association with N [7]. In adult fibromyalgia patients (24-62 years) N was found to have a strong connection with both pain catastrophizing and pain anxiety [8]. N is associated with unpleasantness but not with pain intensity [4].

E is characterized by being social and willing to enter into contact with others. In a study of adults aged 60 and over, this trait was reported to be high among the oldest old and, together with other factors, suggested as contributing to the rapidly increasing rate of very old people [9]. The study found associations between E and adaptation to the challenges of the oldest old [9]. Although the association between E and longevity has been discussed, no evidence has been found when comparing younger and older individuals as in the Health and Lifestyle survey [10].

Imagination, aesthetic sensitivity, attentiveness to inner feelings and intellectually curiosity is one description of the trait O, which has also been described as a source of life satisfaction after retirement [11]. Individuals with this trait wish for sensory stimulation, such as viewing art, listening to music, reading literature and poetry, as well as variety in everyday life. Individuals with a low score on this trait are considered conventional and traditional. The combination of O and N was found to be associated with high anxiety/depression scores among individuals with chronic conditions [12].

Individuals who have a high score on A usually have positive social interactions, cooperate well in groups and help others. A has been related to sadness in a study including both younger and older adults in the USA [13]. Another characteristic of A is the tendency to be compassionate, although A was found to be negatively related to distress in an interpersonal context in patients with low back pain [14].

Characteristics of trait C include competence, self-discipline and impulse control. This trait is often common among people with a healthy life-style, i.e. individuals who normally exercise and avoid excessive alcohol consumption and smoking. The use of Health Care, i.e. annual check-ups and compliance with doctors’ advice, can to some extent explain the relationship between C and perceived health among the older adults [15]. Individuals who have a high score on C tend to be organized, a typical characteristic of this group being to-do lists. They tend to be happy with life and the C-trait is considered to have a positive relationship with subjective well-being. C is a predictor of longevity, even when adjusted for gender and educational level [16].

It has been suggested that personality traits influence psychosocial functioning in patients with pain. N was demonstrated to constitute a vulnerability factor, predisposing patients to greater fear of pain and higher pain severity [17]. Martinez et al. concluded that N and C were predictors of pain catastrophizing and that N, O, and A were significant predictors of pain anxiety [8]. Psychological treatment provides the same level of pain relief as surgery among low back pain patients with high N scores [18]. In the past decade, the FFT of personality has gained wide acceptance [19]. A vulnerability model indicated an increase in the risk of N in individuals with low educational level [20]. Higher levels of E and C may be associated with a reduced risk of disability in old age [21].

Insomnia and age are associated with pain [22]. Financial status has been demonstrated to be associated with pain experience. Education is related to personality and could be assumed to be associated with pain [23]. In 2003 about 15.9% of adults in Sweden had studied at university level [24]. Insomnia has been shown to relate to quality of life (QoL) among men [22,25]. Women more often complain of insomnia but research has suggested that this may be caused by behavioural factors [26]. All types of insomnia are prevalent in the geriatric population [27]. Coping strategies vary according to personality trait, thus insomnia is assumed to be associated with personality [28].

The aim of the present study was to, in a gender perspective, investigate possible associations between perceived pain and the personality among persons aged 60 years and older.

2 Methods

3 Results

Pain was reported by 769 (54.8%) individuals, 496 (64.5%) women and 273 (35.5%) men (p<0.001). Pain intensity was reported by 704 individuals, 443 (89.3%) women and 261 (95.6%) men and distributed as follows; women: mild 63 (14.2%); moderate 260 (58.7%); severe 120 (27.1%) and men: mild 55 (21.1%); moderate 141 (54.0%); severe 65 (24.9%).

Mean age in the group of women reporting pain was 76.6 years compared to the group of women with no pain who had a mean age of 79.2 years (p<0.003). Men reporting pain had a mean age of 74.7 years compared to 75.9 years for those without pain.

Insomnia was reported by 304 (39.9%) in the pain group and by 110 (21.5%) of those without pain (p < 0.001). Women with pain, 234/493 (47.5%), most commonly reported insomnia followed by women without pain, 71/248 (28.6%). Among men, the corresponding figures were 70/209 (26.0%) and 39/263 (14.8%).

Among women, N was associated with pain (OR 1.05, CI 1.03-1.08) (Table 1a). In men, both N (OR 1.03, CI 1.002-1.07) and O (OR 1.04, CI 1.005-1.08) were associated with pain (Table 1b). No relationship between personality traits and pain intensity was detected (n.s.).

Significantly related personality traits were then tested based on gender by means of multivariate forward logistic regression in models adjusted for age, insomnia, financial status and educational level (Tables 2a and 2b).

In model 1, the strength of association between pain and the traits was about the same for women and men. In women, the trait N was associated with pain (OR 1.06, CI 1.03–1.09). In men, both the trait N (OR 1.04, CI 1.01–1.06) and O (OR 1.04, CI 1.001–1.07) were associated with pain.

In model 2, no association with younger age was found for either men or women.

In model 3, the OR for N remained weak but significant for both sexes. In women, insomnia had the highest odds ratio for pain (OR 2.18, CI 1.52–3.12) followed by N (OR 1.05, CI 1.03–1.08) and younger age (OR 1.02, CI 1.001–1.04). In men, the OR for insomnia was (OR 1.99, CI 1.25–3.16) followed N (OR1.03, CI 1.002–1.06) and O (OR 1.03, CI 1.001–1.07).

In model 4, no association with low economic status was found for either men or women and no changes in relationship between pain and personality traits, age or insomnia was noted.

In model 5, in the final model for women, insomnia still yielded the highest odds ratio for pain (OR 2.19, CI 1.52–3.15) followed by low educational level (OR 1,59 CI 1.07–2.36). The trait of N (OR 1.05, CI 1.02–1.08) and belonging to the younger group of older adults (OR 1.02, CI 1.005–1.04) remained stable. A strained financial situation was not significantly related to pain (Table 2a).

In the final model for men, insomnia was found to have the highest odds ratio for pain (OR 1.98, CI 1.24–3.15) followed by the traits of N (OR 1.03, CI 1.002–1.06) and O (OR1.03, CI1.001–1.07). Belonging to the younger group of older adults, having a strained financial situation and low educational level were not significantly related to pain. The relationship between personality traits and pain was only affected to a minor extent by insomnia (Table 2b).

4 Discussion

This study adds to knowledge of pain in the elderly population and suggests that older adults with pain may share particular personality traits. The relationship between pain and personality seems to be equally strong among both sexes, although different traits are present in women and men. The result indicates about the same strength of association between pain and the trait of N in women and between pain and the traits of N and O among men. However, the OR values regarding personality traits are statistically significant but generally very low in the older population compared with younger pain patients [7, 8]. Therefore, interpretation of the results should be made with care. It is important to bear in mind that a personality trait is a multi-dimensional construct and although attempts have been made to classify human beings into stereotypical categories, “The Big Five” traits only reveal the dominant facet of an individual’s personality [5]. However, this population-based study highlights that personality traits were significant although marginally related to pain both in the female and the male group. Could it be that our findings can be explained by the ageing process? Nevertheless, a small but significant relationship to traits may help to predict different aspects of pain among older adults.

Some limitations should be mentioned. Fishbain et al. pointed out that certain trait tests and inventories may not be independent of pain state, as trait scores can change in line with pain treatment [31]. Despite the fact that adherence rates, such as adherence to medication, in women and men are very similar, some differences exist and women are slightly less adherent in following specific recommendations [32]. In this cross-sectional study it was not possible to predict changes in trait scores as a result of treatment. Another limitation is that the subjective experience of pain was self-reported and restricted to the four preceding weeks. The results do not reveal whether the reported pain was persistent or acute. However, the strength with the question is that it was used in other European studies of older adults [33]. The size of the sample can be discussed, but the strength of this population- based randomized study lies in the proportion of older people in the oldest old groups. As a goodness of fit of the models used, the Nagelkerke value was used. Nagelkerke value is higher, (10%), among women compared to men (5%). Even though R-squared is small it has information value. Since personality traits could be considered as a weak signal in the presence of a lot of other factors influencing the experience of pain even a weak signal could be informative. Since neuroticism is so clearly associated with other factors related to pain and the relationship is stronger among younger adults these results will raise two questions: (1) Do older people suffer from a different type of pain than younger adults? (2) Is more state like measures, i.e. pain catastrophizing stronger associated with personality traits among older adults?

Pain is common among older people and the majority suffers from insomnia [22, 26]. The gender-based differences in the elderly population are reinforced among those with pain [34, 35]. The youngest women in this study had marginally higher odds values for pain, which difference was statistically significant. This is in line with a previous study of QoL among older adults living with pain [33], but contrasts with findings by Rustøen et al. who compared older with middle-aged adults [34]. Our results demonstrate that insomnia has the strongest association with pain and the highest odds ratio. Traits were only marginally decreasing when adjusted for insomnia. Van de Laar et al. discussed whether personality factors play a causal role in the development of insomnia as they found a common trend among insomniacs to exhibit the trait of neuroticism [28].

Neither financial status nor educational level was found to have any relationship with pain among men. Educational level seems to be related to pain among older women. This is in contrast with findings from the MultiCare Cohort Study of patients aged 65 years and older where pain-related morbidity was equally distributed across age and socio-economic groups [35]. More studies are needed to investigate whether or not personality traits influence the incidence of pain and recovery rate from pain. Another interesting question is whether or not personality is a contributory factor to morbidity/mortality among individuals living with pain. Despite the fact that personality seems fairly stable across the lifespan, there is a lack of studies focusing on personality and its association with pain among older adults. Assessment of personality traits may be clinically important and contribute to a deeper understanding of how to manage older adults suffering from pain, thus contributing to diversity in successful ageing/longevity. However, since the relationship with personality traits is much weaker among older than younger adults, further studies are needed regarding if state like measures as pain catastrophizing, could be stronger associated with personality traits.

5 Conclusions

Neuroticism has a relationship with pain among elderly women. Neuroticism and openness have a relationship with pain among elderly men. Insomnia is associated with pain among both women and men. Thus the main result is a gender difference: pain has a stable relationship with neuroticism in both sexes, but also a relation with the personality trait openness among older men.

6 Implications

There is a need to increase awareness of the impact of personality as well as to provide improved treatment for pain and insomnia in older people.

Highlights

• Pain has a relationship with neuroticism among elderly women.

• In men, both neuroticism and openness are associated with pain.

• Both sexes suffer from insomnia.

• There is gender difference in the relationship between personality traits and pain.