HOME

Original Article

Korean J Pain 2018; 31(1): 16-26

Published online January 31, 2018 https://doi.org/10.3344/kjp.2018.31.1.16

Copyright © The Korean Pain Society.

Neuroticism and pain catastrophizing aggravate response to pain in healthy adults: an experimental study

Adriana Banozic1*, Ana Miljkovic2, Marijana Bras3, Livia Puljak1, Ivana Kolcic2, Caroline Hayward4, and Ozren Polasek2

1Laboratory for Pain Research, University of Split, School of Medicine, Split, Croatia.

2Department of Public Health, University of Split School of Medicine, Split, Croatia.

3Centre for Palliative Medicine, Medical Ethics and Communication Skills (CEPAMET), School of Medicine, University of Zagreb, Zagreb, Croatia.

4Institute for Genomics and Molecular Medicine, University of Edinburgh, Edinburgh, UK.

Correspondence to: Adriana Banozic. Laboratory for Pain Research, University of Split, School of Medicine, Connexis Tower, 1 Fusionopolis Way, Connexis Tower, Singapore 138632 Fusionopolis Pl, 138632 Singapore. Tel: +65-64196506, Fax: +65-6463-0200, adriana_banozic@ihpc.a-star.edu.sg

Received: July 25, 2017; Revised: October 5, 2017; Accepted: November 15, 2017

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Background

The aim of this study was to investigate the association between neuroticism, pain catastrophizing, and experimentally induced pain threshold and pain tolerance in a healthy adult sample from two regions of the country of Croatia: the island of Korcula and city of Split.

Methods

A total of 1,322 participants were enrolled from the Island of Korcula (n = 824) and the city of Split (n = 498). Participants completed a self-reported personality measure Eysenck Personality Questionnaire (EPQ) and pain catastrophizing questionnaire Pain Catastrophizing Scale (PCS), followed by a mechanical pain pressure threshold and tolerance test. We have explored the mediating role of catastrophizing in the relationship between neuroticism and pain intensity.

Results

The results showed that pain catastrophizing partially mediated the relationship between neuroticism and pain intensity, suggesting the importance of pain catastrophizing in increasing vulnerability to pain. The results also indicated gender-related differences, marked by the higher pain threshold and tolerance in men.

Conclusions

This study adds to the understanding of the complex interplay between personality and pain, by providing a better understanding of such mechanisms in healthy adults.

Keywords: Catastrophization, Gender differences Human Trafficking, Neuroticism, Pain catastrophizing, Pain measurement, Pain threshold, Patient health questionnaire

An individual's pain experience is multidimensional and dynamic, comprising psychological, cognitive, physiological and behavioral determinants [1]. Among these, personality is one of the most extensively investigated psychological constructs [2,3,4,5].

Previous research has suggested that baseline personality traits significantly contribute to pain heterogeneity, as well as pain-related characteristics [6,7,8]. In general, neuroticism, has often been linked with negative health outcomes [9,10,11].

Neuroticism was a significant predictor of fibromyalgia symptoms along with factors associated with the hypothalamic-pituitary-adrenal axis in a study that compared 22 fibromyalgia patients to 17 controls [12].

Affleck et al. [13] showed that rheumatoid arthritis patients who reported higher in neuroticism reported more intense pain and a more negative mood, their daily mood was less strongly linked to their daily pain.

The most robust finding was a significant phenotypic association between cold pressor pain intensity and the personality facets Impulsiveness (a facet of Neuroticism) and Excitement-Seeking (a facet of Extraversion), and estimates of the genetic correlation were 0.37 (P < 0.05) and 0.43 (P < 0.05), respectively [14].

Neuroticism is nowadays considered to be a broad construct and some pain-related cognitive and behavioral characteristics, including pain catastrophizing, are shown to be associated to it [15,16]. Furthermore, catastrophizing has been shown to mediate the relationship between negative affect (neuroticism), somatic complaints, and functional disability [17,18] and its consistent association with pain has been observed across a variety of measures and patient groups, where it accounts for 7 to 31% of the variance in pain ratings [19].

The association of the remaining two dimensions of EPQ to pain, extraversion and psychoticism, are less consistent. It has been shown that participants who scored higher on the extraversion scale tolerated pain longer [14]. A study by Harkins explored the associations of neuroticism and extraversion with experimental thermal pain (43-51C stimuli) and clinical pain in patients with myofascial pain dysfunction. Extroverts didn't differ from introverts in visual analogue scale pain ratings from thermal pain nor VAS ratings of their clinical pain. Psychoticism, as the third segment of Eysencks' personality model which consists of a combination of obsessive, compulsive and paranoid sub-traits was only occasionally found to influence chronic pain treatment outcomes [20].

Lee et al. [21] 2010 demonstrated the results of a regression analysis which showed that lower-order pain constructs (fear, catastrophizing, and hypochondriasis) are correlated through a single underlying factor that is partially related to the higher-order negative-valence personality traits; 2) pain-was more strongly predictive of pain quality than higher order traits (e.g. neuroticism); and 3) qualitative pain ratings rather than quantitative ones were significantly predicted by psychological factors.

Even though there are numerous studies exploring the association between personality traits and chronic pain conditions [22,23,24,25], it is often difficult to determine whether an individual's personality characteristics contribute to how they perceive and experience pain or, conversely, whether it is their pain condition that has affected their personality. Accordingly, the current study examined the above constructs in two ostensibly healthy participant samples, using standardized measurements for both pain and personality constructs.

Participants were derived from an island and a mainland setting in the Croatian region, respectively, whereas previous studies have suggested high levels of social, environmental and genetic homogeneity [26,27,28]. The current study aimed to examine the relationship between higher-order personality traits (neuroticism, extraversion, psychoticism) and pain catastrophizing as well as their relation to experimentally-induced pressure pain, by testing whether pain catastrophizing mediates the relationship between neuroticism and pain. These relationships would be explored on the level of a complete sample as well as island (Korcula) and mainland (Split) subsamples. We hypothesized that neuroticism and psychoticism would be correlated to pain catastrophizing while extraversion would not. Based on previous research, we also hypothesized that pain catastrophizing would at least partially mediate the relationship between neuroticism/psychoticism and pain responses.

1. Ethics statement

The experiment was conducted in accordance with the Helsinki Guidelines and IASP guidelines for human pain research. Approval was granted by the Ethics Committee of the School of Medicine, University of Split. All participants have provided written informed consent which was also previously approved by the ethics committee.

2. Participants and study setting

For purposes of this study, we enrolled participants from the island of Korcula and the mainland city of Split. All the participants were apparently healthy, with no noticeable severe medical conditions that could affect their health status.

A trained research assistant evaluated if they had any of the following exclusion criteria, which could preclude understanding of study procedures or participation in pain induction procedures: acute illness or injury that may impact their performance (eg. fever, flu symptoms), hand injuries, use of opioids in the previous 48 hours, prescription medication, developmental delay, or significant anatomic impairment.

3. Measures

Pressure pain threshold (PPT) is defined as the amount of force needed to elicit a sensation of pain distinct from pressure. In this study, PPT was measured using a handheld digital pressure algometer (Wagner Instruments, Greenwich, CT), mounted with a 1-cm diameter circular probe and calibrated in kilopascals (kPa). To assess the PPT, the probe was held perpendicularly on the middle phalanx of the index finger of both hands, and the pressure was applied at an approximately constant rate of 5 kPa/s. When the PPT was reached, the participant said “stop”, at which moment the algometer pressure was lifted, while the device recorded the maximum force achieved. In order to provide reliable measurement, a total of five measurements were made. The initial two measurements were done to familiarize the participants with the process. After at least 30 minutes, the PPT was measured again, three times at the same spot. Finally, we calculated mean value for all three measurements to obtain mean PPT.

The pressure pain tolerance (PPTOL) was measured in the similar way as the PPT, but this time the participants were asked to tolerate the pain for as long as it seemed reasonable. We also set a cut-off value at 130 kPa in order to avoid tissue damage in participants who still did not stop the pressure application. Two consecutive measurements were done, and their mean value was used as the PPTOL, for each hand separately. Participants were then involved in the pain pressure test in the following order: PPT and then PPTOL. The same team of experimenters conducted all procedures, with a female researcher who performed all of the pain pressure tolerance and threshold measurements for participants.

The Eysenck Personality Questionnaire-Revised (EPQ-R) was used to provide estimates in four sub-scales: psychoticism, extraversion, neuroticism, and social desirability (applied only as a control scale and not analyzed in this study). Higher scores on the neuroticism scale (EPQ-N) indicate an anxious, worrisome, overly emotional, and somewhat rigid personality. A higher score on the extraversion scale (EPQ-E) indicates a sociable, optimistic, excitement-craving, easy-going personality. Higher scores on the psychoticism scale (EPQ-P) indicate a disinhibited, hostile, and non-conformist personality. EPQ-R has been demonstrated to have good internal consistency and test-retest reliability [29]. In this study we used a short form of the EPQ-R with 48 items, containing 12 items for each of the subscales. The Croatian version of this questionnaire has been validated and extensively used [30].

The Pain Catastrophizing Scale (PCS) was used as a measure of catastrophic thinking associated with pain [31]. The PCS instructions require a participant to reflect on past painful experiences, and to indicate the degree to which they experienced each of 13 thoughts or feelings when experiencing pain, on 5-point scales with the end points (0) not at all and (4) all the time. The PCS yields a total score and three subscale scores assessing rumination, magnification, and helplessness. The validated Croatian version of the PCS was used. PCS measurements in this study were shown to have very high internal consistencies (Cronbach coefficient αs: total PCS = 0.94, rumination = 0.89, magnification = 0.80, and helplessness = 0.88).

4. Statistics

Descriptive statistics were calculated for each study variable, including distinctive analysis for the two cohorts (Korcula and Split), as well as the gender differences. Variance homogeneity analysis would be conducted first which would determine how the further statistical analysis would proceed (entire sample analysis or separate analysis for each cohort).

To determine if sample distributions were approximately normal, the Kolmogorov-Smirnov test was used. The General Linear Model (GLM), including the factors of Group and Sex on the EPQ personality and pain ratings, with the age as the covariate was used to explore the differences between the island and mainland cohorts.

Univariate comparisons for sociodemographic characteristics were performed using appropriate tests (the t-test or Chi square test). Associations of the pain and psychological variables were assessed using Pearson's correlation coefficients. In addition, a regression analysis was used to test mediation models of pain catastrophizing, EPQ traits, and outcomes in perceived pain (pain tolerance/threshold) using the criteria outlined by Baron and Kenny [32] are: (1) (neuroticism) must be significantly associated with (the pain threshold and pain tolerance); (2) (neuroticism) must be significantly associated with the mediator (catastrophizing); (3) the mediator (catastrophizing) must be significantly associated with (the pain tolerance and pain threshold) after controlling for the (neuroticism); and (4) the strength of the relationship between (the neuroticism) and (the pain threshold and pain tolerance) must be significantly reduced after controlling for the mediator (pain catastrophizing scale, Appendix 1).

All analyses were conducted using IBM SPSS for Windows Version 17 (SPSS Inc., Chicago, IL). The significance of indirect paths was computed by Process (SPSS macro) [33]. Significance was set at the level of P < 0.05.

A total of 1,322 participants were enrolled in this study, with 824 from Korcula and 498 participants from Split (Table 1). Personality trait scores slightly differed between the Split and Korcula cohorts, so we presented the EPQ and pain reports separately. The initial comparison suggested that the cohorts differed in age which was then added as a covariate in further analysis. The Korcula cohort had significantly higher values of psychoticism, and marginally lower mean values of extraversion and neuroticism, compared to Split cohort (Table 1). Pain catastrophizing scores were significantly higher for the Korcula cohort compared to the Split cohort.

Furthermore, a cohort-based analysis suggested that in both instances women had higher neuroticism scores, did not differ on the extraversion scale, while in terms of psychoticism the results suggested either significant difference in Split or marginally insignificant difference in Korcula (Table 2).

Neuroticism was the only personality trait that indicated gender differences, as women showed significantly higher results (F = 26.24, P < 0.001) when controlled for age; however, no differences were found between the two cohorts. The island cohort showed increased pain catastrophizing scores (F = 51.50, P < 0.001) and increased psychoticism (F = 28.23, P < 0.001). No significant interaction effect was found between the cohort and the gender of the person for any of the personality constructs (lowest P = 0.301).

The association between neuroticism and pain threshold was mediated by pain catastrophizing (Fig. 1), the same pattern being found in both cohorts (Korcula and Split). The standardized regression coefficient between pain threshold and neuroticism decreased when controlling for pain catastrophizing. The other conditions of mediation were also met: neuroticism was a significant predictor in pain perception and pain catastrophizing, while pain catastrophizing was a significant predictor in pain perception, while controlling for neuroticism (Fig. 1).

The comparison of PPT and PPTOL measures for both hands, adjusted for age, suggested that cohorts significantly differed in their response to pain (Table 3). PPT was higher for the mainland cohort (F = 102.32, P < 0.0011), similarly to PPTOL, (F = 9.52, P = 0.002). Gender differences were observed across all measures in both cohorts, where men consistently reported higher thresholds (F = 49.88, P < 0.001) as well as higher tolerance (F = 90.38, P < 0.001), even after adjustment for age.

There was no significant interaction effect between the cohort and the gender of the person on pain tolerance measures (P > 0.05). This indicates that affiliation to either cohort affected pain tolerance measurement of both genders in the same way.

Correlations between pain threshold and tolerances were significant for all pairs at the level of P < 0.001 (Table 4).

Contrary to our expectations, the higher-order, negative valence traits (neuroticism and psychoticism) were not correlated with each other (Table 4). Psychoticism was not correlated with any of the traits (Table 4). Extraversion was negatively correlated with negative valence traits. The lower order construct, pain catastrophizing, had the highest correlation with neuroticism and was significantly correlated with other higher order traits (Table 4).

The results of this study show a strong association of neuroticism with pain catastrophizing, and a partial mediation effect of pain catastrophizing in the association between pain and neuroticism. The remaining two personality constructs were not consistently related to pain (either pain tolerance or pain threshold). Although pain catastrophizing was significantly associated to all measured personality traits in bivariate analysis, only marginal associations were found with the pain reports.

Neuroticism as a higher order personality trait proved to be directly associated with pain reports and pain catastrophizing (a lower order personality trait) served as a partial mediator to this association, contrary to the recent literature [34,35,36,37,38].

Our results support the idea that neuroticism could be perceived as a vulnerability factor within a diathesis-stress framework [15]. When a person is faced with a stressor, such as (acute) pain, neuroticism may influence whether the person appraises the pain as threatening or not [36,39,40]. No direct effect of catastrophizing could also be a consequence of contextual factors such as the threat value of pain, which may differ in laboratory settings versus clinical environments.

Some studies have suggested that measuring pain catastrophizing in an experimental setting could be seen as more valid if taken after noxious stimulation [41]. Post-noxious assessment of catastrophizing refers to a participant's actual behavior in response to an immediate and relevant pain situation. This finding is directly applicable to the clinicians' assessment of catastrophizing in the chronic pain patient [39].

In addition, neuroticism may even reduce the threshold at which pain is perceived as threatening, and at which pain elicits catastrophic thoughts. These results support a dynamic view of personality where behaviors are modified according to the context. Extraversion and psychoticism explored in our study did not seem to play a role in pain perception. We found no evidence that participants who scored higher on the extraversion scale were able to tolerate more pain compared to introverts as is suggested in the literature [42].

Pain catastrophizing, as assessed in this study, did not have any direct association to pain tolerance, contrary to the growing body of literature that suggests pain catastrophizing to be a stable mode of responding to painful experiences [43,44,45]. No cohort-related or gender-related differences were statistically significant, even though women and the island cohort had elevated results on the PCS.

Neuroticism is also characterized by emotional instability, sensitivity, and dependency which may serve as predisposition for pain stimulus appraisal or threat of a potential pain stimulus [46]. Also neuroticism was the only psychological variable that differentiated between men and women. In general, women tend to score higher on neuroticism [46,47], whereas gender differences in other Eysenck personality traits have been either inconsistent or of negligible magnitude.

The described gender differences seem to be consistent across different ages in the life span [48]. Several authors have indicated that gender differences in personality are modest in magnitude but consistent with gender stereotypes, and replicable cross-culturally [14]. A systematic review published in 2012, which examined gender differences in experimentally induced pain, showed that women and men have comparable thresholds for cold and ischemic pain, while pressure pain thresholds were lower in women compared to men [49]. They indicated that women tolerate less thermal (heat, cold) and pressure pain than men. The majority of the studies that measured pain intensity and unpleasantness showed no sex difference in many pain modalities [50,51,52]. A considerable body of experimental research showed a lack of consistency related to gender differences in human pain sensitivity, even with the use of deep, tonic, long-lasting stimuli, which are known to better mimic clinical pain [53].

Island-mainland differences were evident in both the pressure pain threshold and pressure pain tolerance measures. Also, pain catastrophizing and psychoticism seem to be the only personality traits which produced a consistent difference between these two cohorts. The study of isolated populations is advantageous because of its increased genetic and environmental homogeneity compared with urban populations [27]. Even though studying island populations facilitates gene mapping, it has the disadvantage of reducing the diversity of genetic effects and increasing the extent of shared environmental effects [26].

The limitations of this study include selection bias (the inability to properly address the sample representativeness for the cohort they are representing) and the facts that all pain ratings were performed by a female research assistant, which could have potentially affected the results (pain reports) of men. Furthermore, some results were shown to be inconsistent with previously published studies, thus suggesting that replication of the results is needed before more general conclusions can be drawn. Nevertheless, these findings could have important practical implications, as certain factors assessed a priori (e.g. preoperatively) may have predictive value for those who will perceive greater pain using qualitative assessments.

A better understanding of the structure defined by potential pain-related psychological variables and their influence on the perception of acute pain may assist in the development of future treatment. Individualized multidisciplinary therapeutic interventions may be plausible to better meet the needs of patients for a variety of acute pain conditions.

Pain Catastrophizing Scale (English version, Copyright 1995, 2001, 2004, 2006, 2009 Michael JL Sullivan, PhD)

figure


Sociodemographic Information and Basic Descriptors of the Two Investigated Cohorts




Summary Statistics for Psychological Variables (Mean ± SD), by Gender and Cohort



PCS: pain catastrophizing scale, EPQ-P: psychoticism, EPQ-E: extraversion, EPQ-N: neuroticism.


Summary Statistics for Pain Variables (Mean ± SD), by Gender and Cohort



PPTOL-R: pressure pain tolerance (right hand), PPT-R: pressure pain threshold (right hand).


Pearson's Correlation Coefficients between Pain Measures and Personality Constructs. Correlation Coefficients are Provided above the Diagonal, P values Below



PPTOL-R: pressure pain tolerance (right hand), PPT-R: pressure pain threshold (right hand), PCS: pain catastrophizing, EPQ-P: psychoticism, EPQ-E: extraversion, EPQ-N: neuroticism.

  1. Ebert MH, Kerns RD. Behavioral and psychopharmacologic pain management. Cambridge: Cambridge University Press; 2010. p. 506.
  2. al Absi, M, Rokke, PD. Can anxiety help us tolerate pain?. Pain, 1991;46;43-51.
    Pubmed
  3. Garron, DC, Leavitt, F. Psychological and social correlates of the back pain classification scale. J Pers Assess, 1983;47;60-65.
    Pubmed
  4. Jones, A, Spindler, H, Jørgensen, MM, Zachariae, R. The effect of situation-evoked anxiety and gender on pain report using the cold pressor test. Scand J Psychol, 2002;43;307-313.
    Pubmed
  5. Tang, J, Gibson, SJ. A psychophysical evaluation of the relationship between trait anxiety, pain perception, and induced state anxiety. J Pain, 2005;6;612-619.
    Pubmed
  6. Gatchel, RJ. Comorbidity of chronic pain and mental health disorders: the biopsychosocial perspective. Am Psychol, 2004;59;795-805.
    Pubmed
  7. Marbach, JJ, Raphael, KG. Phantom tooth pain: a new look at an old dilemma. Pain Med, 2000;1;68-77.
    Pubmed
  8. Wade, JB, Dougherty, LM, Hart, RP, Rafii, A, Price, DD. A canonical correlation analysis of the influence of neuroticism and extraversion on chronic pain, suffering, and pain behavior. Pain, 1992;51;67-73.
    Pubmed
  9. Lahey, BB. Public health significance of neuroticism. Am Psychol, 2009;64;241-256.
    Pubmed
  10. Smith, TW, MacKenzie, J. Personality and risk of physical illness. Annu Rev Clin Psychol, 2006;2;435-467.
    Pubmed
  11. Payne, LA, Seidman, LC, Lung, KC, Zeltzer, LK, Tsao, JC. Relationship of neuroticism and laboratory pain in healthy children: does anxiety sensitivity play a role?. Pain, 2013;154;103-109.
    Pubmed
  12. Malt, EA, Olafsson, S, Lund, A, Ursin, H. Factors explaining variance in perceived pain in women with fibromyalgia. BMC Musculoskelet Disord, 2002;3;12.
    Pubmed
  13. Affleck, G, Tennen, H, Urrows, S, Higgins, P. Neuroticism and the pain-mood relation in rheumatoid arthritis: insights from a prospective daily study. J Consult Clin Psychol, 1992;60;119-126.
    Pubmed
  14. Vassend, O, Røysamb, E, Nielsen, CS. Five-factor personality traits and pain sensitivity: a twin study. Pain, 2013;154;722-728.
    Pubmed
  15. Goubert, L, Crombez, G, Van Damme, S. The role of neuroticism, pain catastrophizing and pain-related fear in vigilance to pain: a structural equations approach. Pain, 2004;107;234-241.
    Pubmed
  16. Kadimpati, S, Zale, EL, Hooten, MW, Ditre, JW, Warner, DO. Associations between neuroticism and depression in relation to catastrophizing and pain-related anxiety in chronic pain patients. PLoS One.
    Pubmed
  17. Vervoort, T, Goubert, L, Eccleston, C, Bijttebier, P, Crombez, G. Catastrophic thinking about pain is independently associated with pain severity, disability, and somatic complaints in school children and children with chronic pain. J Pediatr Psychol, 2006;31;674-683.
    Pubmed
  18. Swinkels-Meewisse, IE, Roelofs, J, Verbeek, AL, Oostendorp, RA, Vlaeyen, JW. Fear-avoidance beliefs, disability, and participation in workers and non-workers with acute low back pain. Clin J Pain, 2006;22;45-54.
    Pubmed
  19. Sullivan, MJ, Thorn, B, Haythornthwaite, JA, Keefe, F, Martin, M, Bradley, LA, et al. Theoretical perspectives on the relation between catastrophizing and pain. Clin J Pain, 2001;17;52-64.
    Pubmed
  20. Vendrig, AA, Hoofs, MH, van Akkerveeken, PF, Lamberts-Hopkes, KJ. Multidisplinary approach to chronic back pain: postrehabilitation resumption of work the same 3–4 years later as after 6 months. Ned Tijdschr Geneeskd, 2000;144;2207-2209.
    Pubmed
  21. Lee, JE, Watson, D, Frey Law, LA. Lower-order pain-related constructs are more predictive of cold pressor pain ratings than higher-order personality traits. J Pain, 2010;11;681-691.
    Pubmed
  22. Geisser, ME, Haig, AJ, Wallbom, AS, Wiggert, EA. Pain-related fear, lumbar flexion, and dynamic EMG among persons with chronic musculoskeletal low back pain. Clin J Pain, 2004;20;61-69.
    Pubmed
  23. Rollman GB. In: Melzack R. Pain measurement and assessment. New York (NY): Raven Press; 1983. p. 251-258.
  24. Zisk, RY, Grey, M, MacLaren, JE, Kain, ZN. Exploring sociodemographic and personality characteristic predictors of parental pain perceptions. Anesth Analg, 2007;104;790-798.
    Pubmed
  25. Thorn, BE, Ward, LC, Sullivan, MJ, Boothby, JL. Communal coping model of catastrophizing: conceptual model building. Pain, 2003;106;1-2.
    Pubmed
  26. Miljković, A, Pehlić, M, Budimir, D, Gunjača, G, Mudnić, I, Pavić, A, et al. Can genetics aggravate the health of isolated and remote populations? The case of gout, hyperuricaemia and osteoarthritis in Dalmatia. Rural Remote Health, 2013;13;2153.
    Pubmed
  27. Vitart, V, Biloglav, Z, Hayward, C, Janicijevic, B, Smolej-Narancic, N, Barac, L, et al. 3000 years of solitude: extreme differentiation in the island isolates of Dalmatia, Croatia. Eur J Hum Genet, 2006;14;478-487.
    Pubmed
  28. Polasek, O, Kolcić, I, Smoljanović, A, Stojanović, D, Grgić, M, Ebling, B, et al. Demonstrating reduced environmental and genetic diversity in human isolates by analysis of blood lipid levels. Croat Med J, 2006;47;649-655.
    Pubmed
  29. Eysenck HJ, Eysenck SB. Manual of the Eysenck personality questionnaire: (EPQ-R Adult). San Diego (CA): Educational and Industrial Testing Service.
  30. Eysenck HJ, Eysenck SB. Priručnik za Eysenckov upitnik ličnosti EPQ (djeca i odrasli). Jastrebarsko: Naklada Slap.
  31. Sullivan, MJ, Bishop, SR, Pivik, J. The pain catastrophizing scale: development and validation. Psychol Assess, 1995;7;524-532.
  32. Baron, RM, Kenny, DA. The moderator-mediator variable distinction in social psychological research: conceptual, strategic, and statistical considerations. J Pers Soc Psychol, 1986;51;1173-1182.
    Pubmed
  33. Hayes AF. Introduction to mediation, moderation, and conditional process analysis: a regression-based approach. New York (NY): Guilford Press.
  34. France, CR, France, JL, al'Absi, M, Ring, C, McIntyre, D. Catastrophizing is related to pain ratings, but not nociceptive flexion reflex threshold. Pain, 2002;99;459-463.
    Pubmed
  35. Rhudy, JL, Martin, SL, Terry, EL, France, CR, Bartley, EJ, DelVentura, JL, et al. Pain catastrophizing is related to temporal summation of pain but not temporal summation of the nociceptive flexion reflex. Pain, 2011;152;794-801.
    Pubmed
  36. Wee, LE, Sin, D, Cher, WQ, Li, ZC, Tsang, T, Shibli, S, et al. “I'm healthy, I don't have pain”- health screening participation and its association with chronic pain in a low socioeconomic status Singaporean population. Korean J Pain, 2017;30;34-43.
    Pubmed
  37. Ghobadifar, MA. An update on the management of diabetic neuropathic pain: a few comments. Korean J Pain, 2015;28;158-159.
    Pubmed
  38. Komasi, S, Soroush, A, Bahremand, M, Saeidi, M. Irrational beliefs predict pain/discomfort and emotional distress as a result of pain in patients with non-cardiac chest pain. Korean J Pain, 2016;29;277-279.
    Pubmed
  39. Thorn, BE, Clements, KL, Ward, LC, Dixon, KE, Kersh, BC, Boothby, JL, et al. Personality factors in the explanation of sex differences in pain catastrophizing and response to experimental pain. Clin J Pain, 2004;20;275-282.
    Pubmed
  40. Sullivan, MJ, Martel, MO, Tripp, DA, Savard, A, Crombez, G. Catastrophic thinking and heightened perception of pain in others. Pain, 2006;123;37-44.
    Pubmed
  41. Osborn, J, Derbyshire, SW. Pain sensation evoked by observing injury in others. Pain, 2010;148;268-274.
    Pubmed
  42. Ferracuti, S, De Carolis, A. Relationships among Eysenck's extraversion, Rorschach's Erlebnistypus, and tolerance of experimental tonic pain (Cold Water Pressor Test). Percept Mot Skills, 2005;100;237-248.
    Pubmed
  43. Burns, JW, Glenn, B, Bruehl, S, Harden, RN, Lofland, K. Cognitive factors influence outcome following multidisciplinary chronic pain treatment: a replication and extension of a cross-lagged panel analysis. Behav Res Ther, 2003;41;1163-1182.
    Pubmed
  44. Campbell, CM, Kronfli, T, Buenaver, LF, Smith, MT, Berna, C, Haythornthwaite, JA, et al. Situational versus dispositional measurement of catastrophizing: associations with pain responses in multiple samples. J Pain, 2010;11;443-453.e2.
    Pubmed
  45. Kunz, M, Chatelle, C, Lautenbacher, S, Rainville, P. The relation between catastrophizing and facial responsiveness to pain. Pain, 2008;140;127-134.
    Pubmed
  46. Lehmann, R, Denissen, JJ, Allemand, M, Penke, L. Age and gender differences in motivational manifestations of the Big Five from age 16 to 60. Dev Psychol, 2013;49;365-383.
    Pubmed
  47. Lynn, J, Teno, JM, Phillips, RS, Wu, AW, Desbiens, N, Harrold, J, et al. Perceptions by family members of the dying experience of older and seriously ill patients. Ann Intern Med, 1997;126;97-106.
    Pubmed
  48. Chapman, BP, Duberstein, PR, Sörensen, S, Lyness, JM. Gender differences in five factor model personality traits in an elderly cohort: extension of robust and surprising findings to an older generation. Pers Individ Dif, 2007;43;1594-1603.
    Pubmed
  49. Dixon, KE, Thorn, BE, Ward, LC. An evaluation of sex differences in psychological and physiological responses to experimentally-induced pain: a path analytic description. Pain, 2004;112;188-196.
    Pubmed
  50. Mogil, JS. Sex differences in pain and pain inhibition: multiple explanations of a controversial phenomenon. Nat Rev Neurosci, 2012;13;859-866.
    Pubmed
  51. Mogil, JS, Bailey, AL. Sex and gender differences in pain and analgesia. Prog Brain Res, 2010;186;141-157.
    Pubmed
  52. Mogil, JS, Chesler, EJ, Wilson, SG, Juraska, JM, Sternberg, WF. Sex differences in thermal nociception and morphine antinociception in rodents depend on genotype. Neurosci Biobehav Rev, 2000;24;375-389.
    Pubmed
  53. Racine, M, Tousignant-Laflamme, Y, Kloda, LA, Dion, D, Dupuis, G, Choinière, M. A systematic literature review of 10 years of research on sex/gender and pain perception - part 2: do biopsychosocial factors alter pain sensitivity differently in women and men?. Pain, 2012;153;619-635.
    Pubmed