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. 2019 May 3;98(18):e15345. doi: 10.1097/MD.0000000000015345

Relationships among stress, emotional intelligence, cognitive intelligence, and cytokines

Ye-Ha Jung a, Na Young Shin b, Joon Hwan Jang a,c, Won Joon Lee d, Dasom Lee a, Yoobin Choi a, Soo-Hee Choi a,e,∗, Do-Hyung Kang f,∗
Editor: Massimo Tusconi
PMCID: PMC6504531  PMID: 31045776

Supplemental Digital Content is available in the text

Keywords: cytokines, emotional intelligence, intelligence quotient, hemispheric dominance, functional connection, stress

Abstract

The brain has multiple functions, and its structures are very closely related to one another. Thus, the brain areas associated with stress, emotion, and intelligence are closely connected. The purpose of this study was to investigate the multiple associations between stress and emotional intelligence (EI), between EI and intelligence quotient (IQ), between cytokines and stress, and between cytokines and IQ. We measured the stress, EI, cognitive intelligence using IQ, and cytokine levels of 70 healthy subjects. We also analyzed the association of cytokines with IQ according to hemispheric dominance using the brain preference indicator (BPI). We found significant negative correlations between stress and the components of EI, such as emotional awareness and expression, emotional thinking, and emotional regulation. High levels of anger, which is a component of stress, were significantly related to poor emotional regulation. Additionally, emotional application was positively correlated with full-scale IQ scores and scores on the vocabulary, picture arrangement, and block design subtests of the IQ test. High IL-10 levels were significantly associated with low stress levels only in the right-brain-dominant group. High IL-10 and IFN-gamma levels have been associated with high scores of arithmetic intelligence. TNF-alpha and IL-6 were negatively associated with vocabulary scores and full-scale IQ, but IL-10 and IFN-gamma were positively associated with scores on the arithmetic subtest in left-brain-dominant subjects. On the other hand, IL-10 showed positive correlations with scores for vocabulary and for vocabulary and arithmetic in right-brain-dominant subjects. Furthermore, we found significant linear regression models which can show integrative associations and contribution on emotional and cognitive intelligence. Thus, we demonstrated that cytokines, stress, and emotional and cognitive intelligence are closely connected one another related to brain structure and functions. Also, the pro-inflammatory cytokines TNF-alpha and IL-6 had negative effects, whereas the anti-inflammatory cytokines (e.g., IL-10 and IFN-gamma) showed beneficial effects, on stress levels, and multiple dimensions of emotional and cognitive intelligence. Additionally, these relationships among cytokines, stress, and emotional and cognitive intelligence differed depending on right and left hemispheric dominance.

1. Introduction

Stress can be defined as a real or anticipated disruption of homeostasis or an anticipated threat to well-being.[1] It has been established that psychosocial stressors are related to disease development, and psychosocial interventions have proven useful for treating stress-related disorders and may influence the course of chronic diseases.[2] Emotional intelligence (EI) plays a role as a moderator of the relationship between stress and psychological health,[3] as it promotes the adoption of proactive and effective coping strategies when dealing with stress.[4] EI is the ability of individuals to recognize their own and others’ emotions, to use emotional information to guide their thinking and behavior, and to discriminate among different feelings and label them appropriately.[5] Higher EI is significantly related to lower stress and burnout,[6,7] and EI influences stress levels, ability to perform tasks, and effectiveness when working with others.[8] The relationship between cognitive impairment and stress-related exhaustion has been established,[9] and process-based cognitive training has been provided to patients with stress-related exhaustion.[10] Intelligence quotient (IQ) and EI are essential to human cognitive control processes.[11] Although, stress, emotional intelligence, and cognitive intelligence were closely connected, complex relationships among them have little known in these area. Thus, we focused on the dynamic associations between stress and EI, between EI and IQ and between stress and IQ in the same subjects at the same time.

In addition, cytokines are important in health and disease, specifically immune responses, inflammation, trauma, cancer and, etc.[12–14] On the other hand, immune reactions of neuronal bodies and glial cells are also implicated in the survival and conditioning of neurons to regenerate severed nerves, showing the role of inflammation and cytokines in peripheral nerve regeneration.[15] In addition, some of the cognitive deficits associated with inflammation may in part be related to inflammation-induced reductions in adult hippocampal neurogenesis, indicating that immune-reactive cells in the brain can support or disrupt neural processes depending on the phenotype and behavior of the cells in cognition and behavior.[16] Peripheral inflammatory responses can affect the brain, as neuroinflammation contributes to the increase in neurotoxic kynurenine pathway metabolites, and pro-inflammatory cytokines can also exert direct neurotoxic effects on specific brain regions.[17] The frontal brain regions involved in cognition and affect appear to be selectively affected by exposure to community violence, which has been associated with lower IQ scores.[18] Therefore, considering that cognitive functions or cognitive deficits associated with inflammation may be associated with some cytokines, we investigated the relationships between cytokines and cognitive intelligence in this study. Furthermore, stress is related to the hypothalamo–pituitary–adrenocortical (HPA) axis and inflammatory reactivity,[19,20] and many pro-inflammatory cytokines have a markedly activating influence on the HPA axis.[21] IL-6 and IL-1β have been associated with stress,[22] and restraint stress significantly decreased IFN-γ production in rats.[23] Thus, we also focused on the relationships between stress-related cytokines and cognitive intelligence.

The effects of hemispheric lateralization on affective responses, emotion, language, and dexterity have been well established.[24] Indeed, structural laterality is associated with cognition and mood,[25] and the hemispheric lateralization of certain cognitive abilities in the human brain is beneficial for functioning.[26] The central nervous system plays a crucial role in the body's stress-related mechanisms, and stress may induce abnormalities in the sympathetic nervous system and HPA axis. Emotion is related to a group of structures at the center of the brain known as the limbic system, which includes the hypothalamus, cingulate cortex, hippocampi, and other structures. And, both IQ and EI are related to human cognitive control processes.[11] Thus, stress, emotion, and intelligence are structurally and functionally closely related to one another.

Therefore, we investigated associations among stress, EI, and IQ and then examined correlations between cytokines and these variables, suggesting hypothetical interactions among them (Supplementary Figure 1). Additionally, we investigated these relationships according to hemispheric dominance.

2. Method

2.1. Subjects

We measured the stress, EI, IQ, and cytokine levels of 70 healthy subjects. Five subjects had no answer in most of items in Stress Response Inventory (SRI) and one subject in Brain Preference Indicator (BPI). So we analyzed with 65 subjects except 5 subjects in related data. The Structured Clinical Interview for DSM-IV-nonpatient version was used to assess psychiatric disorders. Exclusion criteria included history of psychosis, bipolar disorder, major depressive disorder, substance abuse or dependence, significant head injury, seizure disorder, or mental retardation. This study was approved by the Institutional Review Board of Seoul National University Hospital, and informed consent was obtained from all participants.

2.2. Stress Response Inventory (SRI)

This experiment used 22 questions derived from the original SRI questionnaire.[27] Each question was scored on a Likert-type scale including “not at all” (0), “somewhat” (1), “moderately” (2), “very much” (3), or “absolutely” (4). The 22 questions were categorized into 3 simplified stress factors: somatization, depression, and anger.[28]

2.3. Emotional intelligence (EI)

EI was measured using the Korean version of the instrument[29] developed based on the ability model of EI.[30] EI was measured with 50 questions categorized into 5 simplified factors of emotional awareness and expression, empathy, emotional thinking, emotional application, and emotional regulation. Each of these 5 simplified factors consisted of 10 questions describing different feelings and emotions. Each question was scored on a 5-point Likert-scale of “not at all” (1), “somewhat” (2), “moderately” (3), “very much” (4), or “absolutely” (5). Each factor was scored, and higher scores indicated greater EI.

2.4. Intelligence quotient (IQ)

We used an abbreviated form of the Korean version of the Wechsler Adult Intelligence Scale[31] consisting of the vocabulary, arithmetic, block design, and picture arrangement subtests to estimate the full-scale IQ.[32] We adopted the abbreviated form to decrease participants’ cognitive fatigue and improve their cooperativeness. In addition to the above 4 scales, digit span was also administered to measure verbal working memory.

2.5. Cytokine assays

TNF-alpha and IL-6 (R&D Systems, Minneapolis, MN) and IFN-gamma and IL-10 (Pierce Endogen, Rockford, IL) levels were measured using enzyme-linked immunosorbent assay (ELISA) kits. Absorbance was measured at 450 nm in a microplate reader (Versamax; Molecular Devices, Sunnyvale, CA). All plasma samples were coded so that investigators could perform the assay under blind conditions. All measurements were run in triplicate, and the statistical analysis relied on the average values obtained after subtracting the average of the blanks.

2.6. Brain preference indicator (BPI)

The BPI, a self-administered test to determine hemispheric dominance, consists of items that were normed on data obtained from EEG tests on dominance administered at the Biofeedback Institute of Denver.[33] In its final form, the self-administered version has been given to more than 500 people in so-called Wonder seminars. The results of this self-administered test have been shown to be correlated with comparable laboratory tests.[33] Subjects select the item that most closely represents their attitude or behavior. We deleted questions with multiple-choice answers and eliminated question 3; thus, the final self-administered test consisted of 32 questions. The answer to each question was assigned a score, and the sum of the average scores for all items ranged from 1 to 9. Average scores of 1 or 9 indicated high lateralization. In this study, we divided left-brain-dominant (<5) and right-brain dominant (>5), based on the middle average score 5.

2.7. Data analysis

Student's t-tests were used to analyze differences between 2 groups, and Pearson's correlation coefficients were used to analyze relationships between variables; p-values less than 0.05 were considered statistically significant.

3. Results

3.1. Study participants

Table 1 summarizes the demographic characteristics of the subjects, which shows the levels of stress, EI, IQ, BPI, and cytokines of the participants.

Table 1.

Demographic characteristics and the levels of stress, EI, IQ, BPI and cytokines of the participants.

3.1.

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3.2. Associations among stress, EI, and IQ

Our investigation of the relationships between stress and EI revealed negative correlations between stress and emotional awareness and expression (r = −0.324, P = .008), emotional thinking (r = −0.394, P = .001), and emotional regulation (r = −0.386, P = .001) (Fig. 1A, C, E). On the other hand, there were no significant correlations between stress and empathy and emotional application (Fig. 1B and D). High levels of anger were significantly associated with low levels of emotional regulation (r = −0.284, P = .022, Fig. 2). Our investigation of the correlations between emotion and IQ showed that emotional application was the only one of the 5 factors of EI to have positive correlations with the vocabulary (r = 0.292, P = .014), picture arrangement (r = 0.290, P = .015), block design (r = 0.252, P = .035), and full-scale IQ (r = 0.240, P = .045) scores (Fig. 3A–D). Interestingly, there was no significant correlation between stress and IQ, although stress was significantly correlated with EI and EI was significantly correlated with IQ.

Figure 1.

Figure 1

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The correlations between stress and EI. (A–E) n = 65. EI = emotional intelligence.

Figure 2.

Figure 2

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Association of anger in stress with emotional regulation. n = 65.

Figure 3.

Figure 3

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Correlations between emotional application and IQ. (A–D) n = 70, IQ = intelligence quotient.

3.3. Linear regression models for relationships among cytokines, stress, and IQ

We conducted linear regression analysis to elucidate relationships among the dependent variables and the independent variables including cytokines, stress, EI and IQ. We found linear regression models for understanding on complex and dynamic associations between them. The regression model for the full-scale IQ is “Y = 0.208X1 − 0.337X2 + 0.291X3 + 91.751” (Y: the full-scale IQ, X1: IL-10, X2: IL-6, X3: emotional application), indicating positive effects of IL-10 and emotional application and negative effects of IL-6 on the full-scale IQ in the total subjects (r = 0.402, adjusted R2 = 0.123, P = .009∗∗; Fig. 4A). And, the regression model for EI is “Y = −0.218X1 − 0.196X2 − 2.986X3 − 4.858X4 + 6.397X5 + 174.765” (Y: EI, X1: somatization stress, X2: depression stress, X3: vocabulary IQ, X4: arithmetic IQ, X5: vocabulary and arithmetic IQ), indicating positive effects of vocabulary and arithmetic IQ and negative effects of somatization and depression stress, and each vocabulary IQ or arithmetic IQ in the total subjects (r = 0.553, adjusted R2 = 0.247, P = .001∗∗, Fig. 4B). Additionally, we found linear regression models for understanding on complex and dynamic associations between them according to right-brain and left-brain dominance groups. In the left-brain dominance group, emotional thinking was affected negatively by somatization and depression stress, but positively by cognitive intelligence, showing regression model of “Y = −0.321X1 − 0.324X2 + 0.239X3 + 27.500” (Y: ET, X1: somatization stress, X2: depression stress, X3: Total VPBA) (r = 0.623, adjusted R2 = 0.343, P < 0.000∗∗∗; Fig. 5A). On the other hand, the full-scale IQ was affected negatively by anger stress, but positively by emotional application, showing the regression model of “Y = −0.331X1 + 0.535X2 + 70.241” (Y: the full-scale IQ, X1: anger stress, X2: emotional application) in the right-brain dominance group (r = 0.583, adjusted R2 = 0.263, P = .029∗; Fig. 5B). And, emotional thinking was affected positively by IL-10 and vocabulary and arithmetic IQ, but affected negatively by IL-6, each vocabulary and arithmetic IQ, showing the regression model of “Y = 0.664X1 − 0.382X2 − 3.755X3 − 4.447X4 + 6.403X5 + 37.297” (Y: Emotional Thinking, X1: IL-10, X2: IL-6, X3: vocabulary IQ, X4: arithmetic IQ, X5: vocabulary and arithmetic IQ) (r = 0.752, adjusted R2 = 0.430, P = .013∗; Fig. 5C).

Figure 4.

Figure 4

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Linear regression models for understanding EI and IQ in the total subjects. A, B) Blue arrows: negative contribution, Pink arrows: positive contribution. (A) n = 70, Y = 0.208X1 − 0.337X2 + 0.291X3 + 91.751, Y: IQ, X1: IL-10, X2: IL-6, X3: Emotional Application. B) n = 65, Y = −0.218X1–0.196X2–2.986X3–4.858X4+6.397X5+174.765, Y: EI, X1: somatization stress, X2: depression stress, X3: vocabulary IQ, X4: arithmetic IQ, X5: vocabulary and arithmetic IQ. EI = emotional intelligence, IQ = intelligence quotient.

Figure 5.

Figure 5

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Linear regression model for EI and IQ in the right and left-dominance groups. (A–C) Blue arrows: negative contribution, Pink arrows: positive contribution. (A) Left-brain dominance group, (B, C) right-brain dominance group. (A) n = 44, Y = −0.321X1 − 0.324X2 + 0.239X3 + 27.500, Y: ET, X1: somatization stress, X2: depression stress, X3: Total VPBA (V: Vocabulary IQ, P: Picture Arrangement IQ, B: Block Degisn IQ, A: Arithmetic IQ). B) n = 20, Y = −0.331X1 + 0.535X2 + 70.241. Y: IQ, X1: anger stress, X2: emotional application. C) n = 22, Y = 0.664X1 − 0.382X2 − 3.755X3 − 4.447X4 + 6.403X5 + 37.297. Y: Emotional Thinking, X1: IL-10, X2: IL-6, X3: vocabulary IQ, X4: arithmetic IQ, X5: vocabulary and arithmetic IQ. EI = emotional intelligence, IQ = intelligence quotient.

3.4. Correlations between stress and cytokines, and between cytokines and IQ

Next, we investigated the associations of cytokines with stress and IQ. First, we investigated the correlations between stress and cytokines. High IL-10 levels were significantly associated with low stress levels only in the right-brain-dominant group (r = −0.599, P = .005, Fig. 6A). Second, we analyzed correlations between cytokines and IQ. High scores on the arithmetic subtest were associated with high levels of IFN-gamma (r = 0.280, P = .019) and IL-10 (r = 0.304, P = .011) (Fig. 6B and C).

Figure 6.

Figure 6

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Correlations between cytokines and stress or arithmetic IQ. (A) n = 20, BPI: brain preference indicator, (B, C) n = 70. IQ = intelligence quotient.

3.5. Correlations between cytokines and IQ in the right-brain- and left-brain-dominance groups

We also analyzed the association of cytokines with intelligence according to hemispheric dominance using the BPI. Low scores on the vocabulary subtest were correlated with high levels of TNF-alpha (r = −0.300, P = .041) and IL-6 (r = −0.331, P = .023) (Fig. 7A and B) in left-brain-dominant subjects. Moreover, high full-scale IQ was related to low levels of the pro-inflammatory cytokine IL-6 (r = −0.327, P = .025, Fig. 7C). On the other hand, high scores on the arithmetic subtest were positively correlated with high levels of IFN-gamma (r = 0.363, P = .012) and IL-10 (r = 0.307, P = .036) in left-brain-dominant subjects (Fig. 7D and E). Similarly, high levels of the anti-inflammatory cytokine IL-10 were associated with high scores on the vocabulary (r = 0.467, P = .028) and vocabulary + arithmetic (r = 0.443, P = .039) subtests in right-brain-dominant subjects (Fig. 8A and B).

Figure 7.

Figure 7

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Correlations between cytokines and IQ in the left preference brain group. (A–E) n = 47, BPI = brain preference indicator, IQ = intelligence quotient.

Figure 8.

Figure 8

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Correlations between cytokines and IQ in the right preference brain group. (A, B) n = 22, BPI: brain preference indicator. IQ = intelligence quotient.

4. Discussion

We found that stress was associated with EI and EI was related to IQ. Through linear regression analysis, we elucidated the integrative contribution on the full-scale IQ, representing positive influence of anti-inflammatory cytokine, IL-10 and emotional application, while showing negative influence of pro-inflammatory cytokine, IL-6 in the total subjects. Also, we confirmed complex influence that the sum score of vocabulary and arithmetic IQ positively contributed on EI, while somatization and depression stress and each vocabulary IQ and arithmetic IQ negatively affected on EI. In addition, cytokines were associated with stress and intelligence, and the pro-inflammatory cytokines TNF-alpha and IL-6 negatively affected vocabulary and the full-scale IQ scores, and anti-inflammatory cytokines, such as IL-10 and IFN-gamma, positively affected scores on the vocabulary and arithmetic subtests. On the other hand, the relationships between cytokines and IQ differed according to hemispheric dominance.

High levels of stress were associated with low EI. Interestingly, of the 5 factors comprising EI, high levels of emotional awareness and expression, emotional thinking, and emotional regulation were associated with low levels of stress. On the other hand, empathy and emotional application were not related to stress. Thus, we suggest that high stress may reduce emotional awareness and expression, emotional thinking, and emotional regulation, and that high levels of EI may decrease stress because those with high levels of EI may use proactive and effective coping strategies when dealing with stress.[4] These results are consistent with previous reports describing that higher EI is significantly related to lower stress.[6,7] Not surprisingly, high levels of anger, one contributor to stress, were related to low levels of emotional regulation. Thus, low levels of emotional regulation may lead to high levels of anger.

EI influences stress level, ability to perform tasks, and effectiveness when working with others,[8] and the importance of IQ and EI in cognitive control processes has been established.[11] Participants with a higher self-reported EI were able to perform more cognitive tasks and did so more effectively than those with lower EI.[34] Internalized and externalized emotional dysfunction were not related to WAIS-IV full-scale IQ or verbal comprehension, perceptual reasoning, working memory, and processing speed scores; however, fear level, which includes health-related preoccupations and distorted perceptions, was significantly related to WAIS-IV full-scale IQ and verbal comprehension scores.[35] General intelligence is also negatively affected by psychopathology.[36] Among the 5 subscales comprising EI, only emotional application was associated with increased full-scale IQ scores and increased scores on the vocabulary, picture arrangement, and block design subtests. Emotional application includes abilities related to discriminating among, thinking about, and understanding various emotional states and different kinds of emotion. Future research should investigate why only emotional application was correlated with IQ.

Pro-inflammatory cytokine, IL-6 level has been associated with acute psychosocial stress in humans,[37] and decreased IL-10 expression was found in the hippocampus of stressed mice.[38] In this study, high levels of IL-10 were associated with low levels of stress. Thus, stress may affect the increase of pro-inflammatory cytokines and, at the same time, anti-inflammatory cytokines, such as IL-10, may contribute to the protection from stress.

Blunted HPA axis reactivity is associated with low intelligence in children with attention-deficit/hyperactivity disorder.[39] Circulating levels of TNF-alpha, sTNFRs, and IL-6 were negatively correlated with IQ at age 85.[40] In this study, IL-10 and IFN-gamma were related to high scores on the arithmetic subtest. Thus, we can infer that pro-inflammatory cytokines may negatively affect IQ and that anti-inflammatory cytokines may positively affect IQ. Additionally, better cognitive control following an emotional stressor is uniquely associated with less pronounced pro-inflammatory cytokine reactivity to such stress.[41] Therefore, cognitive control may decrease stress and pro-inflammatory cytokines but may increase anti-inflammatory cytokines and IQ.

The specific features that may affect IQ include the size and shape of the frontal lobes. Indeed, structural and functional brain-imaging studies have found differences in the brain pathways, especially especially parieto-frontal pathways that contribute to intelligence differences.[42] Interestingly, although we found correlations between cytokine levels and IQ scores, these associations differed according to hemispheric dominance. That is, in the left-brain-dominant group, high levels of pro-inflammatory cytokines, such as TNF-alpha and IL-6, were related to low full-scale IQ and vocabulary scores, whereas high levels of anti-inflammatory cytokines, such as IL-10 and IFN-gamma, were associated with high arithmetic scores. On the other hand, in the right-brain-dominant group, high levels of IL-10 were associated with high arithmetic and vocabulary scores. The activities of the HPA axis are related to behavioral lateralization and brain asymmetry, and brain IL-6 may be a mediator of the asymmetrical immunomodulation by the central nervous system.[43] The asymmetry of hemispheric volume has been related to verbal IQ minus performance IQ.[44] Thus, these hemispheric differences likely reflect differences in the mechanisms underpinning the relationships between the immune system and cognitive intelligence and warrant further exploration in the future.

Higher trait EI which refers to the individual differences in the perception, processing, regulation and utilization of emotional information were significantly associated with lower reactivity to stress at both psychological and biological levels.[45] The emotional–cognitive interaction in stress, which has been established,[46] involves relationships among stress, emotion, and cognitive intelligence. The importance of functional connectivity within the limbic–frontal circuitry during emotional regulation has been reported,[47] and the structural and functional brain networks related to IQ have been identified.[48,49] Thus, the close relationships among stress, emotion, and IQ have been established and proven by research in fields such as psychology and biology and research on structural and functional connectivity in the brain. Interestingly, although significant correlations between stress and EI and between EI and IQ were found, no significant correlation between stress and IQ was observed. We can infer that this result may be related to brain structure. The HPA axis, which is related to stress,[19,20] is closely connected to the limbic area, which is associated with emotion[50]; moreover, the limbic area is directly connected with the frontal cortex and the brain pathways related to IQ.[18,42] That is, it is possible that stress is not significantly correlated with IQ because the HPA axis is not directly structurally connected with the frontal cortex and the brain pathways most strongly implicated in intelligence. Furthermore, higher levels of inflammation are associated with longitudinal changes in brain function in regions important for cognition.[51] Therefore, stress, emotion, cognitive intelligence, and the status of the inflammatory system seem to be both structurally and functionally very strongly associated with one another, leading to interactions between psychological and biological functions. Actually, we demonstrated these integrative associations among cytokines, stress, emotional and cognitive intelligence by using linear regression analysis. We confirmed that anti-inflammatory cytokine such as IL-10 has positive influence on emotional and cognitive intelligence, while pro-inflammatory cytokine such as IL-6 shows negative influence on them, supporting bodily healthy immune function is closely associated with emotional and cognitive intelligence. Also, we confirmed negative influence of stress on emotional and cognitive intelligence. Furthermore, we demonstrated different associations among cytokines, stress, emotional, and cognitive intelligence according to right-brain and left-brain dominance, which can demonstrate that right and left hemisphere is differentiated on emotional and cognitive intelligence.

There are a few limitations in this study that should be noted, particularly concerning multiple correlations. Multiple correlations can be accounted for with Bonferroni and other corrections, or by the approach of controlling the false discover rate, but these approaches are not always needed, given that reducing the type I error for null associations increases the type II error for those associations that are not null.[52,53] Thus, we used a rather liberal threshold for significance in correlation analysis, although requires a stricter significance threshold for individual comparisons, so as to compensate for the number of inferences being made. We may miss important findings when we stick to corrections for multiple correlations. Thus, our exploratory analyses may be meaningful for the further study. Another limitation is that correlation does not imply causation, but we can also infer causation with regression models we suggest in this study.

In conclusion, we found significant correlations between stress and EI and between EI and IQ. These results can show integrative associations among stress, EI and cognitive intelligence, supporting complex interactions related to the structure and function of brain. Moreover, the pro-inflammatory cytokines TNF-alpha and IL-6 negatively affected stress and intelligence, and anti-inflammatory cytokines, such as IL-10 and IFN-gamma, positively affected these factors. Additionally, as these relationships between cytokines and IQ differed depending on hemispheric dominance, additional research is needed to explore the interactions and mechanisms that lead to hemispheric differences in stress, inflammation, emotion, and IQ.

Acknowledgments

This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. NRF-2018R1A2B6001806).

Author contributions

Conceptualization: Ye-Ha Jung.

Data curation: Na Young Shin, Do-Hyung Kang.

Formal analysis: Ye-Ha Jung.

Funding acquisition: Do-Hyung Kang.

Investigation: Ye-Ha Jung, Na Young Shin.

Methodology: Ye-Ha Jung, Na Young Shin, Yoobin Choi.

Project administration: Ye-Ha Jung, Do-Hyung Kang.

Supervision: Soo-Hee Choi, Do-Hyung Kang.

Visualization: Dasom Lee.

Writing – original draft: Ye-Ha Jung.

Writing – review & editing: Ye-Ha Jung, Joon Hwan Jang, Won Joon Lee, Soo-Hee Choi, Do-Hyung Kang.

Supplementary Material

Supplemental Digital Content

Footnotes

Abbreviations: BPI = brain preference indicator, EI = emotional intelligence, HPA axis = hypothalamo–pituitary–adrenocortical axis, IQ = intelligence quotient, SRI = stress response inventory.

The authors declare no competing interests.

The English in this document has been checked by at least 2 professional editors, both native speakers of English. For a certificate, please see: http://www.textcheck.com/certificate/4CVP96.

The authors have no conflicts of interest to disclose.

Supplemental Digital Content is available for this article.

References

  • [1].Ulrich-Lai YM, Herman JP. Neural regulation of endocrine and autonomic stress responses. Nat Rev Neurosci 2009;10:397–409. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [2].Schneiderman N, Ironson G, Siegel SD. Stress and health: psychological, behavioral, and biological determinants. Annu Rev Clin Psychol 2005;1:607–28. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [3].Sharma J, Dhar RL, Tyagi A. Stress as a mediator between work-family conflict and psychological health among the nursing staff: moderating role of emotional intelligence. Appl Nurs Res 2015;pii: S0897-1897(15)00048-8. [DOI] [PubMed] [Google Scholar]
  • [4].Por J, Barriball L, Fitzpatrick J, et al. Emotional intelligence: its relationship to stress, coping, well-being and professional performance in nursing students. Nurse Educ Today 2011;31:855–60. [DOI] [PubMed] [Google Scholar]
  • [5].Salovey P, Mayer JD. Emotional intelligence. Imagin Cogn Pers 1989;9:185–211. [Google Scholar]
  • [6].Görgens-Ekermans G, Brand T. Emotional intelligence as a moderator in the stress-burnout relationship: a questionnaire study on nurses. J Clin Nurs 2012;21:2275–85. [DOI] [PubMed] [Google Scholar]
  • [7].Mitra S, Sarkar AP, Haldar D, et al. Correlation among perceived stress, emotional intelligence, and burnout of resident doctors in a medical college of West Bengal: a mediation analysis. Indian J Public Health 2018;62:27–31. [DOI] [PubMed] [Google Scholar]
  • [8].Pisanos DE. Emotional intelligence: it's more than IQ. J Contin Educ Nurs 2011;42:439–40. [DOI] [PubMed] [Google Scholar]
  • [9].Jonsdottir IH, Nordlund A, Ellbin S, et al. Cognitive impairment in patients with stress-related exhaustion. Stress 2013;16:181–90. [DOI] [PubMed] [Google Scholar]
  • [10].Gavelin HM, Boraxbekk CJ, Stenlund T, et al. Effects of a process-based cognitive training intervention for patients with stress-related exhaustion. Stress 2015;18:578–88. [DOI] [PubMed] [Google Scholar]
  • [11].Checa P, Fernández-Berrocal P. The role of intelligence quotient and emotional intelligence in cognitive control processes. Front Psychol 2015;6:1853. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [12].Ouyang W, Rutz S, Crellin NK, et al. Regulation and functions of the IL-10 family of cytokines in inflammation and disease. Annu Rev Immunol 2011;29:71–109. [DOI] [PubMed] [Google Scholar]
  • [13].Landskron G, De la Fuente M, Thuwajit P, et al. Chronic inflammation and cytokines in the tumor microenvironment. J Immunol Res 2014;2014:149185. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [14].Sordillo PP, Sordillo LA, Helson L. Bifunctional role of pro-inflammatory cytokines after traumatic brain injury. Brain Inj 2016;30:1043–53. [DOI] [PubMed] [Google Scholar]
  • [15].Dubový P, Jančálek R, Kubek T. Role of inflammation and cytokines in peripheral nerve regeneration. Int Rev Neurobiol 2013;108:173–206. [DOI] [PubMed] [Google Scholar]
  • [16].Kohman RA, Rhodes JS. Neurogenesis, inflammation and behavior. Brain Behav Immun 2013;27:22–32. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [17].Kim YK, Won E. The influence of stress on neuroinflammation and alterations in brain structure and function in major depressive disorder. Behav Brain Res 2017;329:6–11. [DOI] [PubMed] [Google Scholar]
  • [18].Butler O, Yang XF, Laube C, et al. Community violence exposure correlates with smaller gray matter volume and lower IQ in urban adolescents. Hum Brain Mapp 2018;39:2088–97. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [19].Gu HF, Tang CK, Yang YZ. Psychological stress, immune response, and atherosclerosis. Atherosclerosis 2012;223:69–77. [DOI] [PubMed] [Google Scholar]
  • [20].Chen X, Gianferante D, Hanlin L, et al. HPA-axis and inflammatory reactivity to acute stress is related with basal HPA-axis activity. Psychoneuroendocrinology 2017;78:168–76. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [21].John CD, Buckingham JC. Cytokines: regulation of the hypothalamo-pituitary-adrenocortical axis. Curr Opin Pharmacol 2003;3:78–84. [DOI] [PubMed] [Google Scholar]
  • [22].Haimovici F, Anderson JL, Bates GW, et al. Stress, anxiety, and depression of both partners in infertile couples are associated with cytokine levels and adverse IVF outcome. Am J Reprod Immunol 2018;79:e12832. [DOI] [PubMed] [Google Scholar]
  • [23].Himmerich H, Fischer J, Bauer K, et al. Stress-induced cytokine changes in rats. Eur Cytokine Netw 2013;24:97–103. [DOI] [PubMed] [Google Scholar]
  • [24].Costanzo EY, Villarreal M, Drucaroff LJ, et al. Hemispheric specialization in affective responses, cerebral dominance for language, and handedness: Lateralization of emotion, language, and dexterity. Behav. Brain Res 2015;288:11–9. [DOI] [PubMed] [Google Scholar]
  • [25].Esteves M, Marques P, Magalhães R, et al. Structural laterality is associated with cognitive and mood outcomes: An assessment of 105 healthy aged volunteers. Neuroimage 2017;153:86–96. [DOI] [PubMed] [Google Scholar]
  • [26].Gotts SJ, Jo HJ, Wallace GL, et al. Two distinct forms of functional lateralization in the human brain. Proc Natl Acad Sci U S A 2013;110:E3435–44. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [27].Koh KB, Park JK, Kim CH, et al. Development of the stress response inventory and its application in clinical practice. Psychosom Med 2001;63:668–78. [DOI] [PubMed] [Google Scholar]
  • [28].Choi SM, Kang TY, Woo JM. Development and validation of a modified form of the stress response inventory for workers. J Korean Neuropsychiatr Assoc 2006;45:541–53. [Google Scholar]
  • [29].Moon Y. Report of the Saehan Media EQ Test. Seoul: Saehan Media; 1999. [Google Scholar]
  • [30].Mayer JD, Salovey P. What is emotional intelligence? Emotional development and emotional intelligence: Educational implications. 1997;New York: Harper Collins, 3–34. [Google Scholar]
  • [31].Kaufman AS, Lichtenberger EO. Assessing Adolescent and Adult Intelligence. 3rd edn2005;Hoboken (NJ): Wiley, 3. [Google Scholar]
  • [32].Lee YS, Kim ZS. Validity of short forms of the Korean-Wechsler Adult Intelligence Scale. Korean J Clin Psychol 1995;14:111–6. [Google Scholar]
  • [33].Wonder J, Donovan P. Whole-brain Thing. 1984;New York: Quill, 21–41. [Google Scholar]
  • [34].Schutte NS, Schuettpelz E, Malouff JM. Emotional intelligence and task performance. Imagin Cogn Pers 2001;20:347–54. [Google Scholar]
  • [35].Gass CS, Gutierrez L. Psychological variables and Wechsler Adult Intelligence Scale-IV performance. Appl Neuropsychol Adult 2017;24:357–63. [DOI] [PubMed] [Google Scholar]
  • [36].Gaines T, Jr, Morris R. Relationships between MMPI measures of psychopathology and WAIS subtest scores and intelligence quotients. Percept Mot Skills 1978;47:399–402. [DOI] [PubMed] [Google Scholar]
  • [37].Quinn AM, Williams AR, Sivilli TI, et al. The plasma interleukin-6 response to acute psychosocial stress in humans is detected by a magnetic multiplex assay: comparison to high-sensitivity ELISA. Stress 2018;13:1–6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [38].Labaka A, Gómez-Lázaro E, Vegas O, et al. Reduced hippocampal IL-10 expression, altered monoaminergic activity and anxiety and depressive-like behavior in female mice subjected to chronic social instability stress. Behav. Brain Res 2017;335:8–18. [DOI] [PubMed] [Google Scholar]
  • [39].Shin DW, Lee SH. Blunted hypothalamo-pituitary-adrenal axis reactivity is associated with the poor intelligence performance in children with attention-deficit/hyperactivity disorder. Neuropediatrics 2007;38:298–303. [DOI] [PubMed] [Google Scholar]
  • [40].Krabbe KS, Mortensen EL, Avlund K, et al. Genetic priming of a proinflammatory profile predicts low IQ in octogenarians. Neurobiol Aging 2009;30:769–81. [DOI] [PubMed] [Google Scholar]
  • [41].Shields GS, Kuchenbecker SY, Pressman SD, et al. Better cognitive control of emotional information is associated with reduced pro-inflammatory cytokine reactivity to emotional stress. Stress 2016;19:63–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [42].Deary IJ, Penke L, Johnson W. The neuroscience of human intelligence differences. Nat Rev Neurosci 2010;11:201–11. [DOI] [PubMed] [Google Scholar]
  • [43].Shen YQ, Hébert G, Moze E, et al. Asymmetrical distribution of brain interleukin-6 depends on lateralization in mice. Neuroimmunomodulation 2005;12:189–94. [DOI] [PubMed] [Google Scholar]
  • [44].Yeo RA, Turkheimer E, Raz N, et al. Volumetric asymmetries of the human brain: intellectual correlates. Brain Cogn 1987;6:15–23. [DOI] [PubMed] [Google Scholar]
  • [45].Mikolajczak M, Roy E, Luminet O, et al. The moderating impact of emotional intelligence on free cortisol responses to stress. Psychoneuroendocrinology 2007;32:1000–12. [DOI] [PubMed] [Google Scholar]
  • [46].Dolcoş F, Strungaru C, Dolcoş SM, et al. The involvement of endogenous opiates in emotional-cognitive interaction in stress. Rom J Physiol 1998;35:259–74. [PubMed] [Google Scholar]
  • [47].Banks SJ, Eddy KT, Angstadt M, et al. Amygdala-frontal connectivity during emotion regulation. Soc Cogn Affect Neurosci 2007;2:303–12. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [48].Simos PG, Rezaie R, Papanicolaou AC, et al. Does IQ affect the functional brain network involved in pseudoword reading in students with reading disability? A magnetoencephalography study. Front Hum Neurosci 2014;7:932. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [49].Navas-Sánchez FJ, Alemán-Gómez Y, Sánchez-Gonzalez J, et al. White matter microstructure correlates of mathematical giftedness and intelligence quotient. Hum Brain Mapp 2014;35:2619–31. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [50].Morgane PJ, Galler JR, Mokler DJ. A review of systems and networks of the limbic forebrain/limbic midbrain. Prog Neurobiol 2005;75:143–60. [DOI] [PubMed] [Google Scholar]
  • [51].Warren KN, Beason-Held LL, Carlson O, et al. Elevated markers of inflammation are associated with longitudinal changes in brain function in older adults. J Gerontol A Biol Sci Med Sci 2018;73:770–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • [52].Rothman KJ. No adjustments are needed for multiple comparisons. Epidemiology 1990;1:43–6. [PubMed] [Google Scholar]
  • [53].Saville DJ. Multiple comparison procedures: the practical solution. Am Stat 1990;44:174–80. [Google Scholar]

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