Neuroticism and extraversion in relation to physiological stress reactivity during adolescence

Highlights

• Neuroticism and extraversion were reported five times during adolescence.

• Physiological stress reactivity was examined during a psychosocial stressor.

• Personality predicted stress reactivity with dual latent growth curve modelling.

• Neuroticism was related to stronger pre-ejection period reactivity.

• Extraversion was related to lower cortisol reactivity.

Abstract

The current study examined mean level and change in extraversion and neuroticism across adolescence in relation to physiological stress reactivity to social evaluation. Adolescents (n = 327) from the Dutch general population reported on personality measures at five annual assessments. At age 17 years, adolescents participated in a psychosocial stress procedure characterized by social evaluation during which cortisol, heart rate, pre-ejection period (PEP) and heart rate variability were assessed. Dual latent growth curve models were fitted in which the intercepts (mean level) and slopes (change) of personality across adolescence predicted the intercepts (baseline) and slopes (reactivity) of the physiological stress measures. Most comparisons revealed no relation between personality and stress reactivity. Adolescents with higher mean level scores on extraversion did show lower cortisol reactivity. Adolescents with higher mean level neuroticism scores showed higher PEP reactivity. Our findings lend partial support for a relation between personality and physiological stress reactivity.

Introduction

Hans Selye’s and Walter Cannon’s pivotal work showed that the physiological stress response is the body’s adaptive manner of handling internal and environmental imbalance (Cannon, 1929; Selye, 1950). When confronted with a stressor, autonomic nervous system (ANS) and hypothalamic-pituitary-adrenal (HPA) axis activation prepare the individual for and facilitate an appropriate response (i.e. stress reactivity). It is widely understood that individuals vary in their responses to stress, and many factors contribute to this variation. For instance, specific genes (e.g. Mueller, Strahler, Armbruster, Lesch, Brocke, & Kirschbaum, 2012), gender (e.g. Ordaz & Luna, 2012), body mass index (BMI; Carroll, Phillips, & Der, 2008), socioeconomic status (SES; Miller et al., 2009) and pubertal stage (Gunnar, Wewerka, Frenn, Long, & Griggs, 2009; van den Bos, de Rooij, Miers, Bokhorst, & Westenberg, 2014) have all been shown to influence the magnitude of the physiological and/or perceived stress response. Furthermore, stress responses and the influence of these factors on stress responses may not be uniform across different stages of development (e.g. Evans, Greaves-Lord, Euser, Tulen, Franken, & Huizink, 2013; Gunnar et al., 2009). Despite the recognized influence of these factors, a large portion of the variance in individual stress responses remains unexplained. One potential factor that may further add to clarification of this variance is personality or trait differences, most notably neuroticism and extraversion due to the wealth of theory and previous research on these particular constructs.

The human stress response systems, the ANS and the HPA axis, are phylogenetically old and complex. The ANS consists of two branches: the parasympathetic nervous system (PNS) and the sympathetic nervous system (SNS). The vagus nerve of the PNS is responsible for maintaining homeostasis and supporting social engagement during rest and plays a central role in emotion regulation (Porges, 1995, Porges, 2007; Porges, Doussard-Roosevelt, & Maiti, 1994). When an organism is confronted with a stressor, the most immediate response involves vagal withdrawal, indicating the organism’s preparedness to respond to an anticipated stressor. Vagal activation is often indexed by heart rate variability (HRV), which is high during rest (PNS activation) and low during stress (vagal withdrawal). If the response of vagal withdrawal is insufficient, the SNS is activated, entailing the fight-or-flight response which, among other functions, increases heart rate, blood pressure, and secretion of adrenaline and noradrenaline. This hierarchy of responses is consistent with the Jacksonion principle of dissolution (Jackson, 1958, Porges, 2007). Pre-ejection period (PEP) is frequently utilized as an index of SNS activation and marks the time interval in milliseconds between the beginning of the ventricular depolarization and the beginning of the ventricular ejection. Shorter intervals thus indicate stronger sympathetic activation. Furthermore, PEP is thought to be an index of the dopaminergic response to reward (Beauchaine, 2012). The heart is innervated by both the PNS and SNS. These branches operate independently of one another, and usually exert reciprocal influences on the heart (Berntson, Cacioppo, & Quigley, 1991). Heart rate thus indexes combined PNS and SNS (de) activation.

The response of the HPA axis entails the production of corticotropin-releasing hormone by neurons in the paraventricular nucleus (PVN) of the hypothalamus. This stimulates the secretion of adrenocorticotrophic hormone in the pituitary which in turn stimulates the secretion of cortisol in the outer cortex of the adrenal gland. On normal days, the cortisol levels of healthy individuals follow a diurnal curve with an acrophase approximately 30 min after awakening and a subsequent gradual decrease (Schmidt-Reinwald et al., 1999). When confronted with a stressful situation, the adaptive response of a healthy individual is a temporary increase in the secretion of cortisol which is observable in saliva about 20 min following the onset of the stressor (Sapolsky, Romero, & Munck, 2000). Ultimately, the human stress response is an intricately complex series of events, with activation of the ANS and HPA axis beginning in the PVN (Benarroch, 2005, Joels and Baram, 2009). This is followed immediately by observable physiological changes in ANS functioning (i.e. vagal withdrawal followed by increased heart rate and blood pressure, a shortening of the PEP) and subsequent increases in salivary cortisol levels after some time (Joels & Baram, 2009; Sapolsky et al., 2000).

In an influential biopsychological theory of personality, Hans J. Eysenck proposed that extraversion and neuroticism are independent constructs characterized by differential physiological responses and that distinct biological substrates underlie these responses (Eysenck, 1967; Eysenck & Eysenck, 1985). He hypothesized that neuroticism is related to hyper-arousability of the limbic system, which is implicated in the processing of emotions related to the SNS fight-or-flight response. Therefore it might be expected that individuals scoring high on neuroticism scales would respond physiologically strongly to a stressor, and perhaps in particular when measuring SNS responses. In contrast, extraversion was hypothesized to be associated with hypo-arousability of principally the reticulo-cortical loop and other arousal systems such as the monoamine oxidase system or the pituitary-adrenocortical system (Eysenck, 1967; Eysenck & Eysenck, 1985; Hagemann, Naumann, Lurken, Becker, Maier, & Bartussek, 1999). Individuals scoring high on extraversion may thus be less physiologically responsive to stress than those scoring high on introversion. Especially when the stressor contains social-evaluative elements, extraverts may respond less strongly to the stressor because of their tendency to experience positive affect and to be less inhibited in social situations (Eysenck & Eysenck, 1985).

Emotion regulation may play a key role in the relation between stress reactivity and personality. The ANS (e.g. Porges, 2007; Porges et al., 1994) and the HPA axis (e.g. Stansbury & Gunnar, 1994) are both implicated in emotion regulation capabilities. Extraversion and neuroticism are also characterized by emotion regulation abilities: extraverts tend to be able to effectively regulate their emotions (Jonassaint et al., 2009) while individuals scoring higher on neuroticism are not (e.g. Ormel et al., 2013). Physiological stress reactivity, personality, and emotion regulation capabilities may thus be interrelated, with bidirectional relations proposed between each relation (e.g. Koole, 2009; Porges, 2007; Porges et al., 1994; Stansbury & Gunnar, 1994).

Numerous empirical examinations of a relation between physiological reactivity and personality have been executed since the late 1960s, however yielding inconclusive results (Ormel et al., 2013; Pearson & Freeman, 1991). For example, neuroticism has been linked to physiological hyper-reactivity (e.g. Habra, Linden, Anderson, & Weinberg, 2003), but also to hypo-reactivity (e.g. Chida & Hamer, 2008; Phillips, Carroll, Burns, & Drayson, 2005). Extraversion, too, has been linked to physiological hypo-reactivity (e.g. Gange, Geen, & Harkins, 1979; Jonassaint et al., 2009; Kirschbaum et al., 1995) as well as hyper-reactivity (e.g. Oswald, Zandi, Nestadt, Potash, Kalaydjian, & Wand, 2006). However, the majority of studies failed to find an association between physiological reactivity and neuroticism and/or extraversion (e.g. Arnetz & Fjellner, 1986; Garcia-Banda et al., 2011; Glass, Lake, Contrada, Kehoe, & Erlanger, 1983; Kirschbaum, Bartussek, & Strasburger, 1992; Schommer, Kudielka, Hellhammer, & Kirschbaum, 1999).

Yet, methodological considerations of previous studies preclude dismissing this potential association. Most included small samples and utilized few physiological measurements. The type of stressor used varies greatly; early studies tested the response to visual vigilance tasks (e.g. Gange et al., 1979) or non-laboratory stressors such as lecturing (e.g. Houtman & Bakker, 1991), and many utilized mental arithmetic tasks (e.g. Pearson & Freeman, 1991). Given that tasks containing social-evaluative threat and uncontrollability are most likely to induce a physiological response (Dickerson & Kemeny, 2004), other types of stressors may be less effective herein. Psychosocial stress tasks such as the Trier Social Stress Task (Kirschbaum, Pirke, & Hellhammer, 1993) and the Leiden Public Speaking Task (PST; Westenberg et al., 2009), in which social evaluation is focal, may be more ecologically valid as well as more suited to examining the relation between physiological reactivity and personality (Kamarck & Lovallo, 2003). Only a few studies have utilized such tasks to investigate the physiological correlates of personality (e.g. Garcia-Banda et al., 2011; Kirschbaum et al., 1992), though yielded inconclusive findings, and further research of this line is warranted.

Furthermore, the majority of this research has been performed in adults, whereas the relation between stress reactivity and personality may be especially paramount during adolescence (Charmandari, Kino, Souvatzoglou, & Chrousos, 2003). Indeed, adolescence is considered a sensitive period, critical in the development of both personality traits (Klimstra, Hale, Raaijmakers, Branje, Meeus, 2009) and physiological stress reactivity (Klein and Romeo, 2013, Romeo, 2010). To our knowledge, only two studies examined physiological stress reactivity and personality in adolescent samples. Laceulle and colleagues (Laceulle, Nederhof, van Aken, & Ormel, 2015) found that neuroticism and extraversion were not related to cortisol reactivity to a psychosocial stressor, but were related to basal cortisol levels. Similarly, Zahn, Kruesi, Leonard, & Rapoport, 1994 found that extraversion scores were unrelated to heart rate responses to a reaction time task. Considering that social evaluation becomes an increasingly prominent concern in adolescence (Westenberg et al., 2004), examining the physiological response to psychosocial stressors in relation to personality traits during adolescence is pertinent.

When studying the link between personality traits and stress in adolescence, it may be necessary to take into account possible changes in personality across the adolescent years. Indeed, personality traits may not be as stable (i.e. mean-level stability) as previously thought (Groothuis & Trillmich, 2011), and may shift during adolescence (Branje, Van Lieshout, & Gerris, 2007; Klimstra et al., 2009; McAdams & Olson, 2010) and early adulthood before becoming gradually more stable across middle and later adulthood (Roberts, Walton, & Viechtbauer, 2006). The prefrontal cortex plays a major part in regulating behavioral inhibition, which is implicated in personality (Koolhaas, de Boer, Buwalda, & van Reenen, 2007). As the prefrontal cortex continues to undergo maturation throughout adolescence (Giedd et al., 1999), we can expect personality to continue to develop during this period as well (Groothuis & Trillmich, 2011). Therefore, in the present study we considered both mean level and change in personality scores across adolescence.

This study aimed to examine the personality traits extraversion and neuroticism in relation to physiological stress reactivity during a psychosocial stressor, characterized by social evaluation, in a large sample of adolescents from the general population. General consensus currently points to five personality traits (i.e. the Big Five; Costa & McCrae, 1988). However, in the current study we chose to focus on extraversion and neuroticism in particular because our research questions and hypotheses are rooted in Eysenck’s theory of these two constructs, and given the wealth of previous research that has been done on the relation between these two constructs and physiological stress reactivity. As personality traits may be differentially related to ANS and HPA axis responding, we included measures of both systems. In order to index ANS reactivity, we measured heart rate (HR), PEP and HRV. We included HR because we were mainly interested in overall ANS responding, and HR indexes combined sympathetic and parasympathetic activation. We included PEP and HRV in order to gain more insight into sympathetic and parasympathetic activation specifically. In order to index HPA axis reactivity, we collected salivary cortisol samples. In a series of dual process growth curve models, we examined to what extent individual differences in mean level and change in personality scores across adolescence predicted individual differences in physiological stress levels at baseline and during the psychosocial stressor, which took place in late adolescence. Following Eysenck’s (1967) theory, we hypothesized that neuroticism would be related to higher stress reactivity and that extraversion would be related to lower stress reactivity.