Executive functioning performance predicts subjective and physiological acute stress reactivity: Preliminary results

Abstract

Individual differences in baseline executive functioning (EF) capacities have been shown to predict state anxiety during acute stressor exposure. However, no previous studies have clearly demonstrated the relationship between EF and physiological measures of stress. The present study investigated the efficacy of several well-known EF tests (letter fluency, Stroop test, and Wisconsin Card Sorting Test) in predicting both subjective and physiological stress reactivity during acute psychosocial stress exposure. Our results show that letter fluency served as the best predictor for both types of reactivity. Specifically, the higher the letter fluency score, the lower the acute stress reactivity after controlling for the baseline stress response, as indicated by lower levels of state anxiety, negative mood, salivary cortisol, and skin conductance. Moreover, the predictive power of the letter fluency test remained significant for state anxiety and cortisol indices even after further adjustments for covariates by adding the body mass index (BMI) as a covariate. Thus, good EF performance, as reflected by high letter fluency scores, may dampen acute stress responses, which suggests that EF processes are directly associated with aspects of stress regulation.

Introduction

A multifaceted neuropsychological construct known as executive functioning (EF) has been associated with a set of higher-order neurocognitive processes, including set formation, set maintenance, and set shifting. These processes allow us to initiate planning, execute appropriate actions, generate problem solving strategies, monitor and modify ongoing behavior in response to environmental changes, and regulate emotional responses, thereby enabling us to successfully engage in purposeful, goal-directed, and future-oriented behaviors (Suchy, 2009, Zelazo and Cunningham, 2007).

Research has consistently demonstrated associations between acute stress or trauma exposure and poorer EF (Williams et al., 2009, DePrince et al., 2009, Horwitz and McCaffrey, 2008). However, less is known about the effect of EF deficits assessed before stress exposure on significantly inducing stress responses. Larsson et al. (2007) asserted that poorer baseline letter fluency performance, indicating a lack of effective attentional control toward perceptual stimuli or memory representations that is likely related to a poorer retrieval of verbal coping strategies in response to stress, is associated with a higher level of anxiety experienced during a threatening situation. Furthermore, lower baseline verbal fluency scores induce greater motor responses when warned of the impending startle, which indicates poorer emotion–regulation abilities (Gyurak et al., 2009). With respect to the severity of post-traumatic stress disorder (PTSD) symptoms, the presence of neurocognitive impairments in trauma-exposed individuals with PTSD is not merely an impact of neurobiological changes produced by severe stress (Leskin and White, 2007, LaGarde et al., 2010, Koso and Hansen, 2006) but rather the result of subtle deficits that exist prior to trauma exposure that may act as risk factors for the development of PTSD (Parslow and Jorm, 2007, Marx et al., 2009).

The limited studies described above have successfully elucidated psychological and somatic aspects of stress reactivity, as indicated by questionnaires, interviews, and motor responses. However, to our knowledge, no previous studies have demonstrated the predictive power of baseline EF capacities related to the level of physiological stress reactivity during acute stressor exposure. Exposure to acute stress increases autonomic responses and is accompanied by the activation of the hypothalamic–pituitary–adrenal (HPA) axis, which is known to be influenced by the prefrontal cortex (PFC) (responsible for EF) and the amygdala. Specifically, in relation to stress regulation, increased metabolic glucose rate in the medial PFC (mPFC) area during acute psychosocial stressor exposure is inversely associated with a decreased metabolic glucose rate in areas more lateral to the mPFC and amygdala/hippocampal region as well as stress-induced salivary cortisol secretions (Kern et al., 2008).

Our study investigated the ability of several well-known EF tests, including letter fluency, the Stroop test, and the Wisconsin Card Sorting Test (WCST), to predict multilevel stress responses. These three tasks were chosen because they are among the most frequently used EF measures in both research and practice (reviewed in Alvarez and Emory, 2006). A total of 32 university students were recruited to participate in an experimental session scheduled to take place within one month (M = 11.91 days, SD = 8.10) after assessment of their EF capacities. The Trier Social Stress Test (TSST), consisting of speech preparation, speech delivery, and mental arithmetic, was used to induce acute psychological stress responses. To assess the effects of stress induction, heart rate (HR), skin conductance level (SCL), salivary cortisol, and behavioral data were collected throughout the experiment. We predicted that higher EF performance would decrease both behavioral and physiological stress reactivity.