The effects of acute stress on core executive functions: A meta-analysis and comparison with cortisol

Abstract

Core executive functions such as working memory, inhibition, and cognitive flexibility are integral to daily life. A growing body of research has suggested that acute stress may impair core executive functions. However, there are a number of inconsistencies in the literature, leading to uncertainty about how or even if acute stress influences core executive functions. We addressed this by conducting a meta-analysis of acute stress effects on working memory, inhibition, and cognitive flexibility. We found that stress impaired working memory and cognitive flexibility, whereas it had nuanced effects on inhibition. Many of these effects were moderated by other variables, such as sex. In addition, we compared effects of acute stress on core executive functions to effects of cortisol administration and found some striking differences. Our findings indicate that stress works through mechanisms aside from or in addition to cortisol to produce a state characterized by more reactive processing of salient stimuli but greater control over actions. We conclude by highlighting some important future directions for stress and executive function research.

Keywords: Acute stress; Cognitive control; Cognitive flexibility; Cortisol; Executive function; Inhibition; Interference control; Meta-analysis; Response inhibition; Set shifting; Working memory.

Copyright © 2016 Elsevier Ltd. All rights reserved.

Figures

Figure 1

Funnel plots to ascertain evidence for publication bias. Asymmetry of points around the line by the standard error indicates evidence for publication bias. Lightgray bars represent 95% confidence intervals; gray bars represent 99% confidence intervals. Only working memory showed any evidence of publication bias, but this was driven by the outlying study (see graph). Once this outlier was removed, stress effects on working memory showed no evidence of publication bias.

Figure 2

Effect of stress effect on working memory. Acute stress significantly impaired working memory. Size of the square indicates the relative weight assigned to that study in the analysis. Error bars represent 95% confidence intervals of the effect size.

Figure 3

Significant moderators of stress effects on working memory. As (A) the percent of male participants, (B) the delay between stress onset and working memory testing, (C) study precision, and (D) working memory load increased, stress effects on working memory became more impairing. However, only (C) study precision—the reduction of confounds related to assessment of acute stress and/or working memory—and (D) working memory load remained significant when accounting for covariance of other moderators.

Figure 4

Effect of stress effect on inhibition. Acute stress did not influence inhibition overall. Size of the square indicates the relative weight assigned to that study in the analysis. Error bars represent 95% confidence intervals of the effect size.

Figure 5

Inhibition type significant moderates stress effects on inhibition. Stress significantly impaired cognitive inhibition (i.e., interference control) but enhanced response inhibition.

Figure 6

Effect of stress effect on cognitive flexibility. Acute stress significantly impaired cognitive flexibility. Size of the square indicates the relative weight assigned to that study in the analysis. Error bars represent 95% confidence intervals of the effect size.

Figure 7

Study precision significantly moderated stress effects on cognitive flexibility. As study precision improved, stress effects on cognitive flexibility became more impairing.

Figure 8

Comparison of effects of acute stress and cortisol administration on core executive functions. (A) The time-dependent effects of acute stress on working memory significantly differed from the time-dependent effects of cortisol on working memory. (B) The effects of acute stress on cognitive inhibition (i.e., interference control) significantly differed from the effects of cortisol administration on cognitive inhibition; no significant difference was observed in response inhibition, although stress effects tended to be larger. (C) The effects of acute stress on cognitive flexibility were marginally more impairing than the effects of cortisol administration on cognitive flexibility.