Noradrenaline and cortisol exert differential effects on working memory and risk-taking behaviour in military personnel

RATIONALE: Military personnel are exposed to bouts of acute stress during their careers, in which cognitive processes associated with decision-making might simultaneously suffer. Currently, it is still unclear how hormones and neurotransmitters involved in the acute stress response specifically affect these decision-making subprocesses, particularly in the military. OBJECTIVES: We aimed to expose military personnel to pharmacological stress, in which noradrenaline and/or cortisol activity was stimulated. Next, decision-making subprocesses (i.e. working memory, impulse control and risk-taking) were assessed. METHODS: A sample of 100 Dutch military personnel were recruited. Noradrenaline and/or cortisol activity was stimulated through oral administration of yohimbine and hydrocortisone, respectively. Decision-making subprocesses were assessed through computerised tasks. RESULTS: Induction of stress was confirmed through psychophysiological measures. Working memory seemed subtly affected by stress, as heightened noradrenaline slowed recall while cortisol accelerated it. Inhibition was unaffected by acute stress. Risk-taking was enhanced solely by noradrenaline, contrasting earlier research positing cortisol as a predictor of amplified risk-taking in civilians. CONCLUSIONS: Our findings contribute to the existing literature of the effects of acute stress on cognitive processes associated with decision-making, emphasising intricacies of the effects of specific stress hormones and neurotransmitters. Future research is needed to further identify these differential intricacies on cognitive processes, keeping potential differences between demographic subgroups in mind.