Exposure to stress attenuates fear retrieval in healthy men

The stress hormone cortisol reduces retrieval of emotional memories, which has been suggested to support the treatment of psychiatric disorders characterized by exaggerated fear-related memories. Indeed, studies in patients with anxiety disorders have indicated that the success of exposure therapy can be enhanced with accompanying cortisol administration. Fear renewal refers to the clinically relevant phenomenon that successfully extinguished fear can return after a context change. It remains to be investigated whether the effects of stress hormones on fear retrieval also generalize across different contexts. Healthy men were exposed to a fear renewal design with fear acquisition in context A and extinction in context B. Pictures of rooms served as contexts, coloured lights were introduced as conditioned stimuli (CS), and an electrical stimulation served as the unconditioned stimulus (UCS). On the next day, participants were randomly assigned to a stress (Socially Evaluated Cold Pressor Test) or a control condition (n=20 each). We tested for fear retrieval in contexts A and B during peak cortisol concentrations after stress induction. Overall, a context×stress interaction occurred, revealing that stress attenuated skin conductance responses in the extinction context B. Stress also reduced UCS expectancy in context B. Additionally, stress abolished the renewal effect (differentiation between CS in context A) at the electrodermal level. These results demonstrate a decreased return of fear after acute exposure to stress. Stress interferes with the retrieval of the original fear memory which in turn affects extinction responding. Thus, acute stress reduces rather than promotes the return of fear.