Associations between endogenous cortisol levels and emotional memory in young women: influence of encoding instructions.

The stress hormone cortisol is known to influence memory. Elevated cortisol levels as a consequence of stress or as a consequence of cortisol administration have been repeatedly shown to enhance encoding and consolidation of (emotional) memory. Whether similar associations exist between basal cortisol levels and emotional memory remains to be established. The present study therefore evaluated if resting cortisol levels are correlated with memory for emotionally arousing and neutral pictures in a sample of young healthy females (n = 56). A second aim of the study was to explore if the relationship between basal cortisol levels and memory might be modulated by encoding instructions (intentional vs. incidental encoding). A significant positive correlation between basal salivary cortisol levels and memory for emotionally arousing pictures in a 24 h delayed free recall test was found. Further analyses revealed that this association only occurred in the group receiving intentional encoding instructions. Results indicate that basal cortisol levels, similarly to stress induced cortisol levels, are associated with emotional memory formation. Moreover this effect seems to be modulated by encoding instructions, suggesting a role of focussed attention or arousal induced by testing in this relationship.