Long-term outcomes of memory retrieval under stress

Previous studies have found impairing effects of stress hormones on memory retrieval. So far, it is unknown whether these impairments are temporary, persistent throughout time, or whether the strength of the memory trace changes after retrieval because of the effects of stress hormones on memory processes during retrieval. In the present study, delayed cued recall (6 months after initial learning) was compared between male participants who had retrieved previously learned word pairs during stress or a control condition. Retrieval (with or without stress) had taken place either 1 day or 5 weeks after initial encoding. The group that had retrieved words under stress 5 weeks after encoding performed worse on long-term recall than the comparable control group. However, when words were retrieved under stress 1 day after encoding, no long-term effect was found, although performance at 6 months in relation to performance under stress was slightly increased compared to the control group. These results support previous findings in animals that stress may affect memory during reactivation. It further suggests that time intervals between encoding and reactivation may play an important role.