The effects of noradrenergic re-uptake inhibition on memory encoding in man.

RATIONALE

Animal and human evidence implicate the central noradrenergic system in the process of memory modulation for emotional material. Blockade of the beta-adrenergic system in humans has been shown to result in decreased recall and recognition memory performance, relative to placebo, for the emotional elements of a series of slides accompanied by a narrative. Stimulation of the noradrenergic system with yohimbine has also been shown to result in increased recall and recognition performance relative to placebo for the same stimulus materials.

OBJECTIVES

The present study tested the hypothesis that stimulating the central noradrenergic system using the new noradrenaline re-uptake inhibitor reboxetine would result in a dose-dependent enhancement of memory for emotional material in man.

METHODS

The central noradrenergic system was manipulated using reboxetine in a double-blind, randomised between-group, placebo-controlled design with 36 healthy adult subjects in each of three groups (placebo, 4 and 8 mg reboxetine). Free recall and recognition memory performance were assessed in a 'surprise' memory test following a 7-day interval.

RESULTS

We found no memory enhancing effect of reboxetine. In contrast we observed a dose-dependent effect on memory opposite to the predicted direction. There were no significant differences between groups in self-rated stress and arousal scores or self-rated emotional reactions to the stimuli. All groups showed the expected increased memory performance for the middle 'emotive' phase of the story.

CONCLUSION

Selective stimulation of the central noradrenergic system at encoding did not result in enhanced long-term memory for emotional material in man.