No interaction between rivastigmine and citalopram on memory and novelty processing in healthy human volunteers

Background: Animal literature suggests an interaction between acetylcholine and serotonin on cognitive functions. Aims: The aim of the current study was to assess whether both neurotransmitters interact during memory and novelty processing in humans. Methods: We tested the interaction between acetylcholine and serotonin on cognitive functions in healthy volunteers by means of treatment with rivastigmine and citalopram, respectively. Results: The main result of the study showed that during the verbal learning task participants significantly recalled fewer words after citalopram treatment than after rivastigmine or placebo during both the immediate and delayed recall tasks. Rivastigmine was not able to reverse the impairing effect of citalopram. Conclusions: This finding is in line with previous studies in which we manipulated acetylcholine and serotonin in different manners. Taken together, these studies in humans do not support the notion from animal studies that these two neurotransmitters interact on cognitive functions.