Serotonin, noradrenaline and cognitive function: a preliminary investigation of the acute pharmacodynamic effects of a serotonin versus a serotonin and noradrenaline reuptake inhibitor

Comparisons of the behavioural side-effect profiles of antidepressants that inhibit either serotonin or both serotonin and noradrenaline reuptake, may reveal differences in cognitive and psychomotor functions, which may be attributed to their relative pharmacological selectivity for potentiating monoamine neurotransmission in the central nervous system. The aim of the present study was to determine the acute pharmacodynamic effects of citalopram and venlafaxine, on cognitive and psychomotor performance. Nine healthy male volunteers received a single clinical dose of citalopram, venlafaxine or amitriptyline (positive control) in a double-blind placebo-controlled design. Cognitive and psychomotor tests and a subjective measure of sedation were examined before and 1, 2 and 4 hours after drug administration. Citalopram improved psychomotor responses to sensory stimuli and sustained attention, with significant decreases in movement times of the choice reaction time test and an increase in critical flicker fusion threshold. Venlafaxine did not affect performances on any of the cognitive or psychomotor tests examined. Differences may be related to relative potencies of the compounds for monoamine reuptake inhibition.