Effects of amisulpride on emotional memory using a dual-process model in healthy male volunteers

Memory dysfunction occurs in a number of neuropsychiatric disorders. Therapeutic psychopharmacological agents may exacerbate such memory impairment. Detailed characterisation of drug-induced memory impairment is therefore important. We recently showed that the D(2)/D(3) antagonist amisulpride quantitatively impairs emotional memory in a randomised placebo-controlled study of 33 healthy volunteers. Current evidence suggests that two qualitatively different processes (recollection and familiarity) contribute to recognition memory and can be investigated using a Dual-Process Signal Detection model. Using such a model, we found that amisulpride levels at encoding were significantly inversely correlated with recollection estimates for emotional but not neutral stimuli or familiarity estimates in healthy male volunteers. This suggests that dopamine antagonism at encoding preferentially impairs the recollection component of emotional memory, relative to the familiarity component. This was supported by receiver operating characteristic analysis. We also found a significantly increased false recognition rate, associated with significantly shorter reaction times for emotional but not neutral stimuli in the amisulpride group. These findings have important implications for our understanding of recognition memory processes, as well as the interpretation of neuropsychological findings in medicated patients.