In this double-blind, placebo controlled, four-way cross-over trial in 16 healthy elderly volunteers, the acute effects of haloperidol 2 mg, amisulpride 50 mg and 200 mg, were assessed on a range of tests of cognitive function. On each study day, cognitive performance was assessed prior to dosing and at 2, 4, 6, 9, 12 and 24 h after dosing with the following tests from the Cognitive Drug Research computerized assessment system: simple reaction time, digit vigilance task, choice reaction time, visual tracking, Critical Flicker Fusion, body sway, numeric working memory, immediate and delayed word recall, word recognition and self-ratings of mood and alertness. Haloperidol showed a general tendency to impair performance, and although this did not reach significance compared to placebo, for two tasks there were significant impairments with haloperidol compared to amisulpride. Amisulpride 50 mg and 200 mg, was not associated with impairment. In fact, there was some suggestion of improvement over placebo on three measures. The timings of assessment were appropriate for the study compounds. Furthermore, in a recent study in which a smaller number of elderly volunteers was tested on the same cognitive assessment system, a clear profile of acute impairments of haloperidol 3 mg, was identified. This indicates that haloperidol 2 mg, is not a sufficient dose to affect cognitive function in the elderly, supporting the general absence of effects with this dose in the young. Thus, the general absence of cognitive impairments with amisulpride at the doses used in this study suggests that this compound does not impair cognitive function in the elderly.
