A comparison of the effects of olanzapine, haloperidol and placebo on cognitive and psychomotor functions in healthy elderly volunteers

The cognitive and psychomotor effects of olanzapine (3 mg) were compared wi th haloperidol (3 mg) and placebo in a double-blind, cross-over study. Four teen healthy elderly volunteers (> 65 years) were randomized to receive onc e daily medication for 4 days with a 16-day interval between treatment peri ods. Assessments of attention, memory and motor control were made prior to dosing on each day, at 2, 4, 6 and 8 h after dosing on days 1 and 4, and at 24 and 48 h following the last dose. On day 1, detectable impairment was o bserved at all time points in both groups. On day 4, haloperidol treated su bjects showed increased impairment compared with day 1 and this was sustain ed throughout the 48 h of testing. Olanzapine treated subjects showed reduc ed day 4 deficit (compared with day 1), with no significant difference from placebo beyond 6 h post dose. These results suggest that both haloperidol and olanzapine have a measurable initial effect on cognitive and psychomoto r function in elderly volunteers. However, acute effects associated with ol anzapine decrease with repeated dosing and show substantial adaptation with in 4 days. In contrast, effects seen with haloperidol are sustained and inc rease with repeated dosing over the same period.