Differential CNS effects of diazepam in elderly adults

The present study examines the effects of 0.07, 0.14 and 0.21 mg/kg of diazepam on the performance of several cognitive and neuromotor tasks, including wheel tracking, digit symbol substitution and standing steadiness. The drug or placebo was administered at 3-week intervals to healthy elderly men (N = 8) and women (N = 8). Both medium and high doses significantly impaired performance on the cognitive tasks, whereas only the latter dose induced similar impairment effects on the neuromotor tasks. Wheel tracking and standing steadiness displayed rapid onset and offset of the drug effect, while acute tolerance developed at a considerably slower rate on the digit symbol substitution tasks. Specifically, the subjects continued to show poorer cognitive performance for over 3 hours after dosing, but were no longer impaired on the basically neuromotor skills at 3 hours.