Effect of zopiclone and temazepam on sleep EEG parameters, psychomotor and memory functions in healthy elderly volunteers

Rationale: The increased prevalence of sleep disturbance in old age is accompanied by a higher prescription rate of hypnotics, predominantly benzodiazepines in the elderly. In young volunteers zopiclone exerts a beneficial effect on sleep continuity without suppression of SWS and REM sleep; psychomotor performance and vigilance seemed to be less impaired than under classical benzoediazepines. Objective: The present study investigates the effects of zopiclone on sleep EEG and cognitive performance in comparison to temazepam and placebo in the elderly population. Methods: Single oral doses of zopiclone (7.5 mg), temazepam (20 mg) and placebo were administered in a randomized double-blind, completely counterbalanced cross-over design to 12 healthy elderly men and women (65.9+/-3.6 years, range 60-70 years). On each of the 3 study nights a sleep EEG was registered from 10 p.m. to 6.30 a.m. and cognitive performance tests were applied at 8 p.m., 2 a.m. (when subjects were awake for 30 min), 7 a.m. and 9 a.In. Results: After zopiclone treatment, sleep continuity had significantly improved and sleep stage 4 was increased compared to temazepam and placebo. In addition, both active substances significantly reduced REM density. Neither active compound substantially altered psychomotor and memory performance. Conclusions: Zopiclone and temazepam can be considered as effective hypnotics in elderly subjects when administered in that dosage. The superiority of zopiclone on sleep architecture may be related to a more specific action of zopiclone at the GABA-A benzodiazepine receptor complex. The suppression of REM density by both compounds and their subtle effects on cognition may reflect a GABAergic mediated reduction of cholinergic neurotransmission.