Abstract

THE EFFECTS OF NOISE, CLONIDINE, AND IDAZOXAN ON SUBJECTIVE ALERTNESS

Andrew P. Smith, PhD*

ABSTRACT

Background: The antihypertensive α2-adrenergic receptor agonist, Clonidine, has been shown to impair sustained attention and to slow saccadic eye movements. Noise and the selective antagonist, Idazoxan, reverse clonidine-induced impairment of sustained attention. The present analyses examined the effects of Clonidine on subjective alertness and investigated whether the effects of Clonidine were blocked by Idazoxan and modified by noise. Method: Seventy-six healthy male participants were administered either Clonidine 200μg, Idazoxan 40mg, the combination of Clonidine 200μg plus Idazoxan 40mg, or a placebo in a double-blind, parallel-group design. Half of the participants, balanced across drug treatment groups, were also exposed to 80dB white noise via headphones. At baseline and on three occasions after drug administration, participants rated their alertness. Results: Clonidine significantly decreased alertness, and this effect was reversed by Idazoxan and initially noise. Prolonged exposure to noise did not have an alerting effect in the clonidine condition. Conclusion: Clonidine reduced alertness, and this effect was blocked by Idazoxan and reversed by initial but not pronged exposure to noise.

Keywords: Central Noradrenaline, Noise, Clonidine, Idazoxan, Alertness.