Automatic attentional shifts induced by a noradrenergic drug in Alzheimer's disease: evidence from evoked potentials

Prior research showed that attentional deficits are observed in Alzheimer's disease (AD), These deficits can further impair other cognitive processes. The present experiment was designed to study the shifts in attention induc ed by a noradrenergic drug (S 12024-2) through their electrophysiological c orrelates in 12 outpatients with mild AD, using an auditory oddball paradig m. The P3a component, known to be related to automatic attentional processi ng, was increased by the drug, whereas no changes occurred either in PN or in P3b, which are considered to reflect conscious processing. These results point to an involvement of the noradrenergic system in the modulation of a utomatic attentional processing, and provide evidence for weakening of the orienting reflex in AD, due to a possible noradrenergic deficit in patients with mild AD. (C) 1999 Elsevier Science B.V. All rights reserved.