1. ¹Department of Psychiatry, University of Colorado School of Medicine, Denver, CO, USA
2. ²Department of Biometrics and Statistics, University of Colorado School of Medicine, Denver, CO, USA
3. ³Denver Veterans Affairs Medical Center, Denver, CO, USA

Correspondence: JG Harris, Department of Psychiatry, C268-71, University of Colorado Health Sciences Center, Denver, CO 80262, USA. Tel: +1 303 315 4610; Fax: +1 303 315 5347; E-mail: josette.harris@uchsc.edu

Received 23 August 2003; Revised 28 December 2003; Accepted 29 January 2004; Published online 12 May 2004.

Abstract

Several lines of evidence suggest a pathophysiological role for nicotinic receptors in schizophrenia. Activation by nicotine alters physiological dysfunctions, such as eye movement and sensory gating abnormalities, but effects on neuropsychological performance are just beginning to be investigated. Nicotine-induced desensitization and the well-known tachyphylaxis of nicotinic receptors may confound such efforts. In all, 20 schizophrenics, 10 smokers, and 10 nonsmokers were assessed following the administration of nicotine gum and placebo gum. The Repeatable Battery for the Assessment of Neuropsychological Status was administered. Nicotine affected only the Attention Index; there were no effects on learning and memory, language, or visuospatial/constructional abilities. Attentional function was increased in nonsmokers, but decreased in nicotine-abstinent smokers after nicotine administration. The effects of nicotine in schizophrenia do not extend to all areas of cognition. Effects on attention may be severely limited by tachyphylaxis, such that decremented performance occurs in smokers, while modest effects may be achieved in nonsmokers.