Four-week nicotine skin patch treatment effects on cognitive performance in Alzheimer's disease.
RATIONALE: Acute nicotine injections have been found to improve attentional performance in patients with Alzheimer's disease (AD), but little is known about chronic nicotine effects. OBJECTIVE: The present study was undertaken to evaluate the clinical and neuropsychological effects of chronic transdermal nicotine in Alzheimer's disease subjects over a 4-week period. METHODS: The double-blind, placebo controlled, cross-over study consisted of two 4-week periods separated by a 2-week washout period. Patients wore the nicotine patch (Nicotrol) for 16 h a day at the following doses: 5 mg/day during week 1, 10 mg/day during weeks 2 and 3 and 5 mg/day during week 4. The eight subjects had mild to moderate AD and were otherwise healthy. RESULTS: Nicotine significantly improved attentional performance as measured by the Conners' continuous performance test (CPT). There was a significant reduction in errors of omission on the CPT which continued throughout the period of chronic nicotine administration. The variability of hit reaction time (reaction time for correct responses) on the CPT was also significantly reduced by chronic nicotine. Nicotine did not improve performance on other tests measuring motor and memory function. CONCLUSIONS: The sustained improvement in attention found in this study with nicotine dermal patches is encouraging. However, the lack of detected effects of nicotine treatment on other cognitive and behavioral domains in this study leaves questions concerning the clinical impact of nicotinic treatment in Alzheimer's disease. The modest size of this study limited statistical power which may have been needed to detect more subtle but clinically significant cognitive effects. Higher doses of nicotine, other nicotinic ligands or combination treatment of nicotine with other therapies may be efficacious for producing broader therapeutic effects.
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