Background: Nicotine is a cholinergic agonist that acts, not only post-synaptically, but also releases pre-synaptic acetylcholine, and in animal models has been shown to reverse spatial memory decline in rats with lesion in the medial septal nucleus and to show recovery on memory in aged monkeys. Nicotine also has effects on other transmitters like serotonin (5HT), dopamine, or GABA. On the other hand, because nicotine has serious adverse effects, especially concerning cardiovascular risks in elderly people, and also on sleep and behavior, there are several important reasons to conduct a systematic review to assess the clinical efficacy and safety of nicotine in patients with AD.
Objectives: The aim of this review is to determine whether there is evidence of beneficial effect, and to assess its safety profile, when nicotine is used for Alzheimer's disease.
Search strategy: The Cochrane Controlled Trials Register (Issue 2, 99) was searched using the terms nicotin* and alzheimer*. Three references to trials were deemed suitable for inclusion but are awaiting consideration while the investigators are contacted.
Selection criteria: All unconfounded, double-blind, randomized trials in which treatment with nicotine patches or administration of nicotine intravenously was administered for more than a day and compared to placebo in people with Alzheimer's disease.
Data collection and analysis: As no trials were suitable for inclusion, no data have been extracted or pooled in a meta-analysis. One trial is awaiting consideration, and if included in an update of this review, any available data will be incorporated.
Main results: The poor quality of the trials did not allow any synthesis of results across studies. However, the data available in trials considered are compatible with nicotine producing harm, no change or improvement.
Reviewer's conclusions: This review is not able to provide reliable evidence that nicotine is a useful treatment for Alzheimer's disease.