Sir, - The Irish Times carried a report titled "A puff a day helps keep dementia at bay" in the world news section on October 24th. The report discussed the proposal, by a group at Houston's Baylor College of Medicine, and published in Nature, that the drug, nicotine, enhances the effects of the neurotransmitter acetylcholine in rats brains, thus stimulating nerve impulse transmission in the hippocampus area of the brain. Acetylcholine is the main neurotransmitter that is deficient from the hippocampus in Alzheimer's disease.
Based on these findings, it is possible that nicotine may play a role in delaying the onset of Alzheimer's disease, but it is misleading to conclude that cigarette smoking keeps dementia at bay. The side effects of cigarette smoking, including heart disease, lung cancer, peripheral vascular disease and strokes far outweigh any possible benefit accrued by smoking. The researchers in Texas do not advocate cigarette smoking as a method of preventing the onset of Alzheimer's disease. Their study was performed in a laboratory setting, and nicotine was applied directly to the hippocampus in the rat brain.
The second most common cause of dementia, after Alzheimer's disease, is vascular dementia, in which mini strokes damage areas of the brain controlling memory. Smoking is one of the main risk factors for vascular dementia, a disease as devastating and disabling as Alzheimer's disease.
The only truth in stating that cigarette smoking may prevent dementia is that smokers have a far greater chance of dying from the effects of smoking before they develop Alzheimer's disease.
Yours, etc.,
Mercer's Institute for
Research on Ageing,
St. James's Hospital,
Dublin 8.