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Study links smoking to Alzheimer's disease Copyright © 1998 Nando.net/Copyright © 1998 The Associated Press LONDON (June 18, 1998 http://www.nando.net) -- Smokers are twice more likely than lifetime nonsmokers to develop Alzheimer's disease and other forms of dementia, a study published Friday suggests. Results of other studies differ on whether smoking increases the risk of developing Alzheimer's or somehow protects against it. But scientists say the latest study by researchers at Erasmus University in the Netherlands is important because it is the largest to investigate the link -- and the first major project to have evaluated people before they develop brain disease. Dr. Anthony Mann, an old-age psychiatrist and professor of epidemiology at the Institute of Psychiatry in London, called the findings powerful." "They are the first to do a prospective study and it's the largest to show a positive link," said Mann, who wasn't involved in the research. "It's the best we've had." The study in Britain's The Lancet medical journal followed 6,870 men and women ages 55 and older living in a suburb of Rotterdam. It found that smokers were 2.2 times more likely to develop dementia of any kind and had a risk for Alzheimer's disease that was 2.3 times higher than those who had never smoked cigarettes. Alzheimer's disease is the most common form of dementia, estimated to afflict nearly 18 million people worldwide, or 3 percent of people over the age of 60, according to the nonprofit Alzheimer's Disease International. Unlike previous studies, none of the people in the Rotterdam study had dementia when first examined. They were asked about their smoking habits and divided into smokers, former smokers and those who had never smoked. Two years later, 146 study participants had developed dementia and 105 of those had been diagnosed with Alzheimer's disease. Factors such as age, sex, education and alcohol intake were taken into account in calculating the risk. Within a random sample of the whole group, the researchers also examined the effect of smoking on people who carried a gene believed to increase the risk of Alzheimer's disease. They found that despite the overall finding that smoking doubled the risk of developing the degenerative disease, smokers who carried the gene actually were no more likely to develop Alzheimer's than nonsmokers. But smokers who did not carry the gene were found to be four times more likely to develop the disease than nonsmokers, the study said. "It seems that if you have the gene, you're better off if you smoke," said Dr. Monique Breteler, who headed the research. Scientists are unsure exactly how smoking might contribute to Alzheimer's. Still, Mann said, "It takes forward that things that put you at risk for vascular disease put you at risk for dementia in general." By EMMA ROSS, Associated Press Writer -- Judith Richards, London, Ontario, Canada [log in to unmask]