Most mental-health problems have a number of different causes both environmental and genetic and Alzheimer's disease is no exception. A Swiss study of 4.7 million people using census data from 1990 and 2000 and mortality data from 2000-2005 has added another environmental factor to the list in the form of high-voltage power cables. Those people who lived within 50m of a power line were 24% more likely to die of Alzheimer's and the longer they lived there the greater the risk. After 5 years the risk rose by 51%, after a decade 78% and after 15 years the risk doubled. However, in Switzerland at least, it is estimated that only 0.3% of the population live so close to a power line at any one time.
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