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DDT exposure potential risk factor for Alzheimer's

By Quinn Eastman

Story Photo

US soldiers demonstrate DDT hand-spraying equipment.

DDT was used extensively after World War II in agriculture and for mosquito control until it was banned in the US in 1972.

Now researchers have found that patients with Alzheimer's disease have significantly higher levels of DDE, the long-lasting metabolite of the pesticide DDT, in their blood than healthy people.

Researchers found that DDE levels were almost four times higher in serum samples from Alzheimer's patients than in controls. DDE levels in the highest third of the sample range increased the risk of Alzheimer's by a factor of four, according to a study published in JAMA Neurology. "This is one of the first studies identifying a strong environmental risk factor for Alzheimer's disease," says coauthor Allan Levey, director of Emory's Alzheimer's Disease Research Center and Betty Gage Holland Chair of Neurology. "The magnitude of the effect is strikingly large—it is comparable in size to the most common genetic risk factor for late-onset Alzheimer's."

The researchers identified a plausible mechanism for DDE's effects. Cultured neural cells exposed to high levels of the pesticide produced more of a protein that is a precursor to beta-amyloid, the main component of plaques found in the brains of Alzheimer's patients.

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