A new study has found a strong link between a once popular pesticide and patients with Alzheimer's disease.

A team of researchers from Rutgers and Emory Universities tested the blood levels of 86 patients with Alzheimer's disease and compared the results with 79 people of a similar age and background who did not have the illness.

The results showed those with Alzheimer's had 3.8 times the level of DDE - a byproduct of DDT - when compared with patients who did not have the disease.

Four decades ago, DDT was the pesticide of choice for commercial farmers around the world. It was also used to control malaria at the end of World War II. It was banned in 1972, after alarms were raised about the pesticide's potential impact on human and environmental health.

But more than forty years later, DDT still lingers in the environment - and in human bodies where it is broken down into DDE. And this latest study shows that patients with high levels of DDE may be more likely to develop Alzheimer's than those with lower DDE blood levels.

Researchers think that DDE might contribute to the development of plaques in the brain which in turn cause brain cells to die.

Dr Jason Richardson, a lead author of the study commented, "We are still being exposed to these chemicals in the United States, both because we get food products from other countries and because DDE persists in the environment for a long time."

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