Study: Link Found Between DDT Exposure and Alzheimer’s Disease

February 25, 2014- For more than 40 years scientists have known of the harm that the synthetic pesticide DDT causes in bird habitats and the environment. Now comes news that the chemical compound DDE, created as DDT breaks down, was higher in the blood of late-onset Alzheimer's disease patients as compared to a control group who did not have Alzheimer's disease.

In a recent article on DDT pesticide exposure links to Alzheimer's disease, ScienceDaily.com reported on results by Rutgers University, published in JAMA Neurology. The study calls for more research into how DDT and DDE may become triggers for neurodegenerative diseases such as Alzheimer's in some people, particularly those over the age of 60.

Here are some of the highlights from the ScienceDaily article:

- First introduced in WWII, DDT was used in the U.S. to control insects in crops and livestock as well as to combat insect-borne diseases such as malaria. Its use was banned in America in 1972, but it is still being sold and applied throughout the world.

- ScienceDaily quoted Jason R. Richardson, associate professor in the Department of Environmental and Occupational Medicine at Robert Wood Johnson Medical School and a member of the Environmental and Occupational Health Sciences Institute (EOHSI). Richardson said, "I think these results demonstrate that more attention should be focused on potential environmental contributors and their interaction with genetic … Our data may help identify those that are at risk for Alzheimer's disease and could potentially lead to earlier diagnosis and an improved outcome."

- Scientists say that DDT can take decades to break down in the environment. Over time DDT and DDE levels have significantly declined in the U.S. and yet the Centers for Disease Control and Prevention finds the toxic pesticide in 75-80% of blood samples collected. Exposure to the pesticide includes consuming imported grains, fruits and vegetables as well as eating fish from contaminated waterways from locales where DDT is still being used.

- The Rutgers study was conducted in coordination with the Alzheimer's Disease Centers at both Emory University and the Texas Southwestern Medical School. ScienceDaily writes, "74 out of the 86 Alzheimer's patients involved — whose average age was 74 — had DDE blood levels almost four times higher than the 79 people in the control group who did not have Alzheimer's disease."

- Moreover, the researchers found that patients with the ApoE4 version of the ApoE gene shoed greatly increased risk of developing Alzheimer's, and high blood levels of DDE showed even more severe cognitive impairment than participants without the risk gene.

- Studies of brain cells found that DDT and DDE increased the levels of a protein associated with sticky amyloid proteins, commonly called plaques, which form in areas of the brain associated with thinking, learning and memory. As Alzheimer's progresses, these plaques break off and form clumps.

- Richardson tells ScienceDaily, "This new research is important because it suggests that DDT and DDE may directly contribute to the process of plaque development [so] we need to conduct further research to determine whether this occurs and how the chemical compound interacts with the ApoE4 gene."

- The exact cause of Alzheimer's disease, which strikes five million Americans now, is not yet known. Many millions more are expected to become stricken by what is currently believed to be a combination of genetic, environmental and lifestyle factors. Up to this point in time, much of the Alzheimer's research has been focused on genetics.

- "This study demonstrates that there are additional contributors to Alzheimer's disease that must be examined and that may help identify those at risk of developing Alzheimer's," Richardson tells ScienceDaily. "It is important because when it comes to diagnosing and treating this and other neurodegenerative diseases, the earlier someone is diagnosed, the more options there may be available."

Read the full ScienceDaily post here.

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