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Pesticide Levels and Risk for Alzheimer Disease (2014-01-28)

Although the cause of Alzheimer disease remains unknown, researchers believe genetic, lifestyle, and environmental factors influence a person’s risk of developing the late-onset form of the disease, the disorder’s most common form. Now research appearing in JAMA Neurology may shed light on a possible environmental risk factor, exposure to DDE (dichlorodiphenyldichloroethylene), a byproduct of the pesticide DDT, (dichlorodiphenyltrichloroethane).



Limited epidemiological studies suggest that occupational pesticide exposures are associated with Alzheimer Disease. Previously, researchers reported that serum levels of DDE, the metabolite of the pesticide DDT, were elevated in a small number of patients with Alzheimer Disease.

To evaluate the association between serum levels of DDE and Alzheimer Disease and whether the apolipoprotein E (APOE) genotype modifies the association, researchers analized data in a case-control study consisting of existing samples from patients with Alzheimer Disease and control participants from the Emory University Alzheimer’s Disease Research Center and the University of Texas Southwestern Medical School’s Alzheimer’s Disease Center. Serum levels of DDE were measured in 79 control and 86 Alzheimer Disease cases.

Levels of DDE were 3.8-fold higher in the serum of those with Alzheimer Disease when compared with control participants.

Elevated serum DDE levels are associated with an increased risk for AD and carriers of an APOE4 ε4 allele may be more susceptible to the effects of DDE. Both DDT and DDE increase amyloid precursor protein levels, providing mechanistic plausibility for the association of DDE exposure with AD. Identifying people who have elevated levels of DDE and carry an APOE ε4 allele may lead to early identification of some cases of AD.

Jason R. Richardson, PhD, of the Rutgers Robert Wood Johnson Medical School and Environmental and Occupational Health Sciences Institute, Piscataway, New Jersey, in 2009 published a study in the then Archives of Neurology looking at pesticide chemicals and Parkinson disease. While doing that, Richardson had a control group but thought to add another neurodegenerative disease. So he took 20 samples from patients with Alzheimer disease and he found higher levels of DDE in the Alzheimer’s samples. It was intriguing, but you don’t want to get too excited about 20 samples. So he cobbled together some funds and now we’ve confirmed that original sample.

DDE has a long half-life, so especially meat, fish, and diary can harbor these types of chemicals.

For more information
Elevated Serum Pesticide Levels and Risk for Alzheimer Disease

Elevated Serum Pesticide Levels and Risk of Parkinson Disease

Pesticides and Parkinson's: Researchers uncover further proof of a link

Exposure to pesticides or solvents and risk of Parkinson disease