Pesticide Byproduct Linked to Alzheimer's Disease

By Kelly Young

A byproduct of the banned insecticide dichlorodiphenyltrichloroethane (DDT) is associated with increased risk for Alzheimer disease, according to a small study in JAMA Neurology.

Researchers assessed serum levels of the metabolite, known as dichlorodiphenyldichloroethylene (DDE), in roughly 80 controls and 80 people with Alzheimer's. Patients with serum levels in the highest tertile were over three times more likely to have Alzheimer's than patients in the bottom tertile.

Alzheimer's severity increased with higher DDE levels. In addition, the likelihood of more severe impairment was higher when patients also carried an APOE allele known to increase Alzheimer's risk.

DDT was banned in the U.S. in 1972, but the researchers note that it has a long half-life. In addition, DDT could make its way into the U.S. on imported food.

Editorialists, noting several weaknesses in the study, write: "These conclusions should be considered as preliminary until there is independent confirmation in other populations."