The pesticide DDT has been linked to a decrease in bird health in the past; but researchers now believe it could also contribute to Alzheimer's risk in humans.
DDT has been banned in the U.S. since 1972, but is still used in a number of countries, a Rutgers Biomedical and Health Sciences news release reported. The chemical is used to control insect populations and insect-borne illnesses.
The new research suggests DDE ("the chemical compound left when DDT breaks down") levels were higher in the blood of those suffering from late-onset Alzheimer's.
"I think these results demonstrate that more attention should be focused on potential environmental contributors and their interaction with genetic susceptibility," 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). "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."
Levels of these pesticides have decreased significantly over the past few decades but traces are still found in between 75 and 80 percent of all blood samples collected by the Centers for Disease Control and Prevention (CDC). The substance can take decades to break down naturally; it could also still be present on imported produce and in fish from polluted water sources.
Seventy-four of the 86 Alzheimer's patients included in the study (whose average age was 74) had DDE blood levels about four times higher than the 79 people studied who did not have Alzheimer's disease.
Patients with a form of the ApoE gene which has been linked to Alzheimer's as well as high DDE levels showed even more cognitive impairment than those without the genetic signature.
DDT and DDE were also linked with brain plaque, which is believed to be correlated with Alzheimer's. "Sticky amyloid proteins" can form in regions of the brain connected to memory and thinking which could contribute to the disease's progression. The finding could mean DDT exposure directly contributes to plaque formation.
"We need to conduct further research to determine whether this occurs and how the chemical compound interacts with the ApoE4 gene" Richardson said.
Alzheimer's is believed to be caused by a number of factors including genetics and lifestyle.
"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 said. "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."
