Once considered to be a miraculous ally in the fight to eradicate malaria, scientists have now linked the pesticide, DDT (dichlorodiphenyltrichloroethane), to one of the most feared diseases of our time: Alzheimer’s.
The blood levels of DDE (a by-product of DDT break down) were virtually four times greater in individuals with Alzheimer’s, when compared to individuals without the disease, according to a study published in the most recent issue of JAMA Neurology.
The majority of the elderly participants in the study showed signs of DDT exposure—an unsurprising finding given the widespread use of the chemical during the years following World War II.
Perhaps the most notorious pest control agent ever, DDT is known for its ability to pervade food and water sources, and has been connected with a host of health problems, including miscarriages, cancer, liver damage, nervous system dysfunction, and male fertility issues.
The 1962 book, Silent Spring, written by American biologist, Rachel Carson, is credited with igniting the movement that eventually led to the nationwide ban of DDT by the Environmental Protection Agency in 1972, and the worldwide moratorium handed down by the Stockholm Convention on Persistent Organic Pollutants in 2001. Yet, despite the passing of four decades since its prohibition in the U.S., traces of DDT are still found in environmental, food and human blood samples.
This most recent discovery doesn’t prove that DDT exposure causes Alzheimer’s, but study author Jason Richardson, an associate professor in the Department of Environmental and Occupational Medicine at Robert Wood Johnson Medical School at Rutgers University, says the results make a strong case for adding the dreaded disease to the ever-growing list of DDT-related medical concerns, particularly for people with the ApoE4 allele, an expression of the ApoE gene said to increase an individual’s risk for developing Alzheimer’s disease.
A piece in the genetic puzzle of Alzheimer‘s
Medical experts have long questioned why individuals with the ApoE4 gene appear more likely to get Alzheimer’s disease.
Previous research indicates that this particular genetic component may interfere with the destruction of amyloid-beta, a by-product of brain functioning found in large quantities in the brains of most Alzheimer’s patients, and lead to increased susceptibility to neuron-damaging inflammation.
Richardson and his colleagues determined that the presence of high levels of DDT and DDE led to more profound cognitive impairment and greater amounts of amyloid-beta protein deposition in people with ApoE4. While further research needs to be done to uncover the specifics of this link, Richardson feels these initial conclusions add weight to the theory that Alzheimer’s is caused by a complex confluence of factors, both environmental and biological.
Scientists still struggle to pinpoint the precise elements that contribute to the development of Alzheimer’s, but Richardson feels his team’s findings add an important piece to the puzzle. “I think these results demonstrate that more attention should be focused on potential environmental contributors and their interaction with genetic susceptibility,” he says in a press release.
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By Anne-Marie Botek, AgingCare.com Editor