A recent study published in JAMA Neurology has identified one of the first environmental risk factors for Alzheimer’s by establishing an association between exposure to the pesticide DDT (dichlorodiphenyltrichloroethane) and Alzheimer’s disease. DDT was widely used as an agricultural insecticide in the United States until it was banned in 1972, in large part precipitated by Rachel Carson’s seminal work, Silent Spring, in which she exposed the chemical’s hazardous effects on human health. The pesticide is still in use, in part because of the World Health Organization’s recommendation to use DDT to prevent malaria.
Despite the passage of more than forty-years since it was banned, DDT is still found in human tissue. The chemical’s lipophilic properties mean that it persists in the environment and fat tissue long after exposure: in 2005, more than thirty years after it was banned in the U.S., the Centers for Disease Control detected DDT in almost all of the human blood samples they tested. It is DDT’s tendency to bioaccumulate that was found to be significant in the JAMA study, which found that patients with Alzheimer’s had almost four times more DDT in their tissue than those without the disease.
The researchers hope that the correlation will allow for early detection and intervention, which will slow the progression of the disease. Next, the researchers behind the study will try to replicate their findings in a larger sample size and determine the reason behind the association between DDT and Alzheimer’s.