Credit: FIU
Key Points:
- The insecticide DDT was found to elevate amyloid-beta levels in the brain, which increases firing between neurons and eventually culminates in Alzheimer’s.
- Specifically, researchers learned that DDT kept sodium channels open, which resulted in the increased firing of neurons and the development of plaque found in the brains of Alzheimer’s patients.
- Researchers are now testing drugs that act on sodium channels in order to halt the chain reaction initiated by DDT.
Popularized by Rachel Carson’s “Silent Springm” dichlorodiphenyltrichloroethane (DDT) is an insecticide toxic to humans at certain levels. Researchers have known of a link between DDT and Alzheimer’s disease for some time, but a new study conducted by scientists at Florida International University (FIU) illustrates how the toxin promotes the development of Alzheimer’s.
Some scientists believe that Alzheimer’s is caused by the Amyloid Hypothesis, which suggests that an increase in amyloid-beta triggers a chain-reaction that results in the presence of plaques that result in the disease. Now, the FIU researchers, who published their study in Environmental Health Perspectives, found that continuous exposure to DDT causes an increase in levels of amyloid-beta.
"The vast majority of research on the disease has been on genetics—and genetics are very important—but the genes that actually cause the disease are very rare," says Jason Richardson, a professor at the university. “Environmental risk factors like exposure to DDT are modifiable. So, if we understand how DDT affects the brain, then perhaps we could target those mechanisms and help the people who have been highly exposed.”
Even though DDT as an insecticide is no longer used in the United States, it was used extensively during the middle part of the last century. The population exposed to it back then is now aging into a category that puts them at risk of Alzheimer’s disease.
In the study, DDT was found to cause an increase in amyloid-beta levels by promoting an increase in activity between neurons. The researchers discovered that tetrodoxin, a sodium channel blocker that inhibits the firing of neurons, prevented an elevation in amyloid-beta levels.
The researchers believe their study could act as a blueprint to develop ways of treating people who have been exposed to high levels of DDT. The researchers’ goal is to utilize their understanding of the link between DDT and Alzheimer’s to test the efficacy of existing drugs that act on sodium channels.