Pesticide Banned In The USA Linked To Alzheimer's Disease
January 29, 2014

Pesticide Banned In The USA Linked To Alzheimer’s Disease

Rebekah Eliason for – Your Universe Online

For over 40 years scientists have recognized that DDT, a synthetic pesticide, harms bird habitats and is a threat to the environment. Although DDT was banned in the United States in 1972, other countries continue to use it as a pesticide.

According to a new study from Rutgers University, exposure to DDT may cause increased risk and severity of Alzheimer’s disease. This is particularly true for people over 60 years of age.

As DDT breaks down, it leaves the chemical compound DDE. In patients with late-onset Alzheimer’s disease, DDE levels in the blood were higher than in people who do not have the disease.

During WWII, DDT was introduced for insect control in livestock as well as to fight insect-borne diseases such as malaria. The researchers from Rutgers are the first to connect Alzheimer’s disease with a specific chemical compound. They believe it is crucial to study how DDT and DDE trigger neurodegenerative diseases such as Alzheimer’s.

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), said, "I think these results demonstrate that more attention should be focused on potential environmental contributors and their interaction with genetic susceptibility. 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.”

In the last 30 years, levels of DDT and DDE have significantly decreased in the United States, but the toxic pesticide is still present in 75 to 80 percent of blood samples collected for a national health survey conducted by the Centers for Disease Control and Prevention (CDC).

Scientists explain that the chemical can break down and be released into the environment over decades causing extended periods of exposure to the chemical. Also, DDT and DDE exposure occurs from imported fruits, vegetables and grains since DDT is still used in other countries. As well, Alzheimer's risk comes by way of eating fish from DDT-contaminated waterways.

In this study, 86 Alzheimer’s patients with an average age of 74 were compared to a control group of 79 people without the disease. Of the Alzheimer patients, 74 of them had DDE blood levels that were almost four times more than those in the control group.

Certain versions of the ApoE gene (ApoE 4) substantially increase the risk of developing Alzheimer’s disease. In patients with Alzheimer’s along with high blood levels of DDE, there was more severe cognitive impairment exhibited than in the patients without the gene. According to brain cell studies, DDT and DDE can increase the amount of a protein that is linked to plaques which are considered to be an important factor in Alzheimer’s disease.

The proteins are known as amyloid proteins and are very sticky and form in regions of the brain connected to memory, learning and thinking. As the disease progresses, these proteins break apart and clump together in the brain. Richardson says this new research is important because it suggests that DDT and DDE may directly contribute to the process of plaque development.

“We need to conduct further research to determine whether this occurs and how the chemical compound interacts with the ApoE4 gene,” Richardson says.

Currently, five million Americans suffer from Alzheimer’s and with the aging of the Baby Boomer Generation, millions more are projected to contract the disease. Scientists have not yet pinpointed the exact cause of Alzheimer’s disease, but they believe it is caused by a combination of genetic, environmental and lifestyle factors. Richardson explained that most research about neurodegenerative diseases such as Alzheimer’s is focused on finding genetic factors.

“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,” says Richardson. “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.”

Scientists Ananya Roy, Stuart Shalat and Brian Buckley at the Environmental and Occupational Health Sciences Institute at Rutgers, Allan Levey and Maria Gearing at Emory University School of Medicine, and Dwight German at the University of Texas Southwestern Medical Center contributed to the research.

This study from Rutgers was conducted in coordination with Emory University Alzheimer’s Disease Research Center and the University of Texas Southwestern Medical School’s Alzheimer’s Disease Center.

The research paper was published online in JAMA Neurology on Jan. 27, 2014.