DDT exposure linked to Alzheimer's
19 February 2014
A study by UT Southwestern Medical Center has found that exposure
to DDT may lead to Alzheimer’s disease later in life.
The study, published in the journal JAMA Neurology,
found elevated levels of the DDT metabolite, DDE, that were 3.8
times higher in patients diagnosed with Alzheimer’s disease in
comparison to control subjects.
Previous studies have linked chronic diseases such as cancer and
diabetes to DDT, but this is the first clinical study to link the
pesticide to Alzheimer’s disease. Alzheimer’s disease is the most
common neurodegenerative disease worldwide and is expected to
increase three-fold over the next 40 years, according to the
These findings may help lead to the development of early
biomarkers that can determine whether a person will develop
Alzheimer’s disease later in life due to DDT exposure.
Researchers made the link between DDE and Alzheimer’s by
measuring three components – blood serum levels, severity of the
patient’s Alzheimer’s disease as measured by the Mini-Mental State
Examination (MMSE) and its relation to serum DDE levels, and the
reaction of isolated nerve cells to DDE. Treatment of human nerve
cells with DDE caused them to increase the production of the amyloid
precursor protein that is directly linked to Alzheimer’s disease.
DDT (dichloro-diphenyl-trichloroethane) was used extensively as
an insecticide in the 1940s, but has been banned in the United
States since 1972 after scientists linked the compound to wildlife
health and environmental concerns. DDT is still used in other
countries to combat the spread of malaria.
“We have additional studies underway that will seek to directly
link DDT exposure to Alzheimer’s disease,” said co-author Dr. Dwight
German, Professor of Psychiatry at UT Southwestern. “If a direct
link is made, our hope is to then identify the presence of DDE in
blood samples from people at an early age and administer treatments
to remove it.”
The studies were conducted in partnership with researchers at
Emory University School of Medicine and Rutgers Robert Wood Johnson
Medical School. Participants in the study underwent preliminary
testing to ensure that they didn’t have symptoms of other
dementia-related diseases, and were an average age of 74, while the
control subjects were on average 70 years old. The study found
elevated levels of DDE in blood samples of 86 patients with
Alzheimer’s disease as compared to 79 control patients from the UT
Southwestern Alzheimer’s Disease Center and the Emory University
Alzheimer’s Disease Center.