Exposure to the banned pesticide DDT may contribute to the onset of Alzheimer’s disease in adults, according to a new study.
Researchers found that people with Alzheimer’s disease had blood levels of DDE, a prominent component of DDT, that were four times higher than control patients. The researchers discovered the high levels after comparing blood samples from 86 older adults diagnosed with Alzheimer’s to 79 healthy control participants, according to the study published in the medical journal JAMA Neurology.
“This is one of the first studies identifying a strong environmental risk factor for Alzheimer’s disease,” said study co-author Dr. Allan Levey, the director of Emory’s Alzheimer’s Disease Research Center and chair of neurology at Emory University School of Medicine in a statement. “The magnitude of the effect is strikingly large — it is comparable in size to the most common genetic risk factor for late-onset Alzheimer’s.”
Although the researchers could not be certain of how exactly DDT exposure is contributing to Alzheimer’s, they found promising leads. When they exposed brain cells in a dish to high levels of DDT or DDE, they found higher levels of a protein that leads to beta-amyloid–a protein fragment that causes plaque to build up in the brain and leads to Alzheimer’s disease.
DDT was formally used in U.S. agriculture to control mosquito populations, until its toxicity levels led it to be banned here in 1972. However, the toxins can remain in the human bloodstream for years. The reason researchers think that the chemical has its greatest influence on older adults is because DDE may be gathering in the tissues of the elderly people, and affecting them as they age.
It’s too soon to say whether DDT is a primary contributor to Alzheimer’s. The study was small, and some of the people with the disease did not have detectable levels of DDE, while some of the healthy participants did have high levels, but no disease. Genetics continue to be a primary driver for Alzheimer’s, but other risk factors help the medical community paint a greater picture of the disease which could lead to better understand and treatment development.