The results showed that DDE serum levels were nearly four times higher in individuals with AD than in controls. The highest blood levels of DDE was associated with low scores on cognitive function tests, as well as the presence of the APOE4 genotype. In addition, the researchers found that DDE increased levels of amyloid precursor protein, after exposing human neuronal cells to DDE in vitro.
“This is one of the first studies identifying a strong environmental risk factor for Alzheimer's disease," commented coauthor Allan Levey, M.D., Ph.D., director of Emory's Alzheimer's Disease Research Center and chair of neurology at Emory University School of Medicine. "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." The study’s authors noted that identifying people who have elevated levels of the long lasting toxin and carry an APOE4 allele may lead to early identification of some cases of AD.
To read more about how environmental factors can contribute to psychiatric disorders see the Psychiatric News articles, “Autism Linked to Air Pollution In Preschool Children” and “Destructive Mining Practice Worsens Depression in Appalachia.”