Serum Pesticide Levels Linked to Alzheimer’s

New research finds a connection between elevated serum pesticide levels and risk for Alzheimer’s disease. A team of researchers including investigators from Rutgers University’s Robert Wood Johnson Medical School evaluated the association between serum levels of dichlorodiphenyldichloroethylene (DDE) and Alzheimer’s disease and whether the apolipoprotein E (APOE) genotype modifies the association. In a case-control study consisting of existing samples from patients with Alzheimer’s and control participants from the Emory University Alzheimer’s Disease Research Center and the University of Texas Southwestern Medical School’s Alzheimer’s Disease Center, serum levels of DDE were measured in 79 control and 86 Alzheimer’s cases. Researchers found levels of DDE were 3.8-fold higher in the serum of those with Alzheimer’s disease when compared with control participants. The highest tertile of DDE levels was associated with an odds ratio of 4.18 for increased risk for Alzheimer’s and lower Mini-Mental State Examination scores. The Mini-Mental State Examination scores in the highest tertile of DDE were −1.753 points lower in the subpopulation carrying an APOE ε4 allele compared with those carrying an APOE ε3 allele. Serum levels of DDE were highly correlated with brain levels of DDE, and exposure of human neuroblastoma cells to DDT or DDE increased levels of amyloid precursor protein. Researchers concluded that elevated serum DDE levels are associated with an increased risk for AD and carriers of an APOE4 ε4 allele may be more susceptible to the effects of DDE, and that identifying people who have elevated levels of DDE and carry an APOE ε4 allele may lead to early identification of some cases of Alzheimer’s disease. “It is probably a bit early” to gauge the significance of these findings for primary care physicians, says Jason Richardson, MS, PhD, associate professor at Rutgers University’s Robert Wood Johnson Medical School and lead study author. “We need to replicate our findings in a much larger cohort in order to definitely identify DDT/DDE exposure as a contributory factor to risk of Alzheimer’s disease.” However, he adds, “if this were to occur in the future, it might provide a way to identify people that may be at higher risk. This would be similar to how people with a family history would be identified as having increased risk.” —Mark McGraw Reference Richardson J, Roy A, et al. Elevated Serum Pesticide Levels and Risk for Alzheimer Disease. JAMA Neurology. 2014.