Exposure to DDT may be associated with development of Alzheimer's disease
A new research published in the journal JAMA Neurology has found that people who are exposed to pesticides like dichlorodiphenyltrichloroethane (DDT) are at an increased risk of developing Alzheimer’s disease compared to people who have no trace of the chemical in their blood. The research was carried out by Jason Richardson from the Rutgers Robert Wood Johnson Medical School in Piscataway, New Jersey, along with his colleagues.
DDT has been banned in the US since 1970s, but is still used rampantly as a pesticide in many developing countries. Even the WHO has approved its use in certain places for combating malaria. However, it directly affects the central nervous system and may play a role in neuro-degenerative disorders. The long term side-effects of DDT are still not known.
For their study, the researchers conducted a case control study involving 86 patients suffering from Alzheimer’s disease and 79 control participants from the Emory University Alzheimer’s Disease Research Center and the University of Texas Southwestern Medical School’s Alzheimer’s Disease Center. The blood levels of all the participants were analyzed. It was observed that the levels of dichlorodiphenyldichloroethylene (DDE), the metabolite of the pesticide DDT were almost four times higher in patients suffering from Alzheimer’s disease compared to control participants. DDE was found in the blood samples of 80% patients of Alzheimer’s disease and 70% control participants.
The researchers also found that both DDT and DDE increase the levels of amyloid precursor protein, which plays an important role in the plaque formation in brain, characteristic of Alzheimer’s disease. It was also observed that carriers of an APOE4 ε4 allele are more susceptible to the effects of DDE.
Based on the results of the study, the researchers have opined that identifying people who have elevated levels of DDE in their blood and who are a carrier of APOE4 ε4 allele may lead to early identification of people more likely to develop Alzheimer’s disease. However, they have stressed the fact that it is important to replicate the results in a larger study population before any inference can be drawn about the causal relationship between DDE and Alzheimer’s disease. Critics of the study have pointed out that there is no data which shows that Alzheimer’s disease is more common in places where DDT use is rampant.
Editor: Dr. Bimal Rajalingam MBBS DNB