The causes of Alzheimer’s Disease have long eluded scientists, who suspect the disease is caused by some combination of genes, the environment, and lifestyle. A combination of those factors cause pretty much every disease known to man, so without specifics, it’s pretty tough to figure out how to avoid the disease or how to treat it (though medical advances are being made). Now, scientists from Rutger’s University may have shed some light on a possible environmental factor responsible for the disease: DDT.
The study, published yesterday in the JAMA Neurology journal, focused on a chemical called DDE, which is produced during the synthesis of the famously banned pesticide DDT. They measured the amount of DDE in the blood of healthy patients and compared it to the amount of DDE in the blood of patients with late-onset Alzheimer’s.
The researchers found that, on average, the group of subjects that had Alzheimer’s had almost four times as much DDE in their blood as the healthy patients. But not every subject with Alzheimer’s had levels that high, and even the study authors suggest that the correlation is far from simple and doesn’t reveal the whole story about the causes of Alzheimer’s. The scientists also confirmed that DDE levels in the blood correlate with DDE levels in the brain, meaning that the compound doesn’t just stay in the bloodstream.
According to the CDC, although DDT has been banned for over 40 years, 75-80% of blood samples it reviews contain DDT. Wow — that’s staying power. Can you imagine if it hadn’t been banned? One of the study authors puts it this way: “Genetics loads the gun. Environment pulls the trigger.” Still, the study doesn’t prove a causal link between the two — at least, not yet.
Testing for DDE may one day become a routine part of Alzheimer’s screening, and it’s possible that addressing those levels may lead to early treatment options for those who have a particularly high amount of the chemical in their blood. Still, even if detected, it might not be possible to reverse or ameliorate the effects of DDT exposure.
DDT was first used as an insecticide by Swiss chemist Paul Muller in 1939, and then was later used in WWII to help treat typhus and malaria, earning Muller a Nobel Prize in Chemistry. Rachel Carson’s Silent Spring first raised awareness about the dangers of the pesticide, which was banned 10 years later in the US. Some countries still use DDT, especially to protect against malaria, so imported foods can still contain the chemical. I guess that’s one benefit of lab-grown meat?