Pesticides Possibly Linked to Alzheimer’s Risk

Earlier this year we wrote about links between pesticides and Parkinson’s disease. Now, researchers are saying that <"">pesticide exposure might also be linked to an increase in Alzheimer’s disease risks, said WebMD Health News.

The researchers said such exposure could adversely affect the nervous system, and noted that the study sheds some light on why some with risk factors for Alzheimer’s develop the disease, while others do not, said WebMD. “While no cause for Alzheimer’s disease has been found, [non-inherited] cases are likely due to a combination of genetic and environmental factors,” said Kathleen M. Hayden, PhD, of Duke University Medical Center, quoted WebMD.

According to WebMD, the current research points to how pesticides may affect acetylcholine release. Acetycholine is a chemical critical to memory, said Hayden, reported WebMD, which noted that Alzheimer’s—which affect some 5.3 million Americans—“disrupts memory, learning, and other mental functions.” The Alzheimer’s Association reports, said WebMD, that by next year, we will see about 500,000 new cases annually, with that figure reaching one million by 2050.

While Alzheimer’s cases have increased, so has pesticide use. WebMD reported that over 18,000 pesticides are licensed in this country, with over two billion pounds “applied” annually, citing Hayden.

The study involved over 4,000 participants 65 years of age and older, who lived in an agricultural county in Utah, and who are participating in a larger Alzheimer’s risk factors study, said WebMD, which added that about 750 residents indicated they worked with pesticides. Standard cognition tests were routinely taken and, at the Alzheimer’s Association 2009 International Conference on Alzheimer’s Disease, the researchers indicated that those who worked with pesticides were 53 percent likelier to develop Alzheimer’s, reported WebMD.

Ralph Nixon, MD, PhD, an Alzheimer’s expert at New York University and vice chair of the Medical and Scientific Advisory Council at the Association told WebMD, “You can look at environmental toxins as being something that promotes the root cause of the disease, or as a second hit. If someone is already predisposed to Alzheimer’s due to genetics, cardiovascular disease, or some other risk factor, the environmental toxin may push their risk over the top.”

In April, we wrote that researchers found a link between pesticide exposure and some cases of Parkinson’s disease, a central nervous system disorder that affects motor skills and speech. According to the LA Times, researchers have long believed that pesticides may cause Parkinson’s; experiments found that chemicals—specifically maneb, a fungicide and paraquat, an herbicide—do, in fact, cause Parkinson’s-like symptoms in animals.

The LA Times previously reported that California researchers found that people residing near fields where maneb or paraquat had been sprayed were 75 percent likelier—on average—to develop Parkinson’s and patients who developed early-onset Parkinson’s (prior to age 60), experienced twice the risk for the disease if exposed to either chemical alone, and four times the risk if exposed to both. Generally, the disease followed exposure, said the LA Times.

Reuters also previously reported that the results of another study of 319 Parkinson’s patients and 200 nonParkinson’s-affected relatives found that people diagnosed with Parkinson’s are more than two times likelier to report pesticide exposure over people not diagnosed with the disease. Reuters reported that insecticides and herbicides—specifically citing organochlorines, organophosphorus compounds, chlorophenoxy acids/esters, and botanicals—were responsible for increased risk of developing Parkinson’s.

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