(Beyond Pesticides, May 28, 2010)
The repeated exposure to organophosphate and organochlorine insecticides can increase the risk of developing Alzheimer’s Disease (AD) or dementia later in life according to a new study published in the May issue of Neurology. The observational study entitled “Occupational exposure to pesticides increases the risk of incident AD” is one of very few studies to examine a link between pesticides and AD.
Researchers lead by Kathleen M. Hayden, PhD of Duke University Medical Center examined residents 65 years and older from an agricultural community in Cache County Utah. Participants were assessed for cognitive ability at the inception of the study and again after 3, 7, and 10 years. Data showed that those repeatedly exposed to any pesticides were more likely to develop AD or dementia. Researchers found a higher incidence of AD among those exposed to organophosphates and organochlorines. The risk of AD associated with organophosphate exposure was slightly higher than the risk associated with organochlorines. Researchers also found an increase in dementia among those exposed to organophosphates or organochlorines; however this increase was not statistically significant. Dr. Hayden said that more research was necessary to determine a causal link.
Organophosphates are known to reduce acetylcholine, a neurotransmitter important for learning, memory, and concentration in the human brain. Acetylcholine is also reduced in AD patients. Most drugs on the market to treat AD work by increasing the amount of acetylcholine. Ronald Peterson, MD, PhD, chair of the Alzheimer’s Association Medical and Scientific Advisory Council and professor of neurology and Cora Kanow Professor of Alzheimer’s Disease Research at the Mayo Clinic in Rochester, Minnesota said this may be a clue as to why organophosphates are associated with an increased risk of the disease.
Since many organochlorine insecticides such as DDT, dieldrin, and heptachlor were banned in the US, organophosphates have become the most common type of insecticide. An estimated 20 to 24 million lbs of Chlorpyrifos, a type of organophosphate, is applied annually in the United States. Organophosphate exposure has been linked to a host of diseases in humans including birth defects, ADHD, and liver damage.
Pesticide Action Network North America (PANNA) has a petition to stop the use of chlorpyrifos, and phase out all organophosphates.
Source: Medscape Today