Lead exposure and Alzheimer’s disease: The epigenetic link
Lead poisoning has been recognized as a significant health problem worldwide. New research in the field of epigenetics now points to yet another hazard. Animal models have shown that exposure to the heavy metal in the early stages of development can modify the genome and increase the risk for Alzheimer’s disease later in life.
By Syed Waseem Bihaqi
The emerging field of epigenetics studies modifications to the DNA that can switch a gene’s expression on or off. These changes do not modify the genetic code, but instead affect how cells “read” genes.
One of the most extensively studied types of epigenetic modification is DNA methylation – the addition of a methyl group to part of the DNA molecule, which restricts certain genes from being expressed. This “chemical cap” regulates a large number of cellular processes and is essential for the normal development of mammals. Any defect in epigenetic gene regulation can have deleterious consequences, which may last an entire lifetime.
According to a recent paper, published in Reviews on Environmental Health, accumulating evidence suggests that environmental factors can affect the developing brain by modifying DNA methylation. An important and concerning example is exposure to the most widespread metal on earth – lead.
Childhood lead exposure and Alzheimer’s
Lead is known to be hazardous to every organ in the human body, with the brain being particularly sensitive, especially in the early developmental years. Past epidemiological studies have shown that young children exposed to lead tend to have lower IQs.
Furthermore, researchers from the University of Rhode Island have now been able to provide convincing evidence that early-life lead exposure, in both primates and rodents, results in an increased expression of Alzheimer’s disease-associated genes and cognitive deficits later in life. In concert with these findings, primates exposed to lead showed reduced levels of enzymes that control the DNA methylation.
According to Dr. Syed Waseem Bihaqi from the George and Anne Ryan Institute for Neuroscience, further research on the link between heavy metals and epigenetic changes is now urgently needed: “The knowledge gained will have immense implications for the prevention and treatment of metal exposure.”
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