A study led by Jinfang Wu and other scientists suggests that early exposure to environmental toxins may lead to Alzheimer's disease much later in life.
The study showed that primates exposed to lead as infants showed Alzheimer's disease (AD)-like pathology years later.
The researchers exposed monkeys to lead levels that produced no obvious sign of toxicity from their birth until the age of 400 days.
The blood lead levels of monkeys in the experimental group remained indistinguishable from that of controls by young adulthood.
Upon examination at approximately 23 years of age, it was found that the brains of lead-exposed monkeys exhibited many hallmarks of Alzheimer's disease.
The researchers noted that DNA methyl transferase activity was reduced in lead-exposed monkeys, while oxidative damage to DNA was increased.
The findings show that lead exposure early in life may predispose animals to later neurodegenerative disease, possibly through alterations in DNA methylation and oxidation.