Role of developmental exposure to environmental agents in altering the disease process is well known. Exposure to chemical agents at critical periods of development may cause some permanent changes in the functioning of various vital systems including the nervous system in the organisms. It is not surprising to see an extensive response due to exposure to chemical agents early in life as the organ systems are more vulnerable to chemical insults during developmental stages. In some cases the response to low level environmental insults may not be obvious until adult or old age. Results from several studies have shown such latency in response to the nervous system leading to neurodegeneration in old age. Studies conducted in murine and primate models provided ample evidence for the association of developmental exposure to low levels of heavy metal lead (Pb) and Alzheimer's disease-like pathology during senescence. It is not clear about the reasons behind such response; however, the contribution of epigenetic mechanisms could explain the role of early events in life in inducing the late life abnormalities of nervous system. It is possible that environmental agents epigenetically modulate the gene regulation to persist the response silent for a long period of time and to result pathological outcomes significantly later in life. This article will summarize the association of early life exposure to environmental agents and late-life abnormalities with an emphasis on developmental exposure to Pb and neurodegeneration in old age.