Although no epidemiological study reports the effects of long-term Pb exposure, experimental studies in rodents (Bihaqi et al., 2014; Gąssowska et al., 2016) and monkeys (Bihaqi and Zawia, 2013) indicate that early exposure to Pb augments the phosphorylation of Tau, and is associated with an increase in the level of the cyclin-dependant kinase 5 (Cdk5), a major Tau kinase that is involved in abnormal phosphorylation of Tau in AD brain (Cruz and Tsai, 2004). The gene discussed is CDK5; the disease is Alzheimer disease.