Lead has been increasingly associated with cognitive decline and Alzheimer's disease. Studies in humans are scarce. While observational studies suggest an association between long-term exposure to lead and cognitive performance in elderly subjects, studies in patients with a confirmed diagnosis of Alzheimer's disease are scarce and fail to reach agreement. Laboratory experiments, however, show that lead aggravates the pathologic cascades of Alzheimer's disease in various ways and suggest a role for lead as a risk factor for Alzheimer's disease. Conclusively, it seems prudent to recommend the avoidance of lead as an integral part of a preventive strategy for Alzheimer's disease.