Although the neurotoxicity of aluminum is well established, the association between the metal and dementia or associated disorders remains a subject of debate. In this article, we present a review of articles published on epidemiologic studies of this subject. Different sources of exposure are considered (occupational exposure, aluminum-containing products), with emphasis on drinking water. We separate the various health effects of aluminum into three categories: neurological disorders (other than cognitive decline or AD); cognitive decline; and dementia or Alzheimer's disease. Furthermore, we present the results obtained on silicon in drinking water, a chemical constituent that interacts with aluminum. We conclude that not enough epidemiological evidence supports a link between aluminum in drinking water and AD. The role of silica in drinking water has been less studied, and clear results have not yet emerged.