Aluminum concentrations in drinking water and risk of Alzheimer's disease.

To investigate the relation of aluminum and silicon in drinking water to risk of Alzheimer's disease, we carried out a case-control study in eight regions of England and Wales. Subjects were identified from the records of neuroradiology centers, and diagnoses were confirmed by a review of hospital case-notes. Exposure to aluminum and silicon in drinking water was estimated from residential histories of 106 men with Alzheimer's disease, 99 men with other dementing illnesses, 226 men with brain cancer, and 441 men with other diseases of the nervous system. All subjects in the study were between 42 and 75 years of age. There was little association between Alzheimer's disease and higher aluminum or lower silicon concentrations in drinking water when cases were compared with any of the control groups. The results indicate that any risk of Alzheimer's disease from aluminum in drinking water at concentrations below 0.2 mg per liter is small, and they give no support for a protective role of silicon.