Although amalgam dental fillings have been in widespread use for around 150 years, this started to change in the mid-1980s, when evidence began to emerge that mercury vapour was being released from these fillings. However, there was not much supporting evidence at that time. Indeed, as recently as 1997, the World Dental Federation (FDI) and the World Health Organization joint consensus statement on dental amalgam stated: "No controlled studies have been published demonstrating systemic adverse effects from amalgam restorations."
However, recent advances in technology have allowed the mercury-Alzheimer's theory to be tested directly on brain tissue samples from known sufferers of the disease. Two independent university laboratories have now shown that minute amounts of mercury can damage the membranes of growing brain cells.
A team of Swiss and Belgian scientists exposed brain cells to minute amounts of mercury and observed changes that mimicked "all the biochemical lesions of AD" (J Neurochem, 2000; 74: 231-6).
A year later, University of Calgary researchers found that mercury caused the "neurofibrillary aggregates" characteristically found in the brains of AD sufferers (NeuroReport, 2001; 12: 733-7).
In response to the concerns these findings raise, Sweden has banned mercury fillings, and Austria and Germany have restricted their use. The latest legislature to consider a ban is California's, where there's a bill in place to outlaw the use of mercury-containing dental fillings starting in 2007