The effects of mercury on the brain have been understood for a long time. Overt mercury exposure (such as industrial exposure) has been known to affect motor function, causing shakes, slurring of speech and physical impairment. Other effects – often known as "Mad as a Hatter Syndrome" – refer to dementia, depression and loss of memory.

In fact, the Mad Hatter was quite a stereotype. At one time, milliners used heated mercury to size felt when making hats, often touching their brushes to their tongues after dipping it into the mercury solution. It was not uncommon for such people to be considered eccentric after such exposure.

Nowadays, such a large exposure to mercury is rare. The Occupational Safety and Health Administration (OSHA), World Health Organization and others have raised public consciousness about the dangers of many toxic substances. With this information came guidelines for the safe handling and disposal of such chemicals. These guidelines are used every day, especially in the offices that use the largest non-industrial quantity of mercury in the world – your local dentist office.

"Silver" dental fillings are comprised of roughly 50% mercury. Many studies have shown that mercury – unique among metals for its physical properties, such as being liquid at room temperature, evaporating easily, and so on – is easily dissociated from its parent filling, thus entering the bloodstream.

It has long been known that mercury is not contained when it enters the human body. It has the ability to cross several barriers, particularly the placenta and the blood-brain barrier. The latter is a vastly important protective mechanism, an impediment that selectively opposes the passage of ions (electrically charged particles) and large molecular compounds from entering the brain.

Once mercury passes the blood-brain barrier, it can accumulate in the brain tissue due to its affinity with lipoproteins (fat-protein combinations). Here it may bring about a myriad of possible health defects. Mercury is more toxic than lead, cadmium and even arsenic. J. Curt Pendergrass, Ph.D., a toxicologist from the University of Kentucky is the author of numerous scientific papers and very familiar with metallic toxins such as mercury. One of the findings Dr. Pendergrass has presented is the effect of mercury on brain tubulin.* Tubulin is the most abundant protein found in brain matter, and is frequently used to determine neurological impact of differing toxins. By studying the pattern of inhibition, it is possible to determine the specific impact of a toxin and whether or not it is a contributor to particular diseases.

Dr. Pendergrass’ findings indicate that not only does mercury from silver fillings affect the brain tubulin, but does so in a pattern identical to Alzheimer’s disease. The links between mercury and Alzheimer’s have been suggested for years. This is the first study, however, showing a direct effect of mercury on the brain.

In contrast, two well-publicized studies directly refute these findings. The first, referred to as the Nun Study, showed no reduction in the performance of eight standardized tests of cognitive function relative to the number of chewing surface amalgam fillings in the month. This test focused on a population of 129 Roman Catholic nuns between the ages of 75 and 102. Due to their cloistered lives, the environmental conditions were deemed similar for all.

The second study, which received press in the Journal of the American Dental Association (ADA), involved 68 patients with Alzheimer’s disease (AD) and 33 without, following their deaths. The researchers assayed multiple regions of the brain for the presence of mercury. According to their findings, there was no significant correlation between the number, surface area or ages of the dental fillings and the appearance of AD, and no significant difference between mercury levels of AD and non-AD subjects.

These studies would certainly seem to refute Dr. Pendergrass’ findings of the suppression of brain tubulin but for three factors. First, the two studies cited above were submitted to legitimate scientific journals that peer-review all applications. These studies were rejected. Secondly, they were published in the Journal of the ADA, which is not peer-reviewed, not scientific in focus, and accepts advertising monies from the makers of dental amalgams. Thirdly, Dr. Pendergrass’ study, along with seven other studies that link mercury levels with increased incidence of Alzheimer’s disease, were all published in peer-reviewed scientific journals. (Interestingly, dentists authored the two well-publicized studies. The other, peer-reviewed articles were published by toxicologists and neurologists.)

Obviously, the debate over mercury and its effect on the brain continues. What we are left with are not answers, but more questions. Is mercury a causative factor in neurological impairment? Yes. Does it affect everyone? We don’t know. Does it have the same effect on everyone? We don’t know. Is the toxin cumulative or dose-dependent? Again, we don’t know.

What we do know is that there are alternatives. Whether it is prudent to accept a toxin into the body or not is an independent choice. If you have questions regarding the alternatives, there are two excellent resources in your community. One is an informed, biological dental office (that is, one that does not use dental amalgam). The other is your alternative health care provider. There are numerous means to determine what sort of dental restoration is right for you.

Dr. Burton Miller welcomes your questions on this and other dental matters. Dr. Miller has been practicing dentistry for over 30 years. He and his health-centered dental team are committed to whole body wellness. Call 277-2600.

For more information on Dr. Pendergrass’ work, see www.atlcorp.com