True Alzheimer's-in contrast to various forms of senility -is diagnosed through evidence of actual physical damage to the brain. Alzheimer's patients suffer from impaired tubulin, the protein needed for healthy neurofibrils, or connective nerve tissue; this leads to a 'neurofibrillary tangle', where messages in the brain don't connect properly.
But this is just the end result. Medicine has difficulty treating Alzheimer's because it may not be a specific illness with particular symptoms. What people may be suffering from is brain poisoning-from many sources.
A number of environmental onslaughts can cause damage to the brain but, mostly, they're heavy metals, including aluminium and mercury-usually from amalgam fillings.
Indeed, a recent review of all the evidence for mercury toxicity concluded that the concentration of mercury in the brain correlates with the number of amalgam fillings in the mouth. The higher the number of fillings, the greater the amount of mercury stored in the brain. Ex-smokers trying to quit fare even more badly; those with silver fillings who chew nicotine gum may, in the long term, increase their mercury levels by a factor of 10 (N Engl J Med, 2003; 349: 1731-7).
Other evidence shows that mercury vapour released by chewing is inhaled into the lungs, where it rapidly enters the bloodstream and swiftly makes its way into the brain (J Orthomol Med, 1997; 13: 31-40). At least seven major amalgam manufacturers have issued warnings that amalgam fillings can cause mental deterioration.
Although new evidence strengthens the connection between aluminium poisoning and Alzheimer's disease (see Special Report), in one animal study from the University of Kentucky, rats fed aluminium had no change in tubulin levels, whereas those given mercury displayed diminished tubulin levels similar to those typically seen in Alzheimer's patients. Although animal studies may not apply to humans, studies at the University of Calgary Medical School have shown that mercury markedly inhibits tubulin levels, both in rats and in monkeys (J Neurochem, 1994; 62: 2049-52).
Certainly, it is difficult to dismiss the mounting evidence of some role for aluminium in the development of the disease. It may be, as some suggest, that the brain depleted of protective minerals like zinc and selenium, and overwhelmed by mercury, is susceptible to aluminium deposition. Or it could simply be that both aluminium and mercury contribute.
Aluminium is pervasive-in our water, commercially prepared orange juice, food, cosmetics, drugs, deodorants, cooking utensils and flip-top cans. Nevertheless, the amounts that the brain is exposed to do not compare with the dose of mercury it receives when it is inhaled with every chew.
Another interesting causal factor is excess glutamate, a common amino acid and one of the main excitatory neuro-transmitters used in the central nervous system. When the receptors involved become overstimulated, this is thought to cause tubulin damage.
One of the chief sources is monosodium glutamate, a sodium salt of glutamic acid that is converted to glutamate. This excitotoxin is routinely added to most processed foods.
Modern medicine is built upon tidy classifications. Rather than seeing a disorder as unique to the individual, illness tends to be given a label with an organic or infective cause.
The reason we don't have a cure for Alzheimer's is that medicine persists in attempting to fix a 'faulty' brain chemical. The cause of Alzheimer's appears to be, purely and simply, environmental insults. Prevention and possibly even a cure for Alzheimer's is simple: stop poisoning your brain with toxic metals and junk food.