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Scientific VIEW

Alzheimer's Link to Aluminum Explored

August 27, 1986|BETTYANN KEVLES

In some parts of the world it may be safer to drink the water than the tea. It's not the caffeine or the tannic acid that's troubling professors A.-M. Coriat and R. D. Gillard at University College, in Cardiff, Wales; it's aluminum! In a letter to Nature they warn that tea grown where potassium alum is used as fertilizer tolerates vast quantities of aluminum in its leaves. Anyone drinking more than a liter of such tea a day (not uncommon in Britain) is endangered.

But endangered by what? Closer to home health food stores are hawking aluminum-free deodorants, antacids and baking powders, suggesting that aluminum is somehow responsible for the degenerative, and thus far uncurable dementia of mostly older people known as Alzheimer's disease. There is some indication that the brain tissue of Alzheimer's victims contains excessive aluminum deposits.

An unscientific survey of my friends and neighbors revealed that many of them had already emptied their kitchens of aluminum cookware, their cupboards of aluminum-enriched products. But they have only scratched the surface if they are going to achieve an aluminum-free environment, because aluminum comprises 8% of the earth's crust in the form of aluminum silicate. Moreover, as alum, it purifies most urban water supplies and, as an ingredient in asphalt, fills the air with dust.

The case against aluminum is largely circumstantial, beginning with the identification of the condition in 1906 by Alois Alzheimer, just as aluminum had come into industrial use. This does not mean that the disease did not exist until it was named. We have no way of knowing the incidence of Alzheimer's in earlier populations. We can surmise, however, that it must have been less frequent than it is today because, until recently, few people lived to be 70, the average age of onset. Nor can we know if there has been any increase in the amount of aluminum in the human body in the past century because we do not have access to preserved brain tissue from earlier generations.

We do not really know if an aluminum-free environment would be healthier. Aluminum is present in the brain tissue of most Americans today. In small amounts it seems harmless. Aluminum may substitute for other trace metals as part of the structure of certain enzymes but it is not required for good health like zinc or iron.

If not necessary, the question remains: is too much toxic? The answer appears to be yes. But how much, and toxic to whom and in what form is unknown. The scientific evidence is episodic and sometimes contradictory. About 80% of individuals who have been diagnosed as having Alzheimer's disease are found, on autopsy, to actually have had the disease. Microscopic examination of their brain tissue reveals deteriorated cells with deposits of plaque and tangled neurons, often containing deposits of aluminum.

But not always. A study of the tissue of Alzheimer's victims in Kentucky, where until recently alum was not used to purify the water supply, found no aluminum buildup. Yet there are as many victims of Alzheimer's in Kentucky as elsewhere, an absence of aluminum notwithstanding. Likewise, aluminum has been found in the brain tissue of non-Kentuckians who died with their faculties intact.

There is, however, a direct connection between aluminum and another kind of dementia, dialysis encephalopathy. In a single episode in Florida a group of patients on kidney dialysis began showing signs of dementia. Investigators discovered that the water used in the procedure was excessively high in aluminum. Heavy concentrates of the metal were going directly to a vital organ, the kidneys, and then right to the brain. Unlike experience with Alzheimer's patients, however, when the dialysis was stopped, the dementia was reversed and the patients returned to normal. There have been occasional instances of halting the progress of Alzheimer's disease, but there is no record of improvement.

What does this all prove? Some dementia is coincidental with the presence of aluminum in the brain. But there is no causal connection. Biochemists working in the Southern California Alzheimer's Consortium agree that the aluminum deposits may be a secondary effect, may reflect a genetic inability to metabolize aluminum which, together with other genetic factors, facilitates the onset of Alzheimer's (there is a hereditary pattern to the illness). At the same time they say that the aluminum deposits may antedate the condition and be totally unrelated to it, or may in some as yet undetermined way signal the onset of the disease.

Alzheimer researchers Carl Cotman at UC Irvine and Caleb Finch at USC have not changed their buying habits and suggest that it is premature and even idiosyncratic to give in to hysteria by avoiding ingesting aluminum. But Eugene Roberts at the City of Hope disagrees. He has changed his deodorant and antacid to aluminum-free products.

Roberts argues that this is easy enough to do. While his colleagues say avoidance of such products can't do much good, he responds it can't do any harm. Meanwhile, research in laboratories such as the City of Hope is closing in on the connection between the metal and the disease. Within the next decade we should know if aluminum triggers dementia, or if it is simply a red herring in the mystery of Alzheimer's and other diseases of the brain.

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