The case for aluminum as a risk factor for Alzheimer's
Aluminum is the most common metal in the earth's crust and the third most common element after oxygen and silicon. It is also commonly found in the brains of people who have died of Alzheimer's disease. It was this discovery, first made in the early 1970s, that implicated aluminum as a possible risk factor in the development of Alzheimer's disease. This was the first evidence in the case for aluminum as a risk factor, but not the last.
It was discovered that the presence of aluminum in dialysis fluid was the major reason for the development of dialysis encephalopathy in patients with kidney failure. Dialysis encephalopathy is a form of dementia with some clinical symptoms similar to Alzheimer's disease. The dementia was eliminated by reducing the aluminum concentration in the dialysis fluids.
On the island of Guam, a region which has a high content of aluminum in the water, 10 percent of the inhabitants suffer from a disease called amyotrophic lateral sclerosis with Parkinson's dementia. Their brains have aluminum-containing neurofibrillary tangles similar to those in Alzheimer's disease.
A study done in 1990 explored the association between Alzheimer's disease and exposure to aluminum through the lifetime use of antiperspirants and antacids. The overall risk for Alzheimer's was 60 percent greater than normal among persons using aluminum-containing antiperspirants with a trend toward a higher risk with increasing frequency of use. The risk was as high as 320 percent among those who reported the greatest use of aluminum-containing antiperspirants.
Another study published in the Lancet showed that the progression of dementia associated with Alzheimer's disease was significantly slowed by administering desferrioxamine, a chemical known to remove aluminum and other metals from the body.
In a study reviewing the epidemiological evidence linking aluminum and Alzheimer's disease, the author, T. P. Flaten, found that nine out of 13 published studies showed a direct correlation between the prevalence of Alzheimer's disease and aluminum concentrations in the drinking water. One study showed the risk of developing Alzheimer's disease to be 50 percent greater where drinking water contained higher levels of aluminum.
The evidence implicating aluminum in the causation of Alzheimer's disease seems quite strong. Why then is there a controversy? Well, when you look below the surface of the evidence presented in these studies, there are some serious flaws that raise questions about their validity.
The case against aluminum as a risk factor for Alzheimer's
Aluminum in the brains of Alzheimer's patients - Although many studies have been done showing aluminum concentrations in the neurofibrillary tangles and the amyloid plaques of Alzheimer's disease patients, other studies have found no aluminum in Alzheimer's brains. The critics of the studies showing aluminum in the brains of Alzheimer's disease patients contend that such findings were caused by contamination of tissue prepared using conventional chemical techniques. In these techniques, aluminum silicate is used in tissue-staining. In two studies done using nuclear microscopy, a new technique that does not require chemical tissue-staining, one of the studies found no aluminum in amyloid plaques, and the other found no aluminum in neurofibrillary tangles.
Next week's article will continue the case against aluminum as a risk factor for Alzheimer's and list the sources of aluminum in the environment.
Mary Lou Williams, M. Ed., is a writer and lecturer in the field of nutrition. She welcomes inquiries. She can be reached at 267-6480.