Controversial study suggests link with Alzheimer's disease
can aluminium, commonly used to make utensils, be a health hazard? The long-standing question was revived recently with researchers suggesting a possible role of the versatile metal in the death of a British woman. Carole Cross of Camelford village in Cornwall died of Alzheimer's disease 16 years after an industrial accident caused aluminium contamination of drinking water.
A chemical analysis showed that Cross had high levels of aluminium in her brain tissues, say Christopher Exley, a chemist at the Keele University (uk) and Margaret Esiri, a University of Oxford neurologist. Cross did not have a family history of the disease but was predisposed, through a gene called apoe, to a common form of Alzheimer's, says Esiri.
Cross, however, had succumbed to a rare form of Alzheimer's, not to the form she was predisposed to. Whereas the disease usually affects people in their 70s or 80s, Cross was just 58 when she died in 2004. Previous studies of transgenic mice expressing a similar gene have shown that feeding them aluminium in drinking water can cause similar symptoms at a young age.
Cross and 20,000 other people in her village were exposed to aluminium sulphate -- used in wastewater treatment -- when a truck driver mistakenly emptied 20 tonnes of the chemical into a drinking water tank in 1988. The villagers drank the polluted water for several weeks before the contamination was found out.
Cross's case has reopened the possibility that aluminium could be linked to Alzheimer's disease, say the two researchers in their study, which was published online on April 20, 2006, in the Journal of Neurology, Neurosurgery and Psychiatry. According to a news report on nature.com, several villagers are suffering from dementia, a symptom of Alzheimer's disease. Nature quoted Esiri as saying aluminium is firmly linked to some temporary forms of dementia. For instance, dialysis patients living in areas where the aluminium content in water is high, sometimes experience 'dialysis dementia'.
But a neuropathologist who has written a commentary in the same journal on the Camelford case says the supposed link between aluminium and Alzheimer's disease is controversial. Aluminium is often found in the twists of deformed protein, called 'neurofibrillary tangles', that characterise the disease. But there is no strong evidence of its involvement in the disease, cautions Daniel Perl, who works at the Mount Sinai School of Medicine in New York. Of the 20 most common elements on earth, aluminium is the only one not involved in any essential biological process, he says. Esiri counters by saying that Cross's protein tangles were found in the blood vessels, not in the brain tissue. She suggests the disease could have originated in the gut, reaching the brain through the bloodstream.
The controversial study may rekindle fears over using aluminium pots and pans, although experts say aluminium present in utensils is insoluble and, therefore, not dangerous. The only way to ingest aluminium would be by cooking acidic foods such as tomato, which react with the metal.
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