Dear Doctor:D My husband and I have been reading about a possible connection between aluminum and Alzheimer's disease. Some reports even discourage the use of aluminum foil for cooking. Is there a connection between aluminum and Alzheimer's?
Dear Reader: Your worries center around the most-abundant metal and the third-most abundant element, one that by mass makes up 8 percent of the Earth's crust. Plants and animals have evolved in an environment in which aluminum is common. In fact, aluminum is even present in the human brain. This most fundamental of organs contains, on average, 1.02 micrograms of aluminum per gram of brain tissue. Further, brain levels of aluminum increase with age, causing researchers to take a look at how that happens -- and what might be the result.
The human body absorbs aluminum from compounds in water, food, aluminum-based utensils, deodorants and drugs. But at toxic levels, aluminum can damage neurons in the brain as well as DNA within neurons. The aluminum ion can affect normal cellular reactions in the brain, cause brain inflammation and lead to neurofibrillary tangles and amyloid deposits that are the hallmark of Alzheimer's disease. In fact, aluminum chloride in combination with the sugar D-galactose injected in rats and mice induces many of the brain changes and behavioral changes seen in Alzheimer's disease.
In one important study, researchers studied the postmortem brains of 12 people with familial Alzheimer's disease in England. They found elevated aluminum content in all but one of the brain samples. The researchers also found aluminum concentrated near neurofibrillary tangles and amyloid deposits, which have been linked to Alzheimer's. They couldn't conclude that aluminum was the cause of the dementia; it may be that degenerative brain diseases concentrate and retain aluminum within the brain. Still, a connection seems clear.
The findings are alarming. Aluminum is more ubiquitous today than ever before. Aluminum hydroxide, aluminum sulfate and aluminum chloride are used in drinking water treatment and waste water management, and we use aluminum foil and aluminum in our food preparation and storage. Considering such exposure, it's important to ask questions about the potential impact.
A 15-year study in France assessed the aluminum levels in drinking water and the rate of Alzheimer's disease in multiple areas of southern France. The concentration of aluminum in the water varied from 0.001 to 0.514 mg/liter depending on location. Of the 1,677 people over the age of 65 who completed the study, 461 were diagnosed with dementia. Those whose aluminum intake was more than 0.1 mg per day had 2.26 times the risk of dementia compared with those whose intake was less than 0.1 mg per day.
All of that said, neither I nor medical science overall can provide a hard and fast answer to your question about the risk of aluminum exposure. It is heartening, however, to know that water boards measure the amount of aluminum in drinking water at a time when the correlation between human exposure to high levels of aluminum and dementia is still largely unknown.