For the first time researchers have found that excess iron in the brain may lead to the development of Alzheimer's disease, according to a study published in the August issue of the Journal of Alzheimer's Disease. The findings, researchers say, bring the medical community closer to understanding the condition -- which is the sixth leading cause of death among Americans.
It was long held that two proteins, tau and beta-amyloid, triggered Alzheimer's disease. Imaging studies on the brains of patients revealed tissue damage along with protein deposits in the hippocampus region of the brain, where memories are funneled.
The buildup of defective tau or beta-amyloid proteins in this region results in the signature plaques associated with the disease, which destroy tissue and disrupt signaling between brain neurons.
Although these damaged proteins showed up in MRI images of people with the illness, their presence alone did not provide a complete understanding of the disease, Dr. George Bartzokis, a professor of psychiatry at the University of California, Los Angeles, and senior author of the new study, told Al Jazeera. "We still weren't aware of what was causing damage to these proteins."
The UCLA study provided the missing link.
Scientists examined the hippocampus and thalamus regions of the brain. MRI results revealed that in the hippocampus region, the interaction of iron with amyloid proteins resulted in their toxicity. The thalamus showed no such increase in iron levels or signs of tissue damage.
Thirty-one patients with Alzheimer's and 68 healthy control subjects participated in the study.
Scientists concluded that the deadly combination of these proteins along with high levels of iron created a toxic environment in the brain that led to Alzheimer's disease. "The accumulation of amyloid is like gasoline, while excess iron is the flame," Bartzokis said. "An excess of iron is destructive because it is a pro-oxidant metal, meaning it converts free radicals into highly reactive ones."
The reason our brains accumulate iron as we age has to do with myelin, an insulating layer that forms around nerves in the brain. "Myelin requires a lot of iron, and as we get older, more and more iron gets deposited, which promotes free radical damage," Bartzokis said. "Once we reach old age, we have an awful lot of it floating around and the same process that kept your mind functioning now begins to undermine you. Now the environment in your brain is toxic."
Alzheimer's disease is the most common form of dementia and is characterized by the loss of memory and other cognitive abilities serious enough to interfere with daily life, according to The Alzheimer's Association.
An estimated 5.2 million Americans suffer from Alzheimer's disease and numbers are expected to increase as the U.S. population ages. By 2025, the number of Americans aged 65 and older with the illness is expected to grow by 40 percent unless a cure is found.
Excess iron can be prevented by lifestyle adjustments. Consuming less red meat, which is abundant in iron, and staying away from iron supplements for those who are not iron deficient goes a long way, Bartzokis said.
"If you look at any multivitamin, they all have iron included," he lamented. "As if everyone is walking around with an iron deficiency."
"People are walking around with little destructive bombs in their bodies," he added.
Bartzokis believes that iron supplements should be made available only by prescription. "Iron takes years to accumulate," he said. "People take vitamins as if more is better, but it may actually be worse."
"Young people need iron for brain development, but once you're going into middle age, you have to really think about what vitamins you're taking and whether they're doing you any good," he added. "The problem with taking metals is that the body has no way of eliminating the excess other than bleeding."
Individuals who suspect that they may suffer from iron deficiency should check with their doctors before taking supplements, Bartzokis said.