Study Suggests Iron Is at Core of Alzheimer’s Disease
Researchers focus on iron accumulation in the brain (August 20)
Most researchers believe that Alzheimer’s disease (AD) is caused by one of two proteins — tau and beta-amyloid. As we age, most scientists say, these proteins either disrupt signaling between neurons or simply kill them.
Now, a study from the University of California–Los Angeles suggests a third possible cause: iron accumulation. The new findings were published in the August edition of the Journal of Alzheimer’s Disease.
Dr. George Bartzokis, the study’s senior author, and his colleagues used a magnetic resonance imaging (MRI) technique that can measure the amount of brain iron in ferritin, a protein that stores iron, in 31 patients with AD and in 68 healthy control subjects.
In the AD patients, the researchers compared the hippocampus, which is known to be damaged early in the disease, and the thalamus, an area that is generally not affected until the later stages. They found that iron is increased in the hippocampus and is associated with tissue damage in that area; but increased iron was not found in the thalamus.
While most AD researchers focus on the buildup of tau or beta-amyloid that results in the signature plaques associated with the disease, Bartzokis has long argued that the breakdown begins much further “upstream.” The destruction of myelin, the fatty tissue that coats nerve fibers in the brain, he says, disrupts communication between neurons and promotes the buildup of amyloid plaques. These plaques in turn destroy more and more myelin, disrupting brain signaling and leading to cell death and the classic clinical signs of AD.
Myelin is produced by cells called oligodendrocytes. These cells, along with myelin, have the highest levels of iron of any cells in the brain, Bartzokis says, and circumstantial evidence has long supported the possibility that brain iron levels might be a risk factor for age-related diseases, such as AD. Although iron is essential for cell function, too much of it can promote oxidative damage, to which the brain is especially vulnerable.
Bartzokis reports that medications that chelate and remove iron from tissue are being developed by several pharmaceutical companies as treatments for AD. MRI technology may allow doctors to determine who is in greatest need of such treatments, he says.
Source: UCLA; August 20, 2013.