Scientists say copper may contribute to the development of Alzheimer’s disease, a degenerative brain disorder that causes dementia and eventually death.
Alzheimer’s disease is a leading cause of dementia worldwide in people ages 65 and older. According to the organization Alzheimer's Disease International, almost 36 million people were living with dementia globally in 2010, and the number is projected to rise to 115 million by 2050.
Alzheimer’s is caused by the toxic accumulation of a protein called amyloid beta. Amyloid beta forms plaques in the brain that are the hallmark of the disease. But the mechanism underlying the collection of the protein is unknown.
Now, researchers have concluded that one of the main environmental triggers of Alzheimer’s disease appears to be copper, an important metal that is in meat, fruits and vegetables as well as drinking water. Copper plays an important role in nerve conduction, bone growth and hormone secretion.
Rashid Deane is a professor of neurosurgery at the University of Rochester Medical Center in New York.
According to Deane, copper accumulates in the brains of those with Alzheimer’s, contributing to the collection of beta amyloid, normally swept away in healthy individuals by a protein called LRP1, which Deane likens to a garbage truck.
“It looks like in the copper-dosed animals that are aging, the capacity to remove the toxin amyloid from the brain is reduced in these animals because there isn’t so many garbage trucks to take it away," said Deane.
Researchers led by Deane fed copper-laced drinking water to mice for three months. Investigators found the copper in the blood stream made its way to the walls of capillaries that protect the brain from toxins, including copper.
Over time, Deane says, the copper broke down the so-called blood-brain barrier that prevents harmful substances, such as copper, from entering and harming the brain. Researchers noted the same effect in human brain cells.
The mystery is why copper collects in the brains of some individuals, potentially causing Alzheimer’s disease, and not in others.
Deane says those who develop Alzheimer’s are at risk because of genetics as well as their body's ability to prevent damage to cells. And then there’s the impact of modern life.
“Humans live in different places sometimes over their lives, they eat things, they try different foods. And some people are very conscious in what they are eating now because they are wise about the composition of the food and they know the nutritional value of the food they are eating. So, that may be one variable component which may tend to explain why it develops," said Deane.
Because copper is in everything, other researchers say trace amounts are unlikely to account for the epidemic of Alzheimer's disease. An article on copper's potential role in Alzheimer's disease is published in the journal Proceedings of the National Academy of Sciences.