Copper Associated with Alzheimer's Disease

Copper ups the risk of Alzheimer's disease by preventing the body from clearing the toxic compound from the brain, a new study reported. Researchers also found that copper accumulates in the brain and weakens the blood-brain barrier.

The study was conducted by researchers at the University of Rochester Medical Center and their colleagues. The team found that copper accelerates the accumulation of toxic amyloid beta in the brain.

"It is clear that, over time, copper's cumulative effect is to impair the systems by which amyloid beta is removed from the brain. This impairment is one of the key factors that cause the protein to accumulate in the brain and form the plaques that are the hallmark of Alzheimer's disease," said Rashid Deane, Ph.D., a research professor in the University of Rochester Medical Center (URMC) and the lead author of the study. 

For the study, researchers used human and mice brains to understand the mechanism through which copper promotes Alzheimer's disease.

Alzheimer's disease is an irreversible and progressive brain disease that slowly destroys memory and thinking skills which in turn leads to the affected person being unable to carry out simple tasks essential for daily living. In most people with Alzheimer's, symptoms first appear after age 60.

Dietary copper comes from tap water, meat, shellfish as well as fruits and vegetables. Copper is required to stimulate bone growth, nerve conduction and hormone release. The latest study showed that excess amount of copper can disrupt the blood-brain barrier that results in build-up of amyloid beta. The blood-brain barrier is a system that regulates the entry and exit of compounds in the brain.

Lipoprotein receptor-related protein 1 (LRP1) removes excess amount of amyloid beta under normal conditions, researchers said.

The team found that excess amount of copper prevented LRP1 from removing amyloid beta from the brain which resulted in the protein disrupting brain function.

In the study, researchers had fed mice water with normal levels of copper. "These are very low levels of copper, equivalent to what people would consume in a normal diet." said Deane.

They found that mice models that had developed Alzheimer's disease had a leaky blood-brain barrier that could no longer control the movement of compounds. As a result, copper and other metal ions were freely moving in the brain.

Copper ions also joined with the toxic proteins to create a plaque that impaired the functions of the brain. In addition, copper promoted inflammation in the brain that led to the breakdown of the blood-brain barrier.

The scientists also added that further research is needed to understand how copper affects development of Alzheimer's disease.

"Copper is an essential metal and it is clear that these effects are due to exposure over a long period of time," said Deane, according to a news release. "The key will be striking the right balance between too little and too much copper consumption. Right now we cannot say what the right level will be, but diet may ultimately play an important role in regulating this process."

The study is published in the journal Proceedings of the National Academy of Sciences.