WASHINGTON: A study has found that copper in the blood might damage a molecule that rids the brain of a substance called amyloid beta, which builds up in toxic quantities in the brains of people with Alzheimer's disease.

The study, led by Rashid Deane, PhD at the University of Rochester Medical Centre, demonstrated one way in which copper might contribute to the development of the Alzheimer's disease.

"Metals like aluminium have been suspected for years, but the mechanism through which metals might act has been unclear," Deane said.

"We've demonstrated one mechanism through which copper increases levels of amyloid beta in the brain, by damaging the molecule that gets rid of the substance," he said.

The study was done in mice as well as on cells from the brains of people who died from Alzheimer's disease.

In the study, the researchers compared mice that drank water containing trace amounts of water (.12 milligrams per litre, less than one-tenth the 1.3 mg/l level of copper allowed in drinking water by the Environmental Protection Agency), to mice that drank distilled water.

The analysis of the study found that mice that drank water with trace levels of copper had about twice as much copper in the cells lining the blood vessels of the brain as the mice that did not.

After 10 weeks, they also had about one-third fewer LRP molecules in those blood vessels and about one-third more amyloid beta in their brains than the control mice.

Using human cells, the team discovered that copper damaged the protein LRP to such an extent that it stopped working.

In the study, it was also found that copper damaged a molecule known as LRP (low-density lipoprotein receptor-related protein), a molecule that acts like an escort service in the brain, shuttling amyloid-beta out of the brain and into the body.

"We all have some amyloid beta in the brain normally," said Deane.

"When you age, a little bit more accumulates in the brain naturally. But the process is greatly accelerated in people with Alzheimer's disease," he added.

From the finding, Deane emphasized that having appropriate levels of copper in human body was crucial for health as copper helps keep bones strong and skin toned, and it helps nerves fire crisply.

He added that while drinking water was the most obvious source of copper in the diet, because of copper pipes, the substance was also quite common in red meat, nuts, shellfish, and many fruits and vegetables.

The research highlighted the importance of the blood-brain barrier, an intricate filtering mechanism that lines the inside of blood vessels inside the brain and is designed to keep toxic substances out.

"The body needs to maintain the environment of the brain pristinely so that our brain cells stay healthy and are able to function effectively," said Deane.

"It's the job of the blood-brain barrier to keep the brain safe and healthy. It may very well be a breakdown with the barrier that is at the root of Alzheimer's disease," he said.