Dietary copper intake may be linked to Alzheimer's

Behind the Headlines

Tuesday August 20 2013

Shellfish, such as oysters, are rich in copper

The Daily Telegraph has warned that "Copper from diet 'could trigger Alzheimer's disease'," after new research has suggested that high levels of copper could disrupt the effects of a key protein in the brain.

The protein, called LRP1, is thought to be involved in helping remove amyloid beta from the brain, a protein that is strongly associated with Alzheimer's.

However, it is important to stress that the study in question involved mice bred under highly specialised conditions. It remains to be seen whether copper can trigger similar changes in the human brain.

This research certainly is not evidence that we should avoid copper-rich foods, such as red meat, shellfish, nuts, and many types of fruit and vegetables.

Low levels of copper inside the body can lead to conditions such as weakened bones (osteoporosis) and an overactive thyroid gland (hyperthyroidism).

But overall this study provides a useful basis for further research that could lead to novel targets for new drugs.

 

Where did the story come from?

The study was carried out by researchers from the University of Rochester Medical Center in New York State. It was supported by the US Alzheimer's Association, the National Institutes of Health, and the National Institute of Environmental Health Sciences.

It was published in the peer-reviewed open-access journal the Proceedings of the National Academy of Sciences (PNAS), and the article is free to read or download.

The story was covered widely by the major papers and media sources, reflecting the research community's intense interest in finding a cure for dementia.

The UK media coverage of the story was accurate, with most sources containing appropriate advice that it would be dangerous to completely remove copper from our diets.

 

What kind of research was this?

This was a laboratory study carried out in mice and human brain cells in the laboratory.

Researchers were interested in the role of copper in dementia, as previous studies suggested the balance and control of copper levels in the blood or brain are linked with the disease.

They say that early randomised trials of an agent that reduces copper levels are also "showing promise".

 

What did the research involve?

The researchers wanted to test if copper interfered with the barrier between the blood and the brain, and examine the way this barrier works. They thought that copper may make it harder for the brain to get rid of a protein linked to Alzheimer's called amyloid beta.

One of the hallmarks of Alzheimer's disease is the formation of plaques of amyloid in the degenerating brain. The researchers say increased copper levels in the plasma or brain is associated with Alzheimer's disease.

Amyloid beta is a component of the amyloid plaques found in people with Alzheimer's. It has several functions within the brain and is found in high levels in those who have the disease.

In these experiments, the researchers first bred mice genetically programmed to overproduce one of the proteins that produces amyloid beta. These mice were designed to develop Alzheimer's, or a disease similar to it, called a mouse model.

The researchers say that the type of Alzheimer's these mice developed is similar to a sporadic form of Alzheimer's in humans, and called these mice "ageing mice". They also selected control mice that were not engineered to develop the disease.

They then fed different concentrations of copper to each group and did several experiments to see what the effect was on:

  • brain cells
  • blood vessels
  • copper levels
  • inflammatory chemicals
  • various protein levels, including amyloid beta

In this way, they hoped to gain some insight into how copper is involved in preventing the clearance of amyloid beta from the brain.

Some mice, for example, were dosed with low levels of copper for 90 days, starting at two months of age. The researchers tested the behaviour of the ageing mice to see if they recognised new objects and performed other mouse tests for dementia. They also looked at their brains under the microscope and measured the levels of a range of chemicals.

 

What were the basic results?

There was a fourfold increase in copper levels in the small blood vessels of the brain in the prematurely aged mice at 25-28 months.

This increase was also linked to, or happened at the same time as, a twofold decrease in one of the proteins (LRP1) the researchers were tracking.

Amyloid beta was observed to then accumulate in the brains of the mice. The researchers say that faulty clearance of the protein from the brain to the blood may explain this.

 

How did the researchers interpret the results?

The researchers say that they have shown that the effect of copper on amyloid beta control depends on whether it is accumulating in the blood vessels or cells within the brain.

They say that these insights could help in the search for new drugs to prevent or treat Alzheimer's disease.

 

Conclusion

The findings may point to how copper could contribute to the features of Alzheimer's in mice models of the disease. However, it seems too early to say the link shows a definite cause. It also does not explain how normal levels of copper in our diet could affect the development of Alzheimer's.

It is recommended that caution is applied in interpreting these results. Other metals, such as aluminium, have also been looked at in this way and the results have been similarly inconclusive.

Instead of worrying about exposure to possible environmental factors that we have very little control over, there are other steps that can be taken to reduce the risk of developing dementia:

  • quitting smoking
  • avoiding drinking large amounts of alcohol
  • eating a healthy, balanced diet that includes at least five portions of fruit and vegetables every day
  • exercising for at least 150 minutes (2 hours and 30 minutes) every week doing moderate-intensity aerobic activity (such as cycling or fast walking), as this will improve both your physical and mental health
  • making sure your blood pressure is checked and controlled through regular health tests
  • if you have diabetes, making sure you stick to your diet and take your medication

Read more information about preventing dementia.



Analysis by
Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Analysis by Bazian

Edited by NHS Choices

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