Thursday January 7 2010
This study provides no evidence that phones slow Alzheimer's
“Mobile phone radiation ‘protects’ against Alzheimer’s,” the BBC has reported.
This story is based on research that looked at the effects of exposing genetically modified mice to the same frequency of electromagnetic field that is generated by mobile phones. These genetically modified mice were created to have some characteristics of Alzheimer’s disease. This allowed the researchers to explore whether the electromagnetic field could alter the biological processes behind an Alzheimer’s-style condition.
However, this was a small animal study and its direct relevance to mobile phone use in humans is limited. It does not provide sufficient evidence to suggest that mobile phones can protect against or cure Alzheimer’s disease.
Where did the story come from?
This research was carried out by Dr Gary Arendash at the University of South Florida. The study was funded by the National Institute on Aging, an American funding body. It was published in the peer-reviewed Journal of Alzheimer’s Disease.
The research was generally well reported by the press, which highlighted that more research would be needed in order to see the relevance to humans.
What kind of research was this?
This was an animal study looking at the effect that high-frequency electromagnetic field (EMF) had on the brains of genetically modified mice prone to Alzheimer’s-like brain changes. These potential changes included any brain impairment or changes in structure or function of the brain that are associated with Alzheimer’s.
Animal ‘models’ of human diseases are helpful for testing potential new treatments in order to establish whether they are likely to be safe and effective in humans. However, differences between these models and humans with the disease mean that the findings from models may not always reflect what will happen in humans. As this is an animal study the direct relevance to humans is likely to be limited. It is likely that further research with animals would be needed before EMF could begin to be tested as a treatment or preventative measure for Alzheimer’s in humans.
What did the research involve?
This study tested the effects of EMF on both normal mice and mice genetically modified to accumulate a protein called amyloid beta in their brains as they age. This same protein forms insoluble aggregates, or ‘clumps’, in the brains of people with Alzheimer’s disease. The study also looked at the effects of long-term exposure to EMF starting when mice were young, and exposure to EMF only once mice were older and already cognitively impaired.
To look at the effect of EMF exposure from a young age the researchers took 48 normal mice and 48 genetically modified mice aged around two months old. Each of these groups was further divided into two subgroups - a control group that would not be exposed to EMF and a treatment group that would be exposed to high-frequency EMF. The EMF was generated by an antenna placed near the cages of the exposed mice. This antenna emitted standard mobile phone frequencies for two one-hour periods per day.
The mice were given memory tests when they were aged five, six-and-a-half and nine months. The memory tasks were based on a ‘radial arm water maze’ test. This test assessed the mice’s ability to remember how to get out of a water tank using a submerged escape platform.
The researchers then looked at the effect EMF exposure had on mice at five months old, an age at which the genetically modified mice were already cognitively impaired. To do this they compared 16 normal mice and 12 genetically modified mice, once again splitting each group into two subgroups - one that would be exposed to EMF and one that would not. The mice were given memory tests at 7, 10 and 13 months old.
At the end of the experiments the researchers looked at the mice’s brain anatomy and the amount of the amyloid beta protein in their brains.
What were the basic results?
The researchers found that the genetically modified mice exposed to EMF from a young age showed less of a decline in some of the memory tasks than those that had not had this exposure. Exposing the normal mice to EMF from a young age had no effect on memory.
In the genetically modified mice that were exposed to EMF from a young age, there was no effect on amyloid beta levels or any signs associated with age-related brain damage.
Of the mice exposed to EMF from the age of five months, the normal mice that were exposed to EMF for a period of five months performed better on some memory tasks. There was an improvement in the performance of some memory tasks carried out by genetically modified mice that were exposed to EMF for eight months.
When the brain pathology was assessed in genetically modified mice that had been exposed to EMF after they were five months old, the researchers found that there was less aggregated amyloid beta protein and more soluble amyloid beta in their brains than in the brains of genetically modified mice that had not been exposed to EMF.
How did the researchers interpret the results?
The researchers suggest that their research shows that profound effects of long-term EMF exposure protect against or even reverse cognitive impairment and amyloid beta neuropathology in Alzheimer’s-like genetically modified mice. They suggest that these differences could be caused by EMF breaking down aggregates of the amyloid beta protein.
This was an animal study looking at the effect of EMF on memory and Alzheimer’s-like brain changes. However, its direct relevance to humans is limited. The researchers themselves highlight the fact that the genetically modified mice they used do not recapitulate all aspects of Alzheimer’s disease in humans, such as the accompanying death of nerve cells.
They also say that the mice were exposed to full-body EMF, and that this may have different effects and be of a different dose to the more localised exposure that mobile phone users experience.
Although it is an interesting finding that EMF may affect amyloid beta aggregation, this study does not provide sufficient evidence using a mobile phone would benefit those suffering from Alzheimer’s disease.