February 22, 2011

expert reaction to paper on mobile phones and brain metabolism

Research suggested a potential link between mobile phone use and increased brain metabolism.

Professor Patrick Haggard, Institute of Cognitive Neuroscience at University College London, said:

“This study reports a 7% increase in brain metabolism close to the antenna of a commercial mobile phone during transmission, compared to when the phone is off. It is not the first study to report such effects, but it is considerably larger than any of the previous studies, including many more participants.

“This is a very interesting result, since it suggests a possible direct effect of mobile phone signals on brain function. However, the result should be treated with some caution. First, independent replication of results in a different laboratory is generally considered very important in this area of research. Second, it would be useful to know whether participants could tell if the phone was on or off. Simply knowing that the phone is on could influence brain activity, so the results can only definitively be attributed to the mobile phone signals if this can be ruled out.

“Third, as the authors point out, the implications for health remain unclear. Much larger fluctuations in brain metabolic rate occur naturally, for example during thinking. However, if further studies confirm that mobile phone signals do have direct effects on brain metabolism, then it will be important to investigate whether such effects have implications for health.”

Professor Malcolm Sperrin, Director Of Medical Physics and Clinical Engineering at Royal Berkshire Hospital, said:

“This paper is particularly interesting in that it reports an increase in brain metabolism as a result of the use of mobile phones. The causality is important since a direct link is reported as opposed to coincidental events which may have an independent origin. The authors and institution where the research was carried out are all of the highest calibre and the paper is written in an authoritative manner.

“The fact that there is an increase in metabolism as a result of phone use is not claimed to be clinically significant; more work is required to establish any possible link between RF energy deposition in the brain and a consequential health risk. It is reasonable to assume that the small increase in metabolism results from a deposition of energy, which may result in turn from local temperature changes or perhaps magnetic or electrical stimulation that does not involve heat at all. Furthermore, it is known that sensory input (e.g. hearing) does elevate brain metabolism although the asymmetric nature of the finding does suggest that this is not the case here.

“It is important to fully appreciate that no health risk is identified in this paper.”

Effects of Cell Phone Radiofrequency Signal Exposure on Brain Glucose Metabolism, by Nora D Volkow et al., published in the Journal of the American Medical Association at 15.00 CT (21.00 UK time) on Tuesday 22 February 2011.