The rise of cell phone use worldwide has raised questions about the effect of cell phone electromagnetic radiation (EMR) on the brain. It’s reassuring that cell phone EMR consists of non-ionizing radiation, which is unlikely to cause cell mutation. However, questions still persist about whether EMR can cause brain injury or cancer.Some studies have shown a slight correlation between cell phone use and the prevalence of brain tumors. But the issue is unresolved because of inconsistent findings. Now for the first time, a study published in the Journal of the American Medical Association (JAMA) describes the impact of cell phone EMR on regional activity of the brain.EMR from cell phones had previously been shown to be absorbed in the brain. Although the radiation emitted by cell phones is very low, the frequencies could interfere with brain function. Prior studies of cerebral blood flow in response to EMR have been inconsistent, reporting increases, decreases and increases, or no changes at all. But until the JAMA article, no studies had examined the effect on brain function in humans.In the JAMA study, healthy subjects were selected that had their brain function studied by positron emission tomography (PET) scan during cell phone exposure. PET is able to measure the uptake of glucose in the brain, a measure of metabolic activity.The study found that the human brain is sensitive to the effects of EMR from cell phone exposure. PET study of regions closest to the antenna during cell phone exposure suggests that EMR is absorbed by brain tissue and increases local brain activity. This finding is consistent with previous studies of the effect of transcranial magnetic stimulation (a strong magnetic field placed near the skull) on brain excitation used to treat depression.So what happened in the brain? EMR increased neuron excitability or had a thermal (heat) effect on brain tissue. Still, measured increases in regional metabolism are only about 7%. Such increases are trivial when compared to the effect of visual stimulation on brain metabolism, reported to be up to 51% in other studies.The JAMA study results provide evidence that cell phone exposure affects brain metabolic activity. However, these results provide no evidence that repeated cell phone use can cause cancer. Further studies are needed to assess whether cell phone EMR has potential long-term harmful consequences. See All House Calls by Dr. Geehr.