When you engage in a long cell phone conversation, a new study says, the phone radiation may increase the brain activity in regions nearest to the antenna. It's the newest entry into the long-running debate about whether cell phones carry health risks, but the scientists behind the research in the Journal of the American Medical Association caution that they don't know what this localized change in brain activity means—or even how it's happening. Many previous studies of cell phone safety have looked into the question of whether the phones' radiation could cause cancer (there's no solid evidence that it could) or looked at the effects of the heat that phones create. But Nora Volkow and colleagues investigated something else: The metabolism of the brain regions nearest to the phone—that is, how quickly they are burning energy. To do it, Volkow's team recruited 50 people and subjected them to PET scans while an active cellphone sat next to their heads.
To blind the participants, the authors strapped two cell phones on their heads, one to each ear (the cellphone used in this work is a standard Samsung CDMA flip phone). Both were kept muted, and only one was activated by a call—the side that was activated was flipped in two different recording sessions. The calls started 20 minutes before a dose of radioactive glucose, and kept going for a half an hour afterwards to provide a long-term picture of metabolic activity. The data from one of the subjects ended up not being used because the cell company dropped the call. [Ars Technica]
The PET scans
tracked that radioactive glucose to monitor the brain's metabolism. They found no appreciable difference across the whole brain between people undergoing long cell conversations and those not talking on the phone. But they found a 7 percent increase in energy use in the brain regions right next to an active phone.
Brain imaging physicist Dardo Tomasi of Brookhaven National Laboratory, who co-authored the study, said that’s several times less activity than visual brain regions show during an engaging movie. “The effect is very small, but it’s still unnatural. Nature didn’t prepare our brains for this,” Tomasi said. [Wired]
Still, Volkow and Tomasi aren't sure what exactly their study is showing. The heightened activity would suggest neurons
are firing a little faster in these regions, but they don't know the mechanism by which cell radiation could engineer this boost. In addition, while the study's result sounds scary, there is not yet even evidence that the localized brain effect is bad news.
Volkow says it is too early to tell whether this is good or bad for the brain. "Much larger fluctuations in brain activity occur naturally," says Patrick Haggard at University College London. In fact, being able to increase activity might boost the brain's connectivity, and could even be useful therapeutically, Volkow suggests. [New Scientist]
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