Holding a cell phone to your ear for a
long period of time increases activity in parts of the brain close to
the antenna, researchers have found.
Glucose metabolism — that’s a measurement of how the brain uses energy — in these areas increased significantly when the phone was turned on and muted, compared with when it was off, Dr. Nora Volkow, director of the National Institute on Drug Abuse, and colleagues reported in the Journal of the American Medical Association.
“Although we cannot determine the clinical significance, our results give evidence that the human brain is sensitive to the effects of radiofrequency-electromagnetic fields from acute cell phone exposures,” co-author Dr. Gene-Jack Wang of Brookhaven National Laboratory in Long Island, where the study was conducted, told MedPage Today.
What we know about Cell Phones and Cancer
Although the study can’t draw conclusions about long-term implications, other researchers are calling the findings significant.
“Clearly there is an acute effect, and the important question is whether this acute effect is associated with events that may be damaging to the brain or predispose to the development of future problems such as cancer as suggested by recent epidemiological studies,” Dr. Santosh Kesari, director of neuro-oncology at the University of California San Diego, said in an e-mail to MedPage Today and ABC News.
There
have been many population-based studies evaluating the potential links
between brain cancer and cellphone use, and the results have often been
inconsistent or inconclusive.
Most recently, the anticipated Interphone study was interpreted as “implausible” because some of its statistics revealed a significant protective effect for cell phone use. On the other hand, the most intense users had an increased risk of glioma — but the researchers called their level of use “unrealistic.”
But few researchers have looked at the actual physiological effects that radiofrequency and electromagnetic fields from the devices can have on brain tissue. Some have shown that blood flow can be increased in specific brain regions during cell phone use, but there’s been little work on effects at the level of the brain’s neurons.
So Dr. Volkow and colleagues conducted a crossover study at Brookhaven National Laboratory, enrolling 47 patients who had one cell phone placed on each ear while they lay in a PET scanner for 50 minutes.
The researchers scanned patients’ brain glucose metabolism twice — once with the right cell phone turned on but muted, and once with both phones turned off. There was no difference in whole-brain metabolism whether the phone was on or off.
Are cell phones Dangerous for kids?
But
glucose metabolism in the regions closest to the antenna — the
orbitofrontal cortex and the temporal pole — was significantly higher
when the phone was turned on.
Further analyses confirmed that the regions expected to have the greatest absorption of radiofrequency and electromagnetic fields from cell phone use were indeed the ones that showed the larger increases in glucose metabolism.
“Even though the radio frequencies that are emitted from current cell phone technologies are very weak, they are able to activate the human brain to have an effect,” Dr. Volkow said in a JAMA video report.
The effects on neuronal activity could be due to changes in neurotransmitter release, cell membrane permeability, cell excitability, or calcium efflux. It’s also been theorized that heat from cell phones can contribute to functional brain changes, but that is probably less likely to be the case, the researchers said.
Dr. Wang noted that the implications remain unclear — “further studies are needed to assess if the effects we observed could have potential long-term consequences,” he said — but the researchers have not yet devised a follow-up study.
“The take-home message,” Dr. Kesair said, “is that we still don’t know, more studies are needed, and in the meantime users should try to use headsets and reduce cell phone use if at all possible. Restricting cell phone use in young chinldren certainly is not unreasonable.”
Glucose metabolism — that’s a measurement of how the brain uses energy — in these areas increased significantly when the phone was turned on and muted, compared with when it was off, Dr. Nora Volkow, director of the National Institute on Drug Abuse, and colleagues reported in the Journal of the American Medical Association.
“Although we cannot determine the clinical significance, our results give evidence that the human brain is sensitive to the effects of radiofrequency-electromagnetic fields from acute cell phone exposures,” co-author Dr. Gene-Jack Wang of Brookhaven National Laboratory in Long Island, where the study was conducted, told MedPage Today.
What we know about Cell Phones and Cancer
Although the study can’t draw conclusions about long-term implications, other researchers are calling the findings significant.
“Clearly there is an acute effect, and the important question is whether this acute effect is associated with events that may be damaging to the brain or predispose to the development of future problems such as cancer as suggested by recent epidemiological studies,” Dr. Santosh Kesari, director of neuro-oncology at the University of California San Diego, said in an e-mail to MedPage Today and ABC News.
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Most recently, the anticipated Interphone study was interpreted as “implausible” because some of its statistics revealed a significant protective effect for cell phone use. On the other hand, the most intense users had an increased risk of glioma — but the researchers called their level of use “unrealistic.”
But few researchers have looked at the actual physiological effects that radiofrequency and electromagnetic fields from the devices can have on brain tissue. Some have shown that blood flow can be increased in specific brain regions during cell phone use, but there’s been little work on effects at the level of the brain’s neurons.
So Dr. Volkow and colleagues conducted a crossover study at Brookhaven National Laboratory, enrolling 47 patients who had one cell phone placed on each ear while they lay in a PET scanner for 50 minutes.
The researchers scanned patients’ brain glucose metabolism twice — once with the right cell phone turned on but muted, and once with both phones turned off. There was no difference in whole-brain metabolism whether the phone was on or off.
Are cell phones Dangerous for kids?
But
glucose metabolism in the regions closest to the antenna — the
orbitofrontal cortex and the temporal pole — was significantly higher
when the phone was turned on.Further analyses confirmed that the regions expected to have the greatest absorption of radiofrequency and electromagnetic fields from cell phone use were indeed the ones that showed the larger increases in glucose metabolism.
“Even though the radio frequencies that are emitted from current cell phone technologies are very weak, they are able to activate the human brain to have an effect,” Dr. Volkow said in a JAMA video report.
The effects on neuronal activity could be due to changes in neurotransmitter release, cell membrane permeability, cell excitability, or calcium efflux. It’s also been theorized that heat from cell phones can contribute to functional brain changes, but that is probably less likely to be the case, the researchers said.
Dr. Wang noted that the implications remain unclear — “further studies are needed to assess if the effects we observed could have potential long-term consequences,” he said — but the researchers have not yet devised a follow-up study.
“The take-home message,” Dr. Kesair said, “is that we still don’t know, more studies are needed, and in the meantime users should try to use headsets and reduce cell phone use if at all possible. Restricting cell phone use in young chinldren certainly is not unreasonable.”