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Study links cellphone usage to metabolism in brain cells

Doesn’t shed new light on risks of brain cancer

Research shows an increase in brain cells’ metabolism of sugar in the part of the brain closest to the phone antenna. Research shows an increase in brain cells’ metabolism of sugar in the part of the brain closest to the phone antenna. (David L. Ryan/Globe Staff/File)
By Deborah Kotz
Globe Staff / February 23, 2011

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Using a cellphone while driving can be a distracting hazard, but it turns out that simply pressing a cell phone to your ear can cause temporary changes in the brain, according to new research published yesterday by the Journal of the American Medical Association.

The study suggests that cellphones have a subtle effect on brain cells, but does not shed further light on whether cellphones increase the risk of brain cancer, a subject of fierce debate among researchers. Nor does it link cellphone use to any other brain abnormality.

What it does show, however, is that cellphones lead to a temporary increase in brain cells’ metabolism of sugar, or glucose, in whatever part of the brain that’s closest to the cellphone antenna. The research is the first of its kind to look at that particular area of brain function with regard to cellphone use.

“It’s not a dramatic increase,’’ said study author Dr. Nora Volkow, director of the National Institute on Drug Abuse. “It’s more in the range of the brain activation that occurs in, say, the language center when you’re speaking.’’

The study was conducted on 47 healthy volunteers who agreed to undergo brain scanning with Positron Emission Tomography — an imaging test that measures cells’ uptake of glucose — while a cellphone connected to a muted call was attached to the right ear for 50 minutes. The PET scan showed about a 7 percent increase in glucose metabolism in brain regions nearest to the cell phone antenna.

“I wish my study could enlighten brain cancer risks,’’ added Volkow. “But we don’t know whether activation from cellphones could be negative, or even whether it could be beneficial.’’

Some 91 percent of Americans use cellphones, averaging 21 minutes a day with a phone — or Bluetooth device — pressed to their ears. The electromagnetic radiation emitted by such devices appears to activate brain cells and increase their metabolism.

“Even though the health consequences of these effects on brain glucose metabolism are unknown, the results point to a conclusion that cell phone use can possibly affect brain function,’’ wrote the authors of an editorial that accompanied the study. “The results warrant further investigation.’’

Previous population studies of cellphone use and brain cancer risk have come to contradictory conclusions. The latest research published last year in the International Journal of Epidemiology found that overall, cellphone users have no heightened risk for two of the most common types of brain tumors, glioma and meningioma. But a small group of study participants who spent the most time on cellphones did have some increased risk of glioma.

The latest finding is enough to warn Volkow off of holding her cellphone directly to her ear. Since seeing the study results, she said she’s only using her cell on speaker or with wired ear pieces to keep the antenna away from close contact with her brain.

Bluetooth devices also emit electromagnetic radiation, as do cordless phones found in many homes.

“I’m conservative when it comes to my brain. I figure, why not play it safe?’’ she said. Children, she added, should be particularly careful about cellphone use since their brains are still developing. “I’m more willing to make a recommendation to encourage kids and teens to use the speaker or an ear piece.’’

Other experts, though, aren’t convinced that there’s enough evidence to warrant changing cellphone habits.

“This finding is of unknown clinical importance and isn’t going to change what I do,’’ said Dr. Dimitrios Trichopoulos, a professor of cancer prevention and epidemiology at Harvard School of Public Health. “Overall, in terms of health effects, I don’t think there’s cause for concern.’’

Deborah Kotz can be reached at dkotz@globe.com.