June 25, 2019

Will your cellphone really make you grow 'head horns'? Here's the science behind the viral news story.

Daily Briefing

    The media last week caught wind of a series of studies that suggested cellphones were causing young people to grow hornlike bone spurs from the back of their skull, but experts caution that the study's findings have been overhyped.

    Cheat sheet series: Evidence-based medicine 101

    Study details

    For the first study, published in the Journal of Anatomy in 2016, two researchers from the University of the Sunshine Coast in Australia, looked at 218 X-rays of patients ages 18 to 30. The findings suggested that a hornlike bone growth could be found in 41% of young adults. The feature was found to be more prevalent in men than women.

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    These bone spurs, called external occipital protuberances [EOPs], are caused by tilting the head forward, which shifts weight from the spine to the muscles at the back of the skull. This can cause bone growth within the tendons and ligaments.

    In a second study, published in Clinical Biomechanics in 2018, the same two researchers shared a case study involving four teenagers that they said demonstrated the so-called "head horns" weren't caused be genes but rather mechanical load on the muscles in the skull and neck.

    And in another paper published in Scientific Reports in 2018, the researchers looked at 1,200 X-rays of patients in Queensland, Australia, between the ages of 18 and 86, and found the size of the bone growth, which was present in 33% of the population, decreased with age.

    The researchers then looked at recent developments from the past 20 or so years to understand why younger people may be posturing their bodies differently.

    This led the researchers to suggest handheld devices like smartphones could be to blame. David Shahar, co-author of the papers and a chiropractor, said, "People are more sedentary; they put their head forward, to look at their devices. That requires an adaptive process to spread the load."

    The researchers did acknowledge, however, that they "have not ever drawn direct links between the presence of [EOP] and mobile technology use." Instead, Shahar said, "we have suggested that the cause appears to be a mechanical one" linked to a position that's "often associated with the use of mobile technologies."

    However, the researchers also noted there could be other explanations for the EOPs, including poor posture "while sitting, standing, or sleeping … bike riding using drop hand-bars," or "sleeping supine with a high pillow."

    What the experts say

    Many experts were critical of the findings and the media hype around it, especially the supposed link between the EOPs and cellphone usage. Michael Nitabach, a professor of physiology, genetics, and neuroscience at Yale University, said, "Without knowing about the cell phone use of any of the people whose head X-rays were analyzed, it is impossible to draw conclusions about correlation between cell phone use and skull morphology."

    David Putrino, director of rehabilitation innovation at Mount Sinai Health, said the connection between neck posture and the bone spurs appeared to be legitimate. But, he added, "I don't think we're at a point yet where we can blame this on cellphone use."

    David Langer, chair of neurosurgery at Lenox Hill Hospital, said the study "doesn't make a bit of sense" to him. "You're more likely to get degenerative disc disease or misalignment in your neck than a bone spur growing out of your skull," he said. "I haven't seen any of these, and I do a lot of X-rays. I hate being a naysayer off the bat, but it seems a little bit far-fetched. Head horns? Come on."

    Other experts said the bone spurs may be legitimate, but not something to be concerned about.

    Evan Johnson, an assistant professor and director of physical therapy at NewYork-Presbyterian Och Spine Hospital, said bending your neck forward for long periods of time could potentially cause a bone spur to form. But, he said, it's likely not dangerous. "The fact that you have this little bony projection in your skull, that means nothing."

    John Hawks, a paleoanthropologist at the University of Wisconsin, said EOPs are "a well-studied trait in anthropology, and we know a lot about its frequency in different populations. This paper cites none of that." Hawks added, "Men have [EOPs] more often than women, so much so that this is one of several traits that help forensic scientists establish whether a skeleton belonged to a male or female individual."

    Nivien Speith, from the University of Derby, said he's seen a number of "enlarged EOPs in the early Medieval skulls [he's] studied—male ones mostly." He added, "It could be genetic, or even just a simple bony outgrowth that has unknown etiology. Often, they can occur through trauma to the area as well."

    Until more research is done, Hawks said the panic over cellphone use isn't necessary. "I'm seeing people forwarding this link who are justifying their own belief that parents should limit screen time for kids," he said. "Same old stuff that drives stories about evil devices."

    The study researchers were not available for comment when the New York Times reached out (Grady, New York Times, 6/20; Killgrove, Forbes, 6/20; Stanley-Becker, Washington Post, 6/20; Woodward, Business Insider, 6/21).

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