Authors
Stovner LJ, Oftedal G, Straume A, Johnsson A. (2008). Nocebo as headache trigger: evidence from a sham-controlled provocation study with RF fields. Acta Neurol Scand Suppl 188:67-71.

Background
Reports in the late 1990’s on the health effects of mobile phone use included head discomfort or headache among the list of complaints.  A 2005 review, as well as three subsequent studies, failed to find an association between radiofrequency (RF) fields emitted from mobile phones and headaches. 

Objective
The objective of this research was to describe in greater detail the types of headaches experienced by mobile phone users.

Methods
The study was set in Norway.  Volunteers with a history of headaches associated with mobile phone use were invited to participate in the study.  Seventeen subjects (12 men, 5 women) aged between 20 and 58 years were included.  Subjects participated in a maximum of 4 ‘trials’ consisting of 30 minutes of RF exposure and 30 minutes of sham- exposure, in random order, with at least 2 days interval between exposures.  The exposure system consisted of 2 antennae, with only one emitting a RF field during RF exposure.  Throughout the experiment, neither the subjects nor the researchers knew which signal (RF or sham) had been emitted from the antenna so that this knowledge could not influence their responses.  Before, during, and after each exposure, subjects answered questions on the timing, degree, and location of symptoms.  Subjects also described their usual headache symptoms, both related to mobile phone use and other headaches, and were examined by a neurologist.

Results
Both RF and sham exposures induced the same number and types of headaches among subjects.  Pain developed in nearly half of all exposures, was most often localized to the temple, ear, or face, and was only on one side of the head in two-thirds of exposures.  These symptoms experienced in the study were similar to those that regularly occurred with mobile phone use in these subjects.  Subjects reported that their mobile phone-associated headaches were mild and occurred from always to less frequently than every third call.  The mobile-phone associated headaches were diagnosed by a neurologist in 16 of the subjects as a frequent episodic tension-type headache (TTH).  Sixty-five percent of the subjects experienced headaches not related to mobile phone use, which is similar to what is found in the general population.  These headaches were TTH or migraine headaches with a frequency ranging from daily to 1-4 days/month.

Interpretation
This study found no association between exposure to RF fields and headaches in people who normally report headaches triggered by mobile phone use.  The authors propose that the pain experienced by subjects could be the result of anticipating or expecting a negative outcome, referred to as the nocebo effect.  These fears of adverse health effects could be caused by widespread media coverage in Norway of headaches caused by mobile phone use.

Conclusion
There is no evidence that RF fields emitted by mobile phones cause headaches.  Headaches associated with mobile phone use may be caused by fear of this adverse health effect.


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