Does Your Cell Phone Give You Headaches? Not Likely
Abstract & Commentary
By Dara G. Jamieson, MD, Associate Professor, Clinical Neurology, Weill Medical College of Cornell University. Dr. Jamieson is a consultant for Boehringer Ingelheim and Merck, and is on the speaker's bureau for Boehringer Ingelheim, Merck, Ortho-McNeil, and Pfizer.
Synopsis: No evidence was found to indicate that people with self-reported sensitivity to mobile phone signals are able to detect such signals or that they react to them with increased symptom severity.
Source: Rubin GJ, et al. Are Some People Sensitive to Mobile Phone Signals? Within Participants Double Blind Randomized Provocation Study. BMJ. 2006. Epub ahead of print.
The label of electromagnetic hypersensitivity (EHS) is given to individuals who report non-specific symptoms that are perceived to be related to electrical devices, including cell phones, visual display units, and power lines. Surveys of susceptible individuals with EHS ascribe a multitude of complaints to electromagnetic field (EMF) exposure, including headaches, sleep disorders, dizziness, fatigue, and tension. (Al-Khlaiwi T, Meo SA. Saudi Med J. 2004:25:732-736. Roosli M, et al. Int J Hyg Environ Health. 2004;207:141-150). A review of the literature published between 2000 and 2004 evaluated 13 observational or experimental studies of exposure to EMF (Seitz H, et al. Sci Total Environ. 2005;349:45-55). Results of randomized cross-over studies were contradictory. No causal relationship was noted in a provocation study of purportedly sensitive individuals. Results of studies of the association between EMF exposure and headache were mixed. Further investigation was suggested.
Rubin and colleagues performed a double-blind, randomized, within-participants provocation study in London to test whether people who reported sensitivity to mobile phone signals had more symptoms when exposed to a pulsing mobile signal than when exposed to a sham signal or non-pulsing signal. Sixty sensitive people who reported headache-like symptoms within 20 minutes of using a 9000 MHz global system for mobile communication (GSM) mobile phone were compared to 60 control participants who denied any symptoms related to mobile phone use. Conditions for 3 exposures, GSM signal, an unpulsed continuous wave signal, and sham without signal, were exactly the same for 50 minutes with an antenna mounted above and behind the left ear. Each participant was randomly administered the exposure in a blinded fashion in 3 separate sessions. Questionnaires about subsequent symptoms, with visual analogue scale measures, were administered at the end of the exposure and 24 hours later. The participants were also asked to state their degree of confidence that a particular exposure had taken place. Statistical calculations including 2-way analysis of variance and generalized estimating equations found no evidence that self-reported sensitivity to the mobile phone signals was correlated to reported symptoms. Headache severity increased during exposure and decreased immediately afterwards without correlation between exposure conditions and symptom severity. The proportion of sensitive participants who believed a signal was present during GSM exposure (60%) was similar to the proportion that believed one was present during sham exposure (63%). Rubin et al note that as sham exposure was sufficient to trigger severe symptoms in sensitive participants, psychological factors may have an important role in purported sensitivity to mobile phones.
The psychological factors linked to headaches are notable by the high rate of placebo effects from multiple types of interventions. This scientifically rigorous study debunks the notion that use of a mobile phone might trigger headaches due to EHS exposure. It also illustrates the importance of the nocebo effect on headaches, and requires that epidemiological studies of headache causation be carefully designed to take this factor into consideration. Patients who report sensitivity to mobile telephone use should be encouraged to seek alternative explanations for their headache symptoms.