The mobile truth of cellular phones

 In brain injury, cognitive science

save-brain2.jpgDoes talking in your mobile phone influence the workings of your brain? Yes, claims a new study in Neuropsychologia of healthy volunteers. But it’s not only bad, it seems; some cognitive functions become better during mobile phone radiation.

Mobile phone radiation and health concerns have been raised since the 1990s, especially following the enormous increase in the use of wireless mobile telephony throughout the world. This is because mobile phones use electromagnetic waves in the microwave range. These concerns have induced a large body of research (both epidemiological and experimental, in non-human animals as well as in humans). Concerns about effects on health have also been raised regarding other digital wireless systems, such as data communication networks.

Although previous studies have shown mixed and often conflicting results, these studies have been criticized for having a low statistical power. The current study included 120 subjects to improve the statistical power of the analyses; 58 males and 62 females from 18 to 70 years. Mind you, such a spread in age could actually be a confounding variable, and an age effect should have been included in the analysis. To that, the current study does not seem to have controlled for age and gender effects on the age sample.

The researchers gave the subjects a number of different cognitive tasks tapping into cognitive functions such as reaction time, encoding, verbal comprehension, and working memory. Radiofrequency radiation was induced through a regular Nokia mobile phone placed on a helmet that subjects wore during cognitive testing. The study was a double-blinded setup, so that neither researchers nor the subjects knew if the cellular phone was transmitting (or emitting radiofrequency radiation). Measures were taken to make sure that neither sound or heating would lead subjects to detect when the phone was transmitting. Subjects performed the tests (different versions of the test each time) during radiofrequency stimulation (both sham and real stimulation).
What was found was that the performance during radiofrequency exposure, compared to sham condition, changed theperformance on several tests. While the performance on reaction time decreased during exposure, performance on the Trail Making test B, which loads working memory, was increased during exposure. As the researchers write:

The results of this study provide statistical evidence of a cognitive difference in performance between the real and sham field [mobile phone] exposure conditions. The negative effects of [radiofrequency] exposure on [reaction time, RT] performance indicate that the more basic functions were adversely affected by exposure. In contrast, the improved RT for the working memory task suggests that [radiofrequency] exposure has a positive effect on tasks requiring higher level cortical functioning, such as working memory.

The results are also very interesting because several reports now support the view that using a cellular phone while driving leads to a reaction time comparable to that of having several alcoholic drinks. Through this study it seems that it’s not only the talking in the phone that pulls your reaction time down; it’s also the mere radiation itself.

But are the conclusions warranted? For one thing: the cognitive measures being made are rather crude. The reactions time measures should be less problematic, but as for concluding that working memory increases due to a Trail Making B test score only is really invalid. The Trail B is indeed a measure of how people can switch from one serial counting mode to another (numbers or alphabet). Working memory is really much more than keeping track of only one number or letter back. What should be applied is a so-called parametric n-back task (PDF). In addition, a better test battery should be applied. Although the current focus has been on reaction time, it now seems likely that effects on higher-order cognitive functions may take place, too. However, in order to make firm conclusions of such, we need better cognitive test batteries.

What, then, happens to our cognitive brains after prolonged exposure to radiofrequency waves? Here, we can only speculate, or as the authors point out:

The implications of this study can only be directed towards the effects of short-term exposure of [mobile phone radiofrequency radiation] on cognition. Further longitudinal research is required to determine the effects that long-term use of [mobile phones] (years) may have on health and cognition.

It’s still early days for studies on mobile phones, radiation and brain funcitoning. Many studies have used a less than optimal sample size and problematic experimental designs. Nevertheless these results seem to point out that just being exposed to radiofrequency radiation from a cellular phone induce changes in the brain’s workings. And now I start wondering whether my subjects in the MR scanner also change during scanning…

-Thomas

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