Effect of a 915-MHz simulated mobile phone signal on cognitive function in man.

Purpose : To examine whether a simulated mobile telephone transmission at 915MHz has an eff ect on cognitive function in man. Materials and methods : Thirty-six subjects in two groups were each given two training sessions and then three test sessions in a randomized three-way cross-over design. About 1W mean power at 915MHz from a quarter-wave antenna mounted on a physical copy of an analogue phone, as a sine wave, or modulated at 217Hz with 12.5% duty cycle, or no power, was applied to the left squamous temple region of the subjects while they undertook a series of cognitive function tests lasting 25-30min. The second group was investigated for sleep, consumption of alcohol and beverages, and any other substances that might aff ect performance. Results : In both groups, the only test aff ected was the choice reaction time and this showed as an increase in speed (a decrease in reaction time). There were no changes in word, number or picture recall, or in spatial memory. While an eff ect of visitorder was evident suggesting a learning eff ect of repeat tests, the design of the study allowed for this. Additionally, there was no systematic error introduced as a result of consumption of substances or sleep time. Conclusions : There was evidence of an increase in responsiveness, strongly in the analogue and less in the digital simulation, in choice reaction time. This could be associated with an eff ect on the angular gyrus that acts as an interface between the visual and speech centres and which lies directly under and on the same side as the antenna. Such an eff ect could be consistent with mild localized heating, or possibly a non-thermal response, which is nevertheless power-dependent. [ABSTRACT FROM AUTHOR]