THE EFFECT OF A 50 HZ MAGNETIC-FIELD ON COGNITIVE FUNCTION IN HUMANS

Objectives: To examine whether the power frequency magnetic field of 0 .6 mT applied to humans has an effect on cognitive function as has bee n suggested by animal studies. These fields are less than the suggeste d intervention level in the UK of 1.6 mT and are similar to those foun d close to some domestic appliances. Method and materials: A randomize d three-way cross-over design using a battery of computerized cognitiv e function tests were used in the presence or absence of a 50 Hz or st atic magnetic field. Sixteen healthy volunteers undertook two training and three test sessions with a 50 Hz or static 0.6 mT magnetic field from a set of coils centred on the head. Results: In response to the 5 0 Hz field, disruptions of accuracy were seen from an attentional task (the ability to correctly recognize words shown 20 min previously and the ability to maintain a string of digits in working memory). There was no similar response to comparable levels of static magnetic field. Conclusions: These tests indicated at least temporary deterioration i n attention. and working and secondary memory performance while a 50 H z field is applied. There were no adverse effects on speed from any of the tasks. It was not possible in this study to be sure if these effe cts were persistent.