Use of mobile phones and changes in cognitive function in adolescents

Background Several studies have investigated the impact of mobile
phone exposure on cognitive function in adults. However, children
and adolescents are of special interest due to their developing
nervous systems. Methods Data were derived from the Australian
Mobile Radiofrequency Phone Exposed Users' Study (MoRPhEUS) which
comprised a baseline examination of year 7 students during
2005/2006 and a 1-year follow-up. Sociodemographic and exposure
data were collected with a questionnaire. Cognitive functions were
assessed with a computerised test battery and the Stroop Color-Word
test. Results 236 students participated in both examinations. The
proportion of mobile phone owners and the number of voice calls and
short message services (SMS) per week increased from baseline to
follow-up. Participants with more voice calls and SMS at baseline
showed less reductions in response times over the 1-year period in
various computerised tasks. Furthermore, those with increased voice
calls and SMS exposure over the 1-year period showed changes in
response time in a simple reaction and a working memory task. No
associations were seen between mobile phone exposure and the Stroop
test. Conclusions We have observed that some changes in cognitive
function, particularly in response time rather than accuracy,
occurred with a latency period of 1 year and that some changes were
associated with increased exposure. However, the increased exposure
was mainly applied to those who had fewer voice calls and SMS at
baseline, suggesting that these changes over time may relate to
statistical regression to the mean, and not be the effect of mobile
phone exposure.