Epidemiological study (observational study)

Use of mobile phones and changes in cognitive function in adolescents epidem.

By: Thomas S, Benke G, Dimitriadis C, Inyang I, Sim MR, Wolfe R, Croft RJ, Abramson MJ

Published in: Occup Environ Med 2010; 67 (12): 861-866

Aim of study (acc. to author)

The MoRPhEUS study (Australian Mobile Radiofrequency Phone Exposed Users' Study) was conducted to examine possible associations between exposure to mobile phones and cognitive function in Australian adolescents. The results of the baseline examinations are published in Abramson et al. (2008).
Aim of the present study was to investigate whether an effect in cognitive outcome occured after a 1-year period and/or whether an increase in exposure over the period was followed by changes in cognitive outcome.

Further details

Cognitive function was assessed by the computerized psychometric CogHealth test and the Stroop test.

Endpoint/type of risk estimation

cognitive function (signal detection, working memory, learning, Stroop test)

Type of risk estimation:

prevalence

Exposure

- mobile communications
- digital mobile phone
- personal

Assessment

questionnaire: average number of calls made and received per week, number of text messages (SMS) made and received per week

Population

Group:
- children
Age: 12–15 years
Characteristics: students of secondary schools who took part in the baseline assessment
Observation period: 2006 - 2007
Study location: Australia (Melbourne)
Data source: Australian Mobile Radiofrequency Phone Exposed Users' Study (MoRPhEUS)
Exclusion criteria: students with known cognitive disorder and those receiving medication known to impair or alter cognitive function

Study size

Type	Value
Eligible	317
Participants	236

Statistical analysis method:

multiple linear regression analysis

(adjustment:

age
sex
socioeconomic status
ethnicity (languages other than English spoken at home), growth (difference in height between 1st and 2nd examination) D: Herkunft (andere Sprachen als Englisch zu Hause gesprochen), Wachstum (Unterschied in Körpergröß

)

Results (acc. to author)

The proportion of mobile phone owners, the total number of voice calls and SMS per week increased from baseline to follow-up. 75% of the adolescents owned a mobile phone at the baseline and 86 % at follow-up. At baseline, students reported a median of 8 voice calls and 8 SMS per week, at follow-up a median of 10 voice calls and 10 SMS per week. The increase in exposure over the study period was mainly observed among those with lower numbers of calls at baseline.
Associations between the use of mobile phones and changes in some of the cognitive outcomes were observed, especially changes in response times rather than changes in accuracy. Participants with more voice calls and SMS at baseline, but no increase in exposure at follow-up, showed lesser reductions in response times over the 1-year period in some of the CogHealth tasks. No associations were seen between mobile phone use and the Stroop Color-Word test. Furthermore, differences in the number of text messages were not related to changes in any of the CogHealth or Stroop tasks.
The authors concluded that the observed changes in cognitive function over time may relate to statistical regression toward the mean, and not be the effect of mobile phone exposure.

Study funded by

National Health and Medical Research Council (NHMRC), Australia

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