ABSTRACT
BACKGROUND AND OBJECTIVE: Numerous studies have investigated the potential effects of electromagnetic fields (EMFs) emitted by GSM mobile phones ( approximately 900 MHz to approximately 1800 MHz) on cognitive functioning, but results have been equivocal. In order to try and clarify this issue, the current study carried out a meta-analysis on 19 experimental studies. DESIGN: Meta-analysis. METHODS: Nineteen studies were taken into consideration. Ten of them were included in the meta-analysis as they fulfilled several minimum requirements; for example, single-blind or double-blind experimental study design and documentation of means and standard deviation of the dependent variables. The meta-analysis compared exposed with non-exposed subjects assuming that there is a common population effect so that one single effect size could be calculated. When homogeneity for single effect sizes was not given, an own population effect for each study and a distribution of population effects was assumed. RESULTS: Attention measured by the subtraction task seems to be affected in regard to decreased reaction time. Working memory measured by the N-back test seems to be affected too: under condition 0-back target response time is lower under exposure, while under condition 2-back target response time increases. The number of errors under condition 2-back non-targets appears to be higher under exposure. CONCLUSION: Results of the meta-analysis suggest that EMFs may have a small impact on human attention and working memory.
Subject(s)
Cell Phone , Electromagnetic Fields/adverse effects , Mental Processes/radiation effects , Reaction Time/radiation effects , Adult , Aged , Aged, 80 and over , Analysis of Variance , Dose-Response Relationship, Radiation , Female , Humans , Male , Middle Aged , Neuropsychological Tests , Randomized Controlled Trials as TopicABSTRACT
OBJECTIVE: Orthostatic intolerance (OI) is a syndrome that is characterised by headache, concentration difficulties, palpitation of the heart, dizziness associated with postural tachycardia and plasma norepinephrine concentrations that are disproportionately high when the sufferer is in the upright posture. In contrast to other forms of orthostatic dysregulation - orthostatic hypotension (OH) and postural orthostatic tachycardia syndrome (POTS) - OI, hitherto, could be diagnosed only by a tilt table examination, with high expenditure. In this paper we examine the reliability and validity of a questionnaire as a screening instrument for OI. METHODS: We studied 138 young men (mean age 21.6 years) who were undergoing military service. After a medical check and filling in the questionnaire, the participants underwent a tilt table test including monitoring of blood pressure, heart rate and plasma catecholamines, in the supine position and during 30 min of standing. The questionnaire consisted of ten items registering presence and frequency of typical OI symptoms. RESULTS: Probands (104) showed normal tilt table test results. OI was diagnosed in 14 probands, OH in 6 and POTS in 14. The OI participants scored significantly higher in the questionnaire than the healthy subjects did: the mean score of the OI group was 22.6, the healthy participants had a mean score of 3.9. Participants with POTS had a mean score of 13.5 and subjects with OH had a mean score of 17.0. Reliability analysis showed a Cronbach's alpha of 0.888. Validity analysis showed that 93.5% of the probands with any kind of orthostatic dysregulation can be detected. CONCLUSIONS: We were able to establish a short questionnaire as a reliable and valid screening instrument for OI. Usage of this questionnaire can simplify enormously the diagnostic management of patients with suspected OI.
