title: Simultaneous exposure to MRI-related static and low-frequency movement-induced time-varying magnetic fields affects neurocognitive performance: A double-blind randomized crossover study.
abstract: OBJECTIVE
  This experimental study aims to separate neurocognitive effects resulting from exposure to static magnetic stray fields (SMF) alone and the combination of SMF and low-frequency movement-induced time-varying magnetic fields (TVMF) using a 7 Tesla (T) MRI scanner in stand-by mode.
  
  
  METHODS
  In a double-blind randomized crossover experiment, 36 healthy volunteers underwent four sessions, two exposed conditions, and two corresponding sham conditions. The exposure conditions were in front of the scanner bore and consisted of 1.0 T SMF with or without 2.4 T/s TVMF, induced by standardized head movements before each of the five neurocognitive tasks. These specific tasks were selected because previous experiments showed negative effects of SMF + TVMF exposure on test performance.
  
  
  RESULTS
  Exposure to SMF in combination with TVMF decreased verbal memory performance significantly and changed visual acuity. Similarly, attention and concentration were negatively affected with borderline significance. Exposure to SMF only did not have significant effects on the performance on any of the tasks.
  
  
  CONCLUSIONS
  Neurocognitive effects were only observed when simultaneously exposed to SMF and TVMF from a 7 T MRI scanner. Therefore, exposure to TVMF seems essential in eliciting the neurocognitive effects in our present study and, presumably, previous experiments.
authors.affiliation: Institute for Risk Assessment Sciences, Division of Environmental Epidemiology, Utrecht University, Utrecht, The Netherlands.
authors.forename: Lotte E
authors.initials: LE
authors.lastname: van Nierop
authors.affiliation: Institute for Risk Assessment Sciences, Division of Environmental Epidemiology, Utrecht University, Utrecht, The Netherlands.
authors.forename: Pauline
authors.initials: P
authors.lastname: Slottje
authors.affiliation: Helmholz Institute, Utrecht University, Utrecht, The Netherlands.
authors.forename: Martine
authors.initials: M
authors.lastname: van Zandvoort
authors.affiliation: Institute for Risk Assessment Sciences, Division of Environmental Epidemiology, Utrecht University, Utrecht, The Netherlands.
authors.forename: Hans
authors.initials: H
authors.lastname: Kromhout
mesh_terms: D000293:Adolescent; D003071:Cognition / Q000528:radiation effects*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D060526:Magnetic Fields / Q000009:adverse effects*; D008279:Magnetic Resonance Imaging / Q000009:adverse effects*; D008297:Male; D009483:Neuropsychological Tests; D000069079:Radiation Exposure / Q000009:adverse effects; D011897:Random Allocation; D013647:Task Performance and Analysis; D055815:Young Adult
keywords: cognition; exposure; low frequency movement induced time-varying magnetic fields (TVMF); magnetic resonance imaging (MRI); static magnetic fields (SMF); static magnetic stray fields