Influence of static magnetic fields on cognitive performance

Volunteer at the entrance of the scanner Source: DKFZ Heidelberg

The research project "Effects of exposure to strong static magnetic fields on the cognitive performance of volunteers" ("Auswirkung der Exposition mit starken statischen Magnetfeldern auf die kognitive Leistungsfähigkeit von Probanden") was carried out between 2008 and 2011 at the German Cancer Research Center Heidelberg and at the Central Institute for Mental Health Mannheim, Germany. This project addressed the question of whether, and if so, to what extent, exposure to static magnetic fields or moving within the gradients of static magnetic fields influence the well-being and cognitive performance of patients and particularly of medical staff.

Absolute performance of the medical staff must be warranted in order to exclude any hazard to patients especially during surgical interventions carried out using open MRI devices.

Method

Ten different tests on attention, reaction time, memory, eye-hand-coordination, visual contrast sensitivity and visual resolution, well-being and stress were carried out within the static magnetic field of three MRI scanners with different magnetic flux densities (1.5, 3 and 7 Tesla) and a field-free space as a control under equal environmental conditions. To quantify the magnetic field strength, a measuring instrument was developed enabling simultaneous measurement of the local magnetic flux density and its time variation for individual volunteers.

Results

A total of 41 test persons (21 male, 20 female) aged from 18 to 34 were examined at all flux denisities, both within the centre of the magnet bore and when moving through a gradient of the magnetic field at the entrance of the scanner. The examination was single-blinded, i.e. test persons were not informed as to the flux density applied for testing.

Exposure to the different static magnetic fields of up to seven Tesla had no significant effects on the results of the individual cognition tests. As to well-being, the occurrence of dizziness, nystagmus (eye twitching), light flashes, and ringing in the head was found to be significantly correlated with increase in flux density. Dizziness was more pronounced at seven Tesla than under all other conditions but did not occur any more in eighty per cent of the test persons after a short adaptation period of several minutes.

Measurement of the stress hormones before, during, and after the examination based on blood and saliva samples revealed no significant effects of flux density.

The test persons’ estimates collected by means of a questionnaire as to the flux density they had been exposed to at a given day of testing revealed that blinding was successful. The test persons’ estimates of flux density were not better than random estimates.

Summary

The indications from scientific literature as to the occurrence of dizziness were able to be confirmed, primarily within a magnetic field strength of seven Tesla and during movements within the gradient of a static magnetic field The perception of dizziness had no influence on the cognitive performance of the test persons. Most of the test persons were able to rapidly adapt to the fields and subsequently had no complaints any more.

More information

• Auswirkung der Exposition mit starken statischen Magnetfeldern auf die kognitive Leistungsfähigkeit von Probanden - Vorhaben 3608S03009 (Final Report in German with abstract in English)
• Heinrich A, Szostek A, Nees F, Meyer P, Semmler W, Flor H (2011) Effects of static magnetic fields on cognition, vital signs, and sensory perception: a meta-analysis. J Magn Reson Imaging. 34(4): 758 - 763
• Heinrich A, Szostek A, Meyer P, Nees F, Rauschenberg J, Gröbner J, Gilles M, Paslakis G, Deuschle M, Semmler W, Flor H (2013) Cognition and sensation in very high static magnetic fields: a randomized case-crossover study with different field strengths. Radiology. 266(1): 236 - 245
• Gilles M, Paslakis G, Heinrich A, Szostek A, Meyer P, Nees F, Rauschenberg J, Gröbner J, Krumm B, Semmler W, Flor H, Meyer-Lindenberg A, Deuschle M. (2013) A cross-over study of effects on the hypothalamus-pituitary-adrenal-(HPA-) axis and the sympathoadrenergic system in magnetic field strength exposure from 0 to 7 Tesla. Stress 16(2): 172 – 180
• Groebner J, Umathum R, Bock M, Krafft AJ, Semmler W, Rauschenberg J (2011) MR safety: simultaneous B0, dΦ/dt, and dB/dt measurements on MR-workers up to 7 T. MAGMA. 24(6): 315 - 322

• Heinrich A, Szostek A, Meyer P, Reinhard I, Gilles M, Paslakis G, Rauschenberg J, Gröbner J, Semmler W, Deuschle M, Meyer-Lindenberg A, Flor H, Nees F (2014) Women are more strongly affected by dizziness in static magnetic fields of magnetic resonance imaging scanners. Neuroreport, 25(14):1081-1084