DOI: 10.6084/m9.figshare.29819208.v1
title: Low frequency magnetic field exposure and neurodegenerative disease: systematic review of animal studies

description: Epidemiological studies have found an association between occupational exposure to low frequency magnetic fields and the occurrence of motor neuron disease and Alzheimer’s disease. No association has been found for Parkinson’s disease and the evidence for multiple sclerosis is insufficient. Animal models studying the effects of low frequency magnetic fields on neurodegenerative disease induction or progression could provide more evidence on causation and the underlying mechanisms. A systematic search and review was conducted of peer-reviewed research articles involving animal experiments on the effects of low frequency magnetic field exposure on behavioural and neuroanatomical outcomes relevant for neurodegenerative diseases in humans. Firstly, experimental studies in <i>naive animals</i> do not support a causal relationship between exposure to low frequency magnetic fields and the induction of neuropathology relevant for Alzheimer’s disease, but the number of studies relevant for motor neuron disease, multiple sclerosis and Parkinson’s disease is too limited to draw conclusions. Secondly, experimental studies in <i>existing animal models for neurodegenerative disease</i> support a therapeutic (beneficial) effect of low frequency magnetic field treatment on behavioural and neuroanatomical abnormalities relevant for dementia (including Alzheimer’s disease), multiple sclerosis and Parkinson’s disease and no effect on disease progression in models relevant for motor neuron disease. Magnetic fields with low frequencies (between 1 Hz and 100,000 Hz) are produced by electricity lines and electric devices that use alternating current. Exposure to low frequency magnetic fields in certain workplaces, such as power plants or welding, can be higher than in the home. Workers are protected against known, immediate health effects of magnetic fields by legal limits. Scientists have also investigated if longer exposure to weaker magnetic fields is linked to diseases in workers. Their research has found some evidence for an increase in certain neurological diseases, in particular Alzheimer’s and motor neuron disease or amyotrophic lateral sclerosis. To find out if the magnetic fields are the real cause for these diseases, experiments have also been done in laboratory animals. This paper summarises the findings in scientific papers published about these experiments. Exposure of healthy rats or mice to low frequency magnetic fields does not cause signs of disease similar to those in Alzheimer’s. Too few animal studies have been done about signs of motor neuron disease, Parkinson’s disease or multiple sclerosis to draw conclusions. Rats or mice with an existing neurological disease, for example because of a genetic defect, have also been treated with low frequency magnetic fields. In these experiments, the magnetic field generally had a beneficial effect. It lessened the disease symptoms in animals with a condition similar to Alzheimer’s, Parkinson’s disease or multiple sclerosis. It did not have a clear effect in animals with a condition similar to motor neuron disease.