Magnetic stimulation of the brain could improve memory, according to new research that holds promise for treating Alzheimer’s disease and other forms of dementia.

Experiments on mice have suggested that coils generating magnetic fields can strengthen brain circuits in ways that enhance learning and the animals’ ability to remember.

The findings, which were presented recently at a meeting of the American Academy of Neurology in Boston, suggest that the technique, known as transcranial magnetic stimulation (TMS), could open new ways of treating memory decline in people. Further animal experiments are still needed before it can be cleared to start human trials. TMS is a technique that involves placing a magnetic coil on the outside of the skull, generating a magnetic field that can be targeted to affect particular brain regions within.

The precise mechanism by which it works remains unknown, but it has already been used experimentally to treat brain conditions such as depression and schizophrenia, and to rehabilitate people after strokes.

In the new study, reported today in New Scientist magazine, a team at the City University of New York used TMS to stimulate the brains of mice for five days, after which the brains were analysed for evidence of cell growth, and a strengthening of brain circuitry known as long-term potentiation.

The team, led by Fortunato Battaglia, found that the TMS exposure had enhanced long-term potentiation in every region of the brain that was examined. The scientists also found evidence of pronounced stem-cell expansion in the hippocampus, a region that is involved in memory.

“The effect on the stem cells is the most exciting finding,” Dr Battaglia said. TMS might eventually be used to treat age-related memory decline and forms of dementia such as Alzheimer’s, which is associated with a loss of cells in the hippocampus, he added. John Rothwell, of the Institute of Neurology at University College London, said he thought it unlikely that the technique would stimulate the growth of new neurons in the brain, but that it could slow the progress of dementia by strengthening the links between existing cells. “It may be a way of reinforcing connections that are becoming weaker,” he said.

In a separate study published in the journal Neuron, a team led by Hongjun Song, of Johns Hopkins University in Baltimore, has found new evidence that brain cells generated in adulthood are important to learning and memory. While it was once thought that neurons do not form in the brain after childhood, it is now known that fresh growth takes place in adulthood too.

The research suggests that new neurons formed in the hippocampi of adult mice have similar properties to those that grow when the brain and nervous system are developing – giving the mature brain the learning abilities that all brains have while young.

Main attraction

Use of magnets in medicine dates back to classical Greece, when rings of magnetised metal were used to treat arthritis

Paracelsus, a prominent physician in the 15th century, believed that magnetic forces energised the body and promoted self-healing. This concept was further developed and used by Mesmer, who used magnets to treat patients

In the Middle Ages, doctors used magnets to treat gout, arthritis, poisoning, and baldness; to clean wounds and to retrieve arrowheads from the body

They have been sold for conditions, including pain, respiratory problems, high blood pressure, circulatory problems, arthritis, rheumatism, and stress

Source: National Institutes of Health

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