Magnetic stimulation can be used for conditions such as depression

Scientists in New York promoted the growth of new neurons in the brains of mice using a magnetic stimulus in the region associated with memory.

Presenting the results at the American Academy for Neuroscience conference, the researchers said the results may lead to treatments for Alzheimer's.

However, if proven the technique is more likely to be a way of slowing progression of the disease than a cure.

Experts said the work was encouraging but would need to be replicated in humans.

Trans cranial magnetic stimulation (TMS) has been used to treat certain disorders, including depression and schizophrenia and to rehabilitate people after stroke.

It used a magnetic coil to introduce electrical fields in the brain, which activates or deactivates groups of neurons.

The work is particularly encouraging for the use of brain stimulation in chronic disease such as stroke and dementia

Professor Vincent Walsh

To look at the effect of TMS on growth of neurons, Dr Fortunato Battaglia and Dr Hoau-Yan Wang at City University in New York, gave mice the therapy for five days and then examined their brains, New Scientist magazine reported.

They found large increases in the proliferation of stem cells - immature cells that go on to develop into nerves and other kinds of tissue - in a part of the brain called the dentate gyrus hippocampus.

These cells divide throughout life and are believed to play a crucial role in memory and mood regulation.

In particular they found one receptor in the cells was activated.

A subsequent study which is due to be published shortly showed that the activity of this receptor declines in mice and humans with Alzheimer's disease.

Brain recovery

Taking the two studies together, Dr Battaglia said there were important implications for neurorehabilitation.

"When you have a stroke there is an area that is damaged and there are several ways your brain can recover.

"One is that the area which is not damaged will have to work more and it's that we can promote with brain stimulation."

He added that the hippocampus is much deeper in the brains of humans so it would be important to make sure the technique could produce the same effect as in mice.

"But it might improve symptoms or delay progression of things like Alzheimer's disease," he added.

Professor Vincent Walsh from the Institute of Cognitive Neuroscience at University College London said the findings were a good first step.

"There are lots of examples of TMS enhancing function in some way but we have never been able to explain the mechanics of how it might work.

"The work is particularly encouraging for the use of brain stimulation in chronic disease such as stroke and dementia.

"The challenge now is to find ways of combining stimulation with drug therapies."

Professor Clive Ballard, director of research at the Alzheimer's Society said: "This is a potentially interesting piece of work, but is a preliminary study in mice.

"Further research is now needed before we can find out if TMS is a useful treatment approach for Alzheimer's disease in humans."