Electromagnetic fields from cellular and cordless phone excite the user's brain cortex adjacent to it, which may have implications for patients with some neurological diseases, according to Italian research released on Monday.

More than 500 million people in the world use mobile phones that emit electromagnetic fields (EMFs), known as Global System for Mobile communications. Many studies have looked at the effects of EMFs on the human body.

Italian researchers, led by Dr. Paolo Rossini of Fatebenefratelli hospital in Milan had 15 young male volunteers exposed to EMF signals from a GSM 900 cell phone for 45 minutes and checked the excitability of cells in their brain cortex before, during and after the phone use.

Results showed that in 12 of the 15 volunteers, an excitability change occurred in the cells of the motor cortex adjacent to the phone, and these cells returned to normal condition within an hour after the exposure. The researchers reported their findings in the latest issue of Annals of Neurology published on Monday.

The cortex is the outside layer of the brain and the motor cortex is an area of the brain where movement is controlled.

The researchers said it would be premature to conclude that cell phone use is bad for the brain in any way, but it may affect people with neurological conditions such as epilepsy, which is linked with brain cell excitability.

They concluded that further studies were needed to clearly investigate the links between brain-disease conditions possible and to provide safe rules for the increasingly widespread use of cell phones.

Previous medical studies had provided controversial results on the effects of cell phone use. Some researchers found that longtime cell phone use may raise the risk of brain tumors, but other studies found no evidence that emissions from cell phones were harmful.