An anti-seizure drug commonly used to treat epilepsy could put the brakes on Alzheimer's, according to a new U.S. study.

Scientists from John Hopkins University in Baltimore said Wednesday that the drug levetiracetam can improve the memory of patients with mild cognitive impairment (MCI), a form of dementia that can lead to Alzheimer's.

It also reduced excess activity in the patients' hippocampus, the part of the brain that is essential for memory. People found to have overactivity in this part of the brain are more likely to develop Alzheimer's in the following four to six years.

"This excess activity might be like having your foot on the accelerator if you are on the path to Alzheimer's," according to Michela Gallagher, professor of psychological and brain sciences at the university.

Her team analyzed 34 volunteers, some of who were healthy and some who had MCI, and tested their brain activity after two phases of treatment.

Gallagher said the effect of the drug was "like taking your foot off the accelerator or tapping the brakes."

The drug reduced the overactivity in the brain of those with MCI to the normal level experienced by the healthy test participants.

The study was presented at the International Conference on Alzheimer's Disease in Paris.