Now 'pacemaker' in brain to prevent memory loss in Alzheimer's

The device, which uses deep brain stimulation, has already been used in thousands of people with Parkinson's disease as possible means of boosting memory and reversing cognitive decline.

Instead of focusing on drug treatments, many of which have failed in recent clinical trials, researchers at the Johns Hopkins University School of Medicine are using low-voltage electrical charges delivered directly to the brain.

As part of a preliminary safety study in 2010, the devices were implanted in six Alzheimer's patients in Canada.

The trial showed that patients with mild forms of the disorder showed sustained increases in glucose metabolism - an indicator that brain neurons are working - over a 13-month period.

Most Alzheimer's disease patients show decreases in glucose metabolism over the same period.

The first US patient in the new trial underwent surgery at The Johns Hopkins Hospital in November, and a second patient is scheduled for the same procedure in December.

"Recent failures in Alzheimer's disease trials using drugs such as those designed to reduce the build-up of "plaques" in the brain have sharpened the need for alternative strategies," Paul B Rosenberg, associate professor of psychiatry and behavioural sciences at the Johns Hopkins University School of Medicine, said.

"This is a very different approach, whereby we are trying to enhance the function of the brain mechanically. It's a whole new avenue for potential treatment for a disease becoming all the more common with the ageing of the population," he said in a statement.

Some 40 patients are expected to receive the deep brain stimulation implant over the next year or so at Johns Hopkins and four other institutions in the US.

The surgery involves drilling holes into the skull to implant wires into the fornix on either side of the brain.

The fornix is a brain pathway instrumental in bringing information to the hippocampus, the portion of the brain where learning begins and memories are made, and where the earliest symptoms of Alzheimer's appear to arise.

The wires are attached to a pacemaker-like device, the 'stimulator', which generates tiny electrical impulses into the brain 130 times a second. The patients don't feel the current, said Rosenberg.

For the trial, all of the patients will be implanted with the devices. Half will have their stimulators turned on two weeks after surgery, while the other half will have their stimulators turned on after one year.

"Deep brain stimulation might prove to be a useful mechanism for treating Alzheimer's disease, or it might help us develop less invasive treatments based on the same mechanism," said Rosenberg.