Brain stimulation to treat Alzheimer's?

In a very small group of patients, sending electrical impulses to a memory-center in the brain - via tiny implanted electrodes - may have improved their memory.

The new study provides hope, albeit a small glimmer, that deep brain stimulation could one day help patients diagnosed with early Alzheimer's disease .

"Can this be used for cognitive or memory enhancement with patients with serious memory impairment?" said Dr. Itzhak Fried, a study co-author and professor of neurosurgery at the David Geffen School of Medicine at UCLA. "This is a question not answered by this study, but this study points to a possible direction for the future."

In the study, published in the New England Journal of Medicine , seven epilepsy patients with electrodes already embedded in their brains (they were being monitored for spontaneous seizures) were asked to play a video game to test their memory. During the game, the patients navigated a virtual world, delivering people in a taxi to various shops.

Patients who had a memory center in the brain - called the entorhinal cortex - electrically stimulated while navigating the virtual world were able to reach the shops quicker, and in some cases found shortcuts, compared with those who were not stimulated.

The entorhinal cortex is a sort of processing center in the brain, funneling everyday information - for instance, who you are meeting for lunch tomorrow - to the hippocampus , where lasting memories are formed. The suggestion made by this study is that stimulating the entorhinal cortex while performing a task may help to cement memories.

"We're stimulating a critical node of a very complex network, but how exactly it works we do not know," said Fried.

And it is not yet known whether this stimulation will work with a wider swath of memory-impaired patients.

Deep brain stimulation is now used to treat Parkinson's disease ; small studies have also suggested it may be useful for treating obsessive-compulsive disorder , and major depression. A study  published recently in the Annals of Neurology found that constant stimulation of another memory pathway, called the fornix, may have sparked neuron growth and slowed down cognitive decline in a small group Alzheimer's patients.

But most deep brain stimulation studies are small (besides, implanting electrodes in the brain is invasive and often a last-ditch effort to treat a disease), so this most recent study's authors and outside experts emphasize caution when interpreting results.

"This study gives us more things to think about and more possible ways to intervene," said Dr. Rachelle Doody, an Alzheimer's disease expert unaffiliated with this study, and spokesperson for the American Academy of Neurology . "But right now it's interesting science, not medicine and not a treatment."