Study says memory can be boosted by electric shocks. We take it for granted, but practically all of our daily activities depend on having a memory. Talking, reading, understanding, socializing—these all depend on having learned and stored information about our environments.
It’s our memory that allows us to retrieve events from moments ago or from the distant past, enabling us to form habits and learn new skills. If we were unable to access past experiences or information, we’d also be unable to recognize our friends or family, find our way home, understand language, or even knot our neckties. Life would be a series of disconnected experiences—each one new and unfamiliar. Without any sort of memory, we’d quickly perish.
But that’s exactly what happens to six million Americans and 30 million people worldwide who get struck by Alzheimer’s disease. The sixth leading cause of death in the U.S. and the fifth leading cause of death for people 65 and older, it’s a form of dementia that affects memory, thinking and behavior.
“Losing our ability to remember recent events and to form new memories is one of the most dreaded afflictions of the human condition,” says Dr. Itzhak Fried, professor of neurosurgery at the David Geffen School of Medicine at University of California, Los Angeles.
Dr. Fried led the researchers who found, in a new study, that applying mild electric shocks to a person’s brain just before they learned a new task appeared to strengthen memory. The study, done on a handful of patients with epilepsy, was published in the Feb. 9 New England Journal of Medicine.
“Our preliminary results provide evidence supporting a possible mechanism for enhancing memory, particularly as people age or suffer from early dementia,” says Dr. Fried in a news release. “At the same time, we studied a small sample of patients, so our results should be interpreted with caution.”
Deep-brain stimulation — or giving the brain an electric jolt — is already used to treat ailments like Parkinson’s disease and chronic pain.
Pacemaker-like devices known as deep brain stimulators have for some time been used to calm muscle tremors in patients with Parkinson’s and a movement disorder known as dystonia. They’re also being tested for a host of other conditions such as drug- and therapy-resistant depression.
Implanted under the skin in the chest, the devices have wires leading up to the neck, which are connected to tiny electrodes implanted deep in the brain. The devices, used to produce tiny electrical impulses, have been approved by the Food and Drug Administration to treat Parkinson’s, dystonia, chronic pain and severe depression.
But unlike the electrical stimulation used to treat Parkinson’s and similar conditions, where the brain is stimulated continuously or repeatedly with the implanted pacemaker-like device, in the new study, memory was improved by single burst of current administered to a specific location that’s critical to memory at the moment that memories was being formed, says Dr. Fried.
What the researchers did
The UCLA researchers worked with seven epilepsy patients who already had electrodes implanted in their brains to monitor the origin of their seizures.
Researchers recorded the brain activity of the seven patients as they completed a computer game where they pretended to be taxi drivers who needed to drop passengers off at stores on different “blocks” in a “city.”
Researchers stimulated the brains of participants at the moments when they were learning half of the store locations — but didn’t apply the mild shock when participants were learning the other half of store locations. Participants were then tested for how well they remembered the stores’ location.
Regardless of how good their memory was, all patients saw improvement in their memory after stimulation in a particular brain region known as the entorhinal area. When researchers stimulated the brain just millimeters from this area, memory wasn’t improved.
The scientists stimulated a brain site called the entorhinal cortex, considered the gateway to the hippocampus that helps form and store memories.
“The entorhinal cortex is the golden gate to the brain’s memory mainframe,” says Dr. Fried. “Every visual and sensory experience that we eventually commit to memory funnels through that doorway to the hippocampus. Our brain cells must send signals through this hub in order to form memories that we can later consciously recall.”
When Dr. Fried’s team members stimulated the nerve fibers in their entorhinal cortex, study participants recognized landmarks and navigated the routes more quickly. “They even learned to take shortcuts, reflecting improved spatial memory,” Dr. Fried tells CBS News.
Stimulation was used only during the learning phase—suggesting that stimulation was only needed when people are trying to learn important information, Dr. Fried surmises. Patients don’t need continuous stimulation to boost their memory.
Stephen Salloway, an Alzheimer’s researcher and neurology professor at Brown University says the findings “break new ground” for the field of Alzheimer’s. “It doesn’t provide a definitive answer; it opens new doors to exploratory treatments for Alzheimer’s,” Dr. Salloway, who wasn’t involved in the current study, tells the Wall Street Journal.
Another neuroscientist who wasn’t involved in the study, Dr. Suzanne Haber, who works at New York’s University of Rochester Medical Center says she is “very excited about the finding.”
But in an interview with Reuters, Dr. Harber cautions that the treatment is “very invasive, very expensive and unproven” in Alzheimer’s patients.
The Obama administration said on Feb. 8 that it plans to spend an additional US$156 million over the next two years to help find an effective treatment for Alzheimer’s, Reuters reports.
In 2010, another team of researchers tried deep brain stimulation in Alzheimer’s patients. In a study published in the Annals of Neurology, scientists tested deep brain stimulation in six patients over the course of a year. They saw signs the treatment might have an effect on memory and found the treatment to be relatively safe.
In an editorial on the current study, Dr. Sandra Black, a brain researcher at the University of Toronto writes that if tests were developed to identify Alzheimer’s early in its progression through imaging or genomics, the new findings could help improve treatments for disease.
“Although the current evidence is preliminary, is based on small samples and requires replication, the potential application of deep-brain stimulation in amnestic disorders is enticing,” Dr. Black writes.
Science writer Mo Costandi urges caution: “It was a small study so the findings should be interpreted with caution, but they could have clinical applications if confirmed,” he writes in his blog, Neurophilosophy, syndicated by Guardian Blogs.
“Previous studies have shown that direct stimulation of the human hippocampus has detrimental effects on memory,” he warns, “but these new results identify the entorhinal cortex, and possibly the perforant path, as potential targets for memory enhancement,” he adds.
Could the treatment be used by people without memory impairment just to improve their memory?
Indeed, scientists have enhanced learning with electrical stimulation before as a side-effect of stimulation for another purpose. This happened many times in rodents and at least once in a human.
In the 1980s, scientists directly stimulated a brain region in humans called the hippocampus, which is critical in memory formation, but the current interfered with new memories.
The new findings have already piqued the interest of people with normal memory function who seek a little intellectual edge, says Dr. Andres Lozano, a neurosurgeon at the University of Toronto. But he tells the Los Angeles Times, “These are major ethical issues society will have to grapple with when the time comes. This opens up a Pandora’s box.”