Stimulating the brain with an electrical current can improve memory, according to a study that suggests a novel approach to treating Alzheimer’s disease and dementia.
Researchers at the University of California, Los Angeles studied seven volunteers with epilepsy who already had electrodes implanted in their brains to detect seizures, and found that memory improved when the electrodes were turned on during tasks. The study, published Wednesday in the New England Journal of Medicine, was designed to test a theory shown in animal studies that stimulation deep in the brain improves recall.
“What we found here was a particular golden gate, a small area in the entorhinal cortex, where stimulation has a striking effect on memory,” said lead researcher Itzhak Fried, a professor of neurosurgery at UCLA, in a telephone interview. “This is an area of the brain which is critical in transformation of experience into lasting memories.”
The findings have implications for patients with Alzheimer’s disease and dementia. The volunteers had varying memory strength and all improved when the electrical stimulation was turned on, Fried said. The tasks depended on spatial memory, a key component of everyday living such as finding your car in a parking lot and remembering where you stashed the keys, he said.
Study volunteers played a video game in which they acted as a taxicab driver shuttling passengers across a virtual city. The electrodes received electrical stimulation while patients learned to get to three stores, and were turned off for another three. In a subsequent test, volunteers were able to find short cuts and get to the stores they visited while the stimulation was on more quickly. That showed improved spatial memory, said lead researcher Fried.
The study also shows it’s possible to reach circuits in the brain involved with processing memory and that electrical stimulation can enhance their function, said Andres Lozano, chair of neurosurgery at the University of Toronto. The approach may have treatment implications for patients with memory disturbances, said Lozano, who wasn’t involved in the study.
The location of the electrodes was key, Fried said. Stimulation of the hippocampus, a key component of the brain that converts short-term experience into long-term memory, didn’t help. The hippocampus is one of the first areas where destruction from Alzheimer’s disease occurs. However, the stimulation was beneficial when it occurred at the entorhinal cortex, which leads to the hippocampus.
Tiny electrodes, measuring less than 2 millimeters in size, were placed a little less than two inches into the brain. None of the patients felt the stimulation.
“Alzheimer’s disease is the big target here because it’s such a huge problem with people getting older,” said Matt Stead, a neurologist at the Mayo Clinic in Rochester, Minn., who wasn’t involved in the study. “This is probably one of the most hopeful things I’ve seen regarding Alzheimer’s disease in a long time, because none of the medicines seem to do much.”