Noninvasive stimulation of key brain regions could help people reverse the common age-related decline in working memory—our ability to remember names, numbers, and other tidbits of information—according to a study published in Nature Neuroscience today (April 8). The approach, known as transcranial alternating current stimulation (tACS), allowed researchers to improve the synchronization of activity between the frontal cortex and the temporal cortex, which appears to be important for working memory.
“This study suggests that age-related impairment in one particular form of short-term memory largely reflects a failure of synchronization,” Michael Kahana, a brain scientist at the University of Pennsylvania who was not involved in the research, tells The New York Times. If the approach is validated in additional studies and proves useful for improving other types of memory, he adds, “it could be a game changer for the treatment of age-related memory decline and possibly even dementia.”
The study, led by neuroscientists Robert Reinhart and John Nguyen of Boston University, used electroencephalography (EEG) to monitor and noninvasively stimulate the brains of two groups of participants: 42 people aged 20 to 29 years and 42 people aged 60 to 76. Comparing the two groups’ performances on working-memory tasks, the researchers found that the older individuals were slower and less accurate at recalling items they’d seen or identifying subtle differences between two nearly identical images. The older group also had a lower synchronization of brain activity between the frontal and temporal cortices.
Stimulating these two brain regions with tACS for 25 minutes improved that synchronization, as well as the subjects’ performance on the memory test, such that their scores were comparable to those of the younger group—an effect that lasted for 50 minutes or more following the stimulation. “By using this type of stimulation (we found) we can reconnect or resynchronize those circuits,” Reinhart told reporters in a telephone briefing, according to Reuters. “We can bring back the superior function you had when you were much younger,” he adds, according to the Times.
The study’s younger participants did not receive such impressive benefits from the stimulation, the researchers found, suggesting that while it may help reverse memory declines, this application of tACS is unlikely to enhance a still-sharp memory. Of course, even for older individuals, much more research is needed before tACS becomes a validated treatment for memory issues of any sort, whether that be age-related declines or symptoms of dementia.
Still, it’s a step in the right direction for what has been a somewhat controversial approach. “I’m really excited by this paper,” Marom Bikson, a biomedical engineer at the City College of New York who did not participate in the research, tells NPR. “It advances the needle towards establishing a rigorous scientific base for this kind of brain stimulation technique.”