For four consecutive days, 150 senior citizens pulled on a swim-like cap and allowed parts of their brain to be bathed with low-dose electrical pulses. During 20-minute sessions, they were given five lists of 20 words each and asked to recall them.
In some, the oscillations were directed to an area of the brain known to be involved in short-term memory, where a just-learned phone number would be stored. They were tested to see how many recently-mentioned words they remembered.
In others, the pulses were aimed farther forward, in an area known for storing memories longer-term. For them, though they didn’t know it, the test was to see how many of the earliest words they recalled.
After the treatment, nearly all the participants did better on memory tests than they had before and better than controls. People who scored worse at the beginning showed the most improvement. And memory benefits remained a month later, according to a new study from Boston University, published Monday in the journal Nature Neuroscience.
Although still in its early days, with lots of steps before such technology could be fully tested and become widely available, its implications are immense.
As people age, even without diseases like dementia, everyone becomes more forgetful, misplacing their car keys or even their car, struggling to learn new information and finding planning more difficult.
A simple treatment with electrical pulses that could prevent decline or potentially restore some of these functions could dramatically improve lives.
Researchers are still figuring out the right “dose” and how long the benefits might last, but they hope that eventually their technology could become available for at-home use.
The study looked at people ages 65-88, most suffering typical memory loss or mild cognitive impairment, a precursor to dementia. The researchers are also exploring the technology to treat people with schizophrenia-associated memory loss and with obsessive-compulsive behaviors.
Theoretically, the same approach should also help healthy people boost their memory, though that hasn’t been the focus of the team’s latest work.
But it might be trickier to use in cognitively normal people, said Ivan Alekseichuk, a research scientist at the University of Minnesota, who was not involved in the study but conducts similar research.
Forgetting is an important part of working memory, he said. “Forgetting something is not a bug of memory, it’s a feature,” he said. “You have to forget in order to learn. You don’t want to overly improve memory in people who are otherwise healthy.”
DOES EXERCISE STAVE OFF ALZHEIMER’S? Even stretching and balance movements can help, study says.
The cap’s electrodes deliver weak electrical pulses to specific areas of the brain previously known to be involved in different types of memory.
Delivering these pulses to prefrontal cortex at high frequency selectively improved the test subjects’ ability to remember words from the beginning of the word list. Applying the same specialized alternating current to the parietal cortex, farther back in the brain at a low frequency improved just their short-term memory.
The energy oscillations trigger brain cells to activate, restoring their “plasticity,” or ability to change. This also allows them to carry the improvements forward, even though the simulation ends, said Shrey Grover, the Ph.D candidate who led the research.
The stimulation was delivered while participants were doing a specific task, so it probably improved the connection between different brain areas responsible for that task, said Alekseichuk, a biomedical engineer. Once the connection is made, it lasts for at least a month.
It’s not clear whether the approach really boosted long-term memory, which typically requires someone to remember something for at least a day, he said.
But it definitely improved the participant’s “working memory,” which is what people rely on to get through their daily lives. “This is extremely exciting,” he said.
It’s hard to compare how someone performs on a laboratory test to how they will act in the real world, said Robert Reinhart, the paper’s senior author and director of Boston University’s Cognitive & Clinical Neuroscience Laboratory.
But the effects were “moderate to large,” he said, suggesting the treatment would offer quality of life benefits. He hopes to address real-world improvements in a future study.
The rate each person improved after the four treatment days predicted the size of their memory benefit a month later. “Based on how well you respond to the treatment, we can be reasonably confident in how long-lasting the benefits will be for each individual,” Reinhart said.
Even people who have lost brain cells to Alzheimer’s may have enough structure left to lead to memory improvements, Grover said.
In a 2019 study, Reinhart showed that similar brain modulation could improve visual-spatial memory, which includes the ability to recall shapes and colors in addition to their locations and movements. This study focused on auditory-verbal memory, which generally deteriorates with age.
The new research also showed that the treatments offer a cumulative benefit, with four days providing substantially more benefit than one, Reinhart said.
The field has long debated whether short- and long-term memory storage are distinct phenomenon. By manipulating them separately, the research suggests they are different, Grover said.
For people with certain conditions, like Parkinson’s disease, which reduces short-term memory or medial-temporal lobe epilepsy which affects long-term memory, being able to selectively target and improve these memory systems could be useful, Reinhart said.
Dr. Cameron Carter, a cognitive neuroscientist at the University of California, Davis, said he definitely sees potential for using this approach to treat – or even prevent – schizophrenia and other psychotic illnesses.
People with these conditions show signs of cognitive deficits even before their illness becomes apparent, said Carter, who was not involved in the new study. If they were treated early, it might disrupt the disease process. “It could make a big difference,” he said, though more research is needed to prove its effectiveness.
Transcranial magnetic stimulation is a similarly noninvasive procedure that directs magnetic fields to stimulate nerve cells. In repeated treatments, typically over 4 to 6 weeks, a magnetic coil is placed against the skull, often to treat depression.
Reinhart said his technique, transcranial alternating current stimulation, is different because it’s so low dose that it’s a “modulatory not a stimulatory approach.” The stimulator is relatively inexpensive, safe, lightweight and easy to use, which is why he is optimistic that it will be available for treatment, not just research, at some point.
Cognitive training, which is intended to boost memory, has shown mixed effectiveness, Grover said, though remaining engaged socially and intellectually is clearly good for the aging brain. The pair see their treatments as a complement not a substitute for activities that engage the brain.
People reported feeling things like itching, tingling, poking and warming as the device ramps up or down, for the first and last 30-60 seconds of treatment, Reinhart said.
In other trials, some participants have complained of mild headache or fatigue, but that wasn’t seen in the current study. He and others trying similar approaches have seen no worrisome or lingering side effects.
WILL POLIO SPREAD LIKE COVID-19? Experts say it’s unlikely but the unvaccinated are still at risk.
This study only followed people for a month after the treatment. Other studies using similar approaches have found that benefits can continue for as long as three months and Grover said he’s optimistic the improvements will last that long, but he has to confirm with further research.
Reinhart hopes that further research will help determine how to make treatments endure and whether repeat treatments will be equally effective.
The team is still figuring out how personalized the treatment needs to be. It’s possible that by better targeting the electrical pulses, they might be able to generate longer-lasting or more significant improvements, but they’re still working that out.
Alekseichuk said personalization might improve effectiveness, but perhaps not enough to justify its added cost, which he estimated at at least 10-times more than the $15,000 current cost of the device. The fact that researchers saw improvement without personalizing the therapy was “highly exciting,” he said.
There may be less expensive ways to personalize it, by varying the time interval between the sessions or even the time of day they are delivered, with morning people getting treated at different times that “owls.”
At some point, the team will also explore whether the treatment can augment the abilities of healthy people.
“These type of tools, were they to become available to the general population would be of interest for boosting cognition,” Reinhart said. In coping, say, with the jet lag of international travel, instead of drinking coffee, “you can imagine a future, potentially where people are using (electrical) stimulation.”
To volunteer for the research, contact the lab at cogneuro@bu.edu or 617-358-8110.
Contact Karen Weintraub at kweintraub@usatoday.com.
Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.
