The first results are promising for two types of memory performance. But experts see limits to medical use.
On which conveyor belt can one pick up the bags? It was just announced. And where did you park the car before the two weekends? On the other hand, so-called “working memory” provides answers – to baggage information that has just been transferred. On the other hand, long-term memory stores information about the drive home in your own car.
This brain functioning develops quite differently in people and tends to decline with age. A recent study in healthy older adults showed that electrical stimulation of the brain can improve both types of memory performance.
A research team led by Shree Grover and Robert Reinhart of Boston University says this could make daily activities easier for people in many countries due to an aging population. Electrical brain stimulation for four consecutive days was able to improve memory performance in people over 65 years of age for one month, The researchers report in the journal Nature Neuroscience..
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Tickling sensation on the scalp
For the study, electrical currents were conducted through electrodes in a cap worn by 150 participants between the ages of 65 and 88. The test subjects unanimously reported a tickling sensation on the scalp at the start of the stimulation. This method is known as transcranial alternating current stimulation, which stimulates brain vibrations and is said to enhance what is known as neuroplasticity. These are the experience-related changes in the brain that form the basis of learning and memory.
During the 20-minute sessions, participants listened to lists of 20 words to memorize. The researchers targeted two brain regions with two different stimulation frequencies: stimulation of the inferior parietal lobe at a frequency of four Hz improved word recall at the end of the list – an indicator of storage in working memory. Stimulation of the dorsolateral prefrontal cortex at 60 Hz favored recall of words at the top of the list, indicating long-term memory retention.
Participants with lower cognitive performance at the start of the study benefited the most from brain stimulation. Additional investigations should show if the recorded effects persist for more than a month. The authors suggest exploring the implications for people with neurological, psychiatric, and neurodegenerative disorders, as well as the potential benefits for healthy older adults.
“Little practical use of the clinic”
“The experimental approach is not complicated,” said Wolf-Julian Neumann, a neurologist from the German Science Media Center (SMC) in Berlin Charité. In the future, these technologies can be used at home as well. “However, it is currently not possible to derive any direct therapeutic approach from this study, since the demonstrated effect is very specific and small.” They limit themselves to repeating words that have been read aloud. The effect has only been demonstrated for learning during electrical stimulation.
Johannes Levine of the German Center for Neurodegenerative Diseases wonders what the purpose of treating cognitively healthy people with electrical brain stimulation is. Although the study’s authors had notable results in the area of language memory performance, this “in this situation is like improving brain performance rather than a real treatment,” Levine told SMC. The authors also did not study whether people’s quality of life improved.
“In my opinion, this is not a practical use for a clinic,” says Paul Lingor, a neurologist at the Technical University of Munich. One might wonder if traditional cognitive training is not as effective or better and would have other positive effects as well.
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