At which conveyor belt can one still pick up the suitcases? It was just announced. And on which parking deck did you park the car before the two-week vacation? On the one hand, the so-called “working memory” provides answers – for the luggage information that has just been passed on. The long-term memory, on the other hand, stores the information for the drive home in your own car.
This brain performance is very differently developed in people and tends to decrease with age. A recent study with healthy older people now shows that non-invasive electrical brain stimulation can improve both types of memory performance.
A research team led by Shrey Grover and Robert Reinhart from Boston University says that this could make everyday activities easier for people in many countries in view of the aging of the population. Electrical brain stimulation on four consecutive days was able to increase the memory performance of people aged 65 and over for one month, the researchers report in the journal “Nature Neuroscience”.
For the study, electrical currents were conducted via electrodes into a cap worn by the 150 participants between the ages of 65 and 88. The test persons unanimously reported a tickling sensation on the scalp at the beginning of the stimulation. The method is known as transcranial alternating current stimulation, which stimulates brain oscillations and is said to promote 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, subjects listened to lists of 20 words to memorize. The researchers targeted two brain regions with two different stimulation frequencies: Stimulating the inferior parietal lobe at a frequency of four Hertz improved the recall of the words at the end of the list – an indication of storage in working memory. Stimulating the dorsolateral prefrontal cortex at 60 Hertz favored the recall of the words at the top of the list, indicating long-term memory retention.
The participants with the lowest cognitive performance at the start of the study benefited the most from brain stimulation. Further investigations should show whether the recorded effects last beyond a month. The authors suggest exploring the implications for people with neuropsychiatric and neurodegenerative disorders, in addition to the potential benefits for healthy older adults.
“The experimental approach is not complex,” said Wolf-Julian Neumann, neurologist from the Berlin Charité the Science Media Center Germany (SMC). In the future, such technologies could potentially be used at home as well. “However, no direct therapeutic approach can currently be derived from this study, since the effect shown is very specific and small.”. They limit themselves to repeating words that have been read aloud. And the effect has only been proven for learning during electrical stimulation.
Johannes Levin from the German Center for Neurodegenerative Diseases questions the point of treating cognitively healthy people with electrical brain stimulation. Although the study authors achieved remarkable results in the area of language memory performance, this “in this setting resembles brain performance optimization rather than real therapy,” Levin told the SMC. The authors also did not examine whether the quality of life of the subjects improved.
“In my opinion, this is not very practical use for the clinic,” says Paul Lingor, a neurologist at the Technical University of Munich. One might ask whether conventional cognitive training is not just as effective or better and would have other positive effects as well.