According to researchers at Boston University in Massachusetts, adults whose brains have been stimulated with low-level electrical currents for several days improve memory significantly. This has been shown by a study published in Nature Neuroscience by a research team led by neuroscientist Robert Reinhart. The study was conducted on 150 people between the ages of 65 and 88.

Previous studies have already shown that different areas of the brain are involved in long-term and working memory. According to the researchers, the stimulation of the dorsolateral prefrontal cortex with high-frequency electrical currents should improve long-term memory. Low-frequency electrical stimulation of the lower parietal lobe increases working memory performance. While people can store information in the long-term memory for a longer period of time, the working memory is used, among other things, for the short-term absorption of information.

tACS is non-invasive

The study used non-invasive transcranial alternating current stimulation (tACS). Electric currents reach the brain through electrodes on the surface of the scalp. Participants performed a memory task in which they were asked to recall lists of 20 words each that had been read aloud. During the 20-minute task, tACS was applied.

After four consecutive days, participants with high-frequency stimulation of the left prefrontal cortex had an improved ability to memorize words from the top of lists. Low-frequency currents in the lower left parietal lobe improved recall of words that were at the bottom of the list. This is where working memory came into play. The participants’ memory performance improved over the four days and continued a month later. Memory improvements were greatest in those who had the lowest cognitive abilities prior to the study.

method already tested

According to Prof. Dr. Sabine Weiss from the Experimental Neurolinguistics group at Bielefeld University can be increased by taking into account the individual physiological state – for example the frequency – of the brain shortly before the stimulation, such as studies by research groups at the University of Göttingen and the Charité in Berlin and the University of Oldenburg showed.

In future studies, the research team plans to investigate whether memory improvements can last longer than a month and whether the benefits of brain stimulation can be generalized to other types of memory tasks. In addition, future research is to be carried out into the extent to which tACS can also help with diseases such as Alzheimer’s dementia.