Electrical stimulation in the brain improves memory in the elderly, research indicates

Electrical brain stimulation improved immediate and long-term memory in elderly volunteers, with benefits lasting more than a month, in experiments conducted at Boston University in the United States.

Robert Reinhart, head of the project, said the findings could form the basis for treatments that do not involve drugs or invasive neurotechnology to boost cognitive performance in people who develop Alzheimer’s disease and other disorders characterized by impaired memory.

The Boston researchers directed weak alternating currents to specific regions of the brain, using electrodes in cranial “caps” worn by the participants. They worked with 150 people over age 65, who were given 20 minutes of stimulation a day for four days and listened to lists of words they were asked to remember.

Short-term or working memory—indicated by immediate recall of words—improved 65% after the four days and was still 40% better a month later without further stimulation.

Long-term memory — remembering words minutes or more after hearing them — was 50% better after four days and 37.5% better one month after the last electrical stimulation. The results were published this Monday (22) in the journal Nature Neuroscience.

Reinhart sees non-invasive neurostimulation as a potential treatment for memory loss in the elderly and particularly those who develop dementia. No adverse side effects were reported, other than “a certain itching and tingling sensation for approximately 30 to 60 seconds at the beginning of stimulation and for 30 to 60 seconds at the end”.

“The work has obvious clinical implications,” he said. “Older people with general cognitive impairment who participated in the experiment were the subjects who showed the greatest improvements both during the intervention and at the one-month point. [Esse] is a good omen to transfer [o procedimento] for a suitable clinical study in people with Alzheimer’s disease who suffer from more severe memory impairment.”

The electrical stimulation was targeted at two alternative brain regions: the prefrontal cortex, known to be associated with long-term memory, and the parietal cortex, further back in the brain, which is more involved in short-term memory. To create a control group, some volunteers were subjected to a “sham” or placebo procedure, in which they wore the same caps as those subjected to the active stimulus, but without the electrical stimulation being directed to any region of the brain. Participants did not know which group they were in.

The researchers then read strings of 20 unconnected words to the participants. They examined how likely people were to recognize the most recently heard words at the end of the list, which is correlated with short-term memory, or at the beginning of the list read to them minutes earlier, which is an indicator of long-term memory. .

Masud Husain, a professor of neuroscience at the University of Oxford, who was not involved in the research, said “these results are very exciting” but stressed that the scope of the study was limited.

“We have to keep in mind that the effects on memory were on the order of remembering three or four more words out of a list of 20, but this improvement was detectable one month after stimulation, which is quite remarkable,” he said. “Whether these improvements would occur for everyday memories rather than just word lists remains to be tested,” he added.

Reinhart said the Boston University team now intends to focus their work on “real world” cognitive activities.

“We are now involved in linking our laboratory brain and behavioral measures to functional outcomes like… measures of activities of daily living,” he said. “[Elas] are most relevant to reducing the severe social and economic impact of impaired cognition that comes with age and mental illness.”