Scientists discovered that periodic burst of electricity may be able to reverse memory deficits in older people, according to a new study published on 8 April in Nature Neuroscience (1). The researchers from Boston University focused on so-called working memory, the part of short-term memory responsible for temporarily holding information. And an essential component of reasoning and decision making.
How does age affect working memory?
Neurons in the brain generate electrical waves that allow information to be stored for as long as needed. Although information is only stored for a matter of seconds, short-term memory is critical to performing everyday tasks, including reading and writing, and even counting. Scientists believe millions of neurons located across the brain cooperate to accomplish short-term memory processes.
Although scientists previously reported age differences in brain activity, it is still unclear how these differences relate to cognitive performance (2). But they might be linked to the uncoupled activity of electrical waves in different parts of the brain in older people.
Nonetheless, memory loss is a “core feature” of cognitive decline in older people. With age, the electrical impulses that control brain waves become less coordinated causing short-term memory deficits.
Boosting working memory with electrical stimulation
Scientists previously reported a boost in working memory using electrical stimulation. However, this is the first time the approach has been demonstrated in an older population.
The researchers used something called transcranial alternating-current stimulation to synchronize the brain waves of 42 healthy volunteers between the ages of 60 and 76. The weak electrical pulses synchronise two areas of the brain involved in cognition, the prefrontal and temporal cortex.
At the same time, they recorded brain waves of the participants before and after the stimulation using electroencephalographic (EEG) measurements. Then to test changes in cognitive performance, the participants were asked to spot the differences in sets of images before and after electrical stimulation.
After only 25 minutes of electrical stimulation, older participants identified differences more accurately and their performances matched those of a much younger test group of healthy adults in their 20s. The positive effects lasted throughout the duration of the test ― nearly one hour ― but may last even longer. Furthermore, previously out-of-sync electrical impulses in the prefrontal and temporal cortex started to fire in sync.
Interestingly, the researchers were also able to reduce the working memory of younger participants by using the electrical stimulation to knock the brain impulses out of sync.
The new study has effectively demonstrated that brain waves can affect the working memory of older people. Importantly, it has “laid the groundwork for future non-pharmacological interventions targeting aspects of cognitive decline,” the authors write.
The researchers have not shown any evidence of potential clinical benefits of using this approach just yet. However, they hope to further explore technologies like this as potential treatments for diseases linked to working memory such as Alzheimer’s.
(1) Reinhart, R.M.G. and Nguyen, J.A. Working memory revived in older adults by synchronizing rhythmic brain circuits. Nature (2019). DOI: 10.1038/s41593-019-0371-x
(2) Grady, C. The cognitive neuroscience of ageing. Nature Reviews Neuroscience (2012). DOI: 10.1038/nrn3256