NIH Record - National Institutes of Health

Stimulation Improves Memory in Older Adults

A noninvasive stimulation technique targeting specific brain regions resulted in month-long memory improvements in seniors who participated in a recent study. Results were reported in Nature Neuroscience.

Based on earlier research, an NIH-funded research team at Boston University hypothesized that low-frequency stimulation to the parietal region near the back of the brain would improve short-term working memory, whereas high-frequency stimulation to the prefrontal cortex would improve long-term memory.

The team enrolled 150 volunteers, ages 65-88, in a randomized, double-blinded clinical trial and used a technique called high-definition transcranial alternating current stimulation (HD-tACS). The method involves applying weak electrical currents of different frequencies to specific brain regions to help modify and synchronize the brain’s rhythmic activities. 

Participants received 20 minutes of stimulation for 3 or 4 consecutive days. At the start of each session, they donned an electrode-studded skull cap that delivered currents to specific brain regions. The control group received two 30-second pulses of stimulation that generated tingly sensations to mimic those felt in the active treatment groups.

To assess memory during the treatment sessions, researchers read aloud 5 lists of 20 common words. At the end of each list, participants were asked to recall as many words as possible. More recently heard words at the end of the lists involved working memory. Words recalled near the beginning of the list needed to use long-term memory. Memory was also assessed at baseline (before treatments began) and 30 days later.

Participants who received low-frequency stimulation to the back of the brain had improved working memory on the third and fourth days of treatment as well as one month later. Those receiving high-frequency stimulation to the same brain region showed no such improvement.

In contrast, volunteers given high-frequency, but not low-frequency, stimulation to the front of the brain showed improved long-term memory on the second through fourth days of treatment and one month later.

Participants who began the study with poorer cognitive function had greater and more enduring improvements. The findings suggest that the activity and functioning of the aging brain can be sustainably altered and improved by using noninvasive techniques to modify specific brain rhythms. Further study is needed to determine whether such methods can enhance memory function in people with brain disorders and in those at risk for dementia.—adapted from NIH Research Matters 

The NIH Record

The NIH Record, founded in 1949, is the biweekly newsletter for employees of the National Institutes of Health.

Published 25 times each year, it comes out on payday Fridays.

Assistant Editor: Eric Bock (link sends e-mail)

Staff Writer: Amber Snyder (link sends e-mail)