Noninvasive Brain Stimulation May Boost Memory

Transcranial alternating current stimulation (tACS) for 20 minutes over 4 consecutive days can improve both short- and long-term memory for at least 1 month in older adults, new research suggests (Nat Neurosci. Published online August 22, 2022).

The effects were moderate to large and the overwhelming majority of participants, 85% to 90%, experienced the memory benefit

The study included 150 adults aged 65-88 years, most of whom had typical memory loss or mild cognitive impairment (MCI). Electrical currents were delivered through electrodes embedded in a cap worn by participants.

On the basis of prior research, the investigators targeted two specific brain regions with two distinct stimulation frequencies.

Targeting the inferior parietal cortex at a low frequency of 4 Hz selectively improved working (short-term) memory, without changing long-term memory.

Targeting the dorsolateral prefrontal cortex at 60 Hz selectively improved long-term memory, without changing short-term memory.

Based on the spatial location and the frequency of the electrical stimulation, we can improve either short-term memory or long-term memory separately.

The rate of memory improvement during the 4-day intervention predicted the size of the memory benefit at the 1 month timepoint.

The researchers note the participants with the lowest cognitive performance at baseline benefited the most from brain stimulation during the process and 1 month later.

The investigators plan to continue their research to examine whether the effects last beyond 1 month and assess functional outcomes of the brain stimulation-induced memory improvements.