Quirks & Quarks

Cutting-edge experiments show an electrical zap improves memory in older adults

Mild electrical stimulation gives older adults the memory performance of 20-year olds

Mild electrical stimulation gives older adults the memory performance of 20-year olds

An older adult receiving transcranial magnetic stimulation to improve his memory in Dr. Joel Voss's study (Joel Voss)
Listen17:06

Two complementary studies recently found that noninvasive and extremely mild brain stimulation could be used to improve episodic and working memory in older adults.

"We can make these 60 and 70-year-olds look strikingly like our 20-year-old participants," researcher Robert Reinhart told Quirks & Quarks host Bob McDonald.

As we age many aspects of our memory deteriorate. The effects can range from irritating, when we can't remember where we left the car keys, to embarrassment when we forget names in a conversation, to tragedy, in pathological conditions like dementia.

This new research suggests, though, that we we might be able to boost memory in the future with just a simple zap to the brain, and the therapeutic potential of this technology could be huge.

Using magnetic induction to boost neural signals 

The first study used a technique called transcranial magnetic stimulation (TMS) to induce mild neural firing in the brain.

The researchers hoped this stimulation would increase communication between the hippocampus, the region deep within the brain that's critically responsible for episodic or long-term memory, and the cortical network connected to the hippocampus on the outer surface of the brain. 

Joel Voss, an associate professor in the Department of Neurology at Northwestern University, led the 15-person pilot study which looked at adults between the age of 64 and 82 with typical memory deficits.

"What we did in our study was try to influence the network of the hippocampus," explained Voss.  In part this was because these areas on the outer part of the brain were ones their TMS system could accurately target. 

An older adult receiving transcranial magnetic stimulation to improve his long-term memory in Dr. Joel Voss's study (Joel Voss)

The research team stimulated the participants' brains for half an hour a day for five days. They then measured the adults' memory ability 24 hours after the final day of stimulation and found their recall ability on a memory test had improved 31 per cent.

"After stimulation, they were no longer impaired relative to the young adults. In fact, we could no longer tell them apart, statistically, from the younger adults performing the same task," said Voss.

It's still unclear to Voss precisely how simulation is changing the neural activity in the brain and leading to the improvement in memory performace. But he thinks by boosting the signals in the hippocampal network, it's could be making the network more connected, since the opposite has been linked to aging and memory decline.

Putting brain waves back in sync 

The second study, led by Robert Reinhart from the Department of Psychological & Brain Sciences at Boston University, used a different technology, and stimulated different regions of the brain.

Using electroencephalography, or EEG, which records the electrical activity of the brain, Reinhart found evidence that older adults' brain waves were out-of-sync in critical brain regions used by working memory or short-term memory.

Reinhart then tried to ameliorate the problem by using a precise and customizable electrical stimulation technology called "high definition transcranial alternating current stimulation," or HD-tACS for short. This system can deliver tiny currents at specific frequencies to re-sync the out-of-sync brainwaves in the temporal cortex, and between the temporal cortex and prefrontal cortex.

"It's a kind of neurotuning," explained Reinhart.

An undergraduate research participant in the Reinhart Lab is performing a working memory task while receiving HD-tACS that has been customized to her individual brain network dynamics. (Robert Reinhart)

"[Brain waves] are a kind of brain language to communicate with itself to implement a working memory," Reinhart explained. "That's scrambled or disordered in the brains of 60 or 70-year-olds, and it's our hypothesis is that it's related to their working memory impairment."

The prefrontal region is thought to control and monitor information in the working memory, and the temporal area is thought to store and process real-world natural objects.

The team applied current for 25 minutes to 42 older participants' brains, and saw improvements during this time on a memory test that they did before they received stimulation. As in Voss' study, the subjects' performance increased to the point that it was equal to that of 20-year-olds who took the same memory test. The researchers were also able to detect improved sychronization of the participants brain waves.

The memory improvements persisted for at least 50 minutes, which was when they took the last test measurements, but Reinhart thinks it may well have lasted longer. 

What's next?

Both Voss and Reinhart believe additional experiments trying out different stimulation parameters and extending the treatment course, could lead to more potent and long-lasting memory improvements.

While there's much more study to be done to understand these memory improvements and fine-tune the technology, Voss and Reinhart are optimistic that perhaps one day it could be made available to anyone who needs a memory boost.

The technology's impact on people with more serious and pathological memory deficits, like Alzheimer's patients, could also be huge, and Reinhart is pursuing that now in his lab.

He says there's a lot of interest from the public and from the science community to develop an intervention to improve memory deficits in Alzheimer's.

"We're working on getting the infrastructure in place now so we can conduct those research studies."

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