02 May 2019

Brain 'zap' might rejuvenate ageing memory

The memory of people aged 60 to 76 equalled that of twenty-somethings after they got 25 minutes of electrical stimulation to specific regions of their ageing brains.

It's common for folks to become less sharp as they age, taking a little longer to do maths in their heads or work out a knotty problem. But scientists might have a potential solution.

Brain stimulation using extremely weak electrical current might be able to reverse this and restore youthful vigour to ageing minds, a new laboratory study suggests.

Age-related effects not unchangeable

The memory performance of people aged 60 to 76 equalled that of twenty-somethings after they got 25 minutes of electrical stimulation to specific regions of their ageing brains, researchers found. Working memory is the ability to temporarily retain information needed for processing.

The effect lasted for at least 50 minutes after the brain stimulation stopped and likely extends for hours longer, said lead researcher Robert Reinhart. He's an assistant professor of psychological and brain sciences at Boston University.

The results were also similar to those seen in a group of people in their 20s, the study authors said.

The study results not only provide new insights into age-related working memory decline, "but they also show us that the negative age-related effects are not unchangeable," Reinhart said. "We can bring back the more superior working memory function you had when you were much younger."

Working memory is a fundamental building block of the human thought process, he explained.

"It's been called … the workbench of the mind or the sketch pad of the mind. It's where people reason, problem solve, plan and make decisions," Reinhart said.

Unfortunately, this "fragile and precious cognitive resource" declines as you get older, he added.

Synchronising brainwaves

Reinhart and his colleagues suspect this decline occurs because different brain regions involved in working memory become out-of-sync with one another. The brain operates through rhythmic waves of electrical impulses, and if those impulses lose their rhythm, the ability to think can become disordered as well.

To test this, they designed a special EEG (electroencephalogram) cap. It contains electrodes that direct low-level electrical current to the neocortex and frontal lobes – the brain regions that play a major role in working memory, Reinhart said.

"These are evolutionarily the most advanced parts of the human brain," he noted. "They're what make us special as humans."

This electrical stimulation is intended to synchronise the brainwaves among the different regions of the brain, allowing them to better communicate and work together, the study authors said.

The researchers tested the cap on 42 older adults (aged 60 to 76), asking them to perform working memory tasks with and without brain stimulation on separate days. The sensors allowed the researchers to precisely tune the stimulation to the individual electrical frequencies in each person's brain.

"During stimulation, the person would experience some slight tingling, itching or poking sensation roughly underneath the electrodes that are delivering the electrical current," Reinhart said, adding that the feeling went away after half a minute as people got used to it.

Effect may be longer lasting

While receiving active brain stimulation, the seniors' working memory improved to the level of adults aged 20 to 29 who performed the same tasks as a "control" group, the investigators found.

The improvements in brain function were correlated with increased brainwave interactions in the left temporal and prefontal cortex, the findings showed.

Although the researchers only tracked brain activity for 50 minutes following stimulation, Reinhart believes that the effect is longer lasting.

"We didn't see the effects coming down to baseline or even trending down to baseline levels, so my guess is the effects last longer than 50 minutes," Reinhart said. "We just haven't done that duration experiment to see exactly when they do come down to baseline."

Electrical stimulation already is used to improve motor function in patients with Parkinson's disease, so it's not out of the realm of possibility to think this could also boost a person's ability to think and reason, said Keith Fargo, director of scientific programmes and outreach at the Alzheimer's Association.

More research needed

"Ultimately, brain is brain. Sometimes the output you want is the correct motor movement, and sometimes the output is answering correctly on a memory test," Fargo said.

"The concept is sound," he added. "It's not crazy that this could work in dementia."

However, Fargo cautioned against getting too enthusiastic, since a lot more research is needed before this becomes available to the public.

"People who read about this, I don't want them to think they can go to the doctor the next week and receive a stimulating treatment, but it is possible in the future something like that might occur," Fargo said. "It's still pretty far away from the clinic."

The study was published online in the journal Nature Neuroscience.

Image credit: iStock


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