Brain Stimulation Shows Promise for Understanding Memory Decline in Older Adults

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In a small, pilot study, a non-invasive device that uses magnetic fields to stimulate nerve cells in the brain was associated with temporary improvements in age-related memory loss in older people, according to a study published in Neurology.

The study found that transcranial magnetic stimulation temporarily increases activity in regions of the brain that help create, store and retrieve memories called the hippocampal-cortical network. Study participants also scored better on memory tests after receiving stimulation, although the results were temporary.

The device uses an electromagnetic coil that is held next to the scalp, delivering short bursts of magnetic energy to targeted areas of the brain. The same device is currently FDA approved to treat depression when other treatments are not successful.

“As we get older, our brains age too, and these changes mean our brain may not work as efficiently, so it is normal to experience some mild forgetfulness,” said study author Joel L. Voss, PhD, of Northwestern University in Chicago. “With stimulation, we were able to essentially excite the areas of the brain that are involved in memory formation in older adults, improving their ability to recall items as well as younger adults. It is important to note that while our small study examined age-related memory loss, it did not examine this stimulation in people with memory loss from more serious conditions such as mild cognitive impairment or Alzheimer’s disease.”

The study involved 15 people with an average age of 72 who had normal thinking skills but impaired memory at the start of the study when compared to a group of young adults with an average age of 25 who performed the same memory task. Participants received the stimulation once a day for five days in a row. Then the following week they received stimulation at a dose not high enough to have any effect as a placebo, or sham, treatment. Participants did not know which treatment they were receiving at the time, although the researchers knew. The memory task measured their ability to recall objects and how they were related to each other.

Participants were given the memory test at the start of the study, one day after treatment ended and again one week after the end of treatment. Researchers also used magnetic resonance imaging (MRI) to measure the brain activity of each participant at the same time periods before, during and after treatment.

Researchers found that when tested 24 hours after the treatments ended, participants’ ability to recall memories improved 31 percent when compared to their abilities at the beginning of the study. MRI imaging also showed more activity in the regions of the brain involved in memory formation. Out of 84 questions on the memory test, participants answered an average of 33 questions correctly before stimulation. After stimulation, they answered an average of 10 more questions correctly.

“Memory improvements were highly consistent for participants after receiving stimulation, and participants were able to recall memories just as well as the group of young adults to whom they were compared at the start of the study, but the gains were temporary,” said Voss.

When participants were tested again one week after the treatments ended, there were no differences between when they received the stimulation and when they received the sham treatment.

He noted, “Disruption and abnormal functioning of the hippocampal-cortical network, the region of the brain involved in memory formation, has been linked to age-related memory decline, so it’s exciting to see that by targeting this region, magnetic stimulation may help improve memory in older adults. These results may help us better understand how this network supports memory.”

It is important to note that this study was designed to examine which areas of the brain should be targeted with stimulation and not to evaluate how effective the treatment may be.

Limitations of the study include the small number of participants. Future studies must now investigate whether this stimulation shows similar results in much larger groups of people, if memory gains can be retained over longer periods of time and if the stimulation can help people with more severe damage to the memory formation network in the brain.

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