Claims magnetic brain stimulation helps memory
“Magnetic brain stimulation treatment shown to boost memory,” The Guardian reports. A new study found that magnetic pulses improved recall skills in healthy individuals. It is hoped that the findings of this study could lead to therapies for people with memory deficits such as dementia.
Researchers investigated the effects of transcranial magnetic stimulation (TMS) every day for five days on connections within the brain and on associative memory (the ability to learn and remember relationships between items – such as “1066” and the “Battle of Hastings”).
TMS is a non-invasive technique that uses an electromagnet placed against the skull to produce magnetic pulses that stimulate the brain.
In this study, TMS of a specific area of the brain was compared to “sham” stimulation in 16 healthy adults.
TMS was found to improve performance on the associative memory test by over 20%, whereas sham stimulation had no significant effect.
While the results are interesting, there are important limitations to consider. The sample size was small, just 16 people, so the findings need to be replicated in a larger group of people. It is also unclear how long any effect would persist, and if there are any adverse effects of TMS. Long-term studies are also required to determine whether TMS is both safe and effective.
Of note, the current study involved healthy people, not people with memory deficits, so it is uncertain whether TMS would be of any benefit to people with conditions that cause memory deficits such as dementia.
Where did the story come from?
The study was carried out by researchers from Northwestern University and the Rehabilitation Institute of Chicago, and was funded by the US National Institute of Mental Health and National Institute of Neurological Disorders and Stroke.
The study was published in the peer-reviewed journal Science.
The results of this study were generally well reported by the media, although some headline writers overstated the implications of the results.
What kind of research was this?
This was a cross-over trial that aimed to determine whether electromagnetic stimulation of a particular region of the brain could improve memory in 16 healthy people.
The researchers were interested in a region of the brain called the hippocampus, which is necessary for associative memory – this includes the ability to remember the association between a word and a face. It has been hypothesised that this ability also depends on other brain regions, and that the hippocampus could act as a “hub”.
To see whether this was the case, the researchers used high-frequency TMS to stimulate part of the brain known as the lateral parietal cortex, which is thought to interact with the hippocampus in memory.
The lateral parietal cortex is part of the cerebral cortex or grey matter, and the hippocampus is located under grey matter.
What did the research involve?
The researchers compared the effects of high-frequency transcranial magnetic stimulation and “sham” stimulation for five days on the ability of 16 healthy people to remember the association between faces and words.
Each person participated for two weeks – one week with TMS and one week with sham stimulation – separated by at least one week. The baseline assessment occurred one day prior to the first stimulation session, and there were five consecutive daily stimulation sessions. The post-treatment assessment occurred one day after the final stimulation session. Half the subjects received TMS first and half received sham stimulation first.
In the memory test, participants were shown 20 different human face photographs for three seconds each. A researcher read a unique common word aloud for each face. One minute after this had been completed the participants were shown the photos again and asked to recall the words associated with them.
In addition to looking at the effect of memory, the researchers also looked at the effect of TMS on connectivity within the brain, using a technique called functional magnetic resonance imaging. This technique looks at changes in blood flow, and can be used to assess connectivity by looking for variations in blood flow that are time correlated across the brain.
What were the basic results?
TMS improved people’s ability to remember the association between a word and a face by more than 20%, whereas sham treatment caused no significant performance change.
The researchers also gave people other cognitive tests, but found that TMS had no effect on people’s performance on these tests.
TMS also increased connectivity between specific cortical (grey-matter) regions of the brain and the hippocampus.
How did the researchers interpret the results?
The researchers concluded that cortical-hippocampal networks can be enhanced noninvasively and play a role in associative memory.
Conclusion
In this study, TMS was found to improve performance on the associative memory test by more than 20%, whereas sham stimulation had no significant effect.
TMS also increased connectivity between specific cortical (grey-matter) regions of the brain and the hippocampus.
This interesting research increases our knowledge of how memory works. However, it was a very small trial with only 16 participants. It is also unclear whether electromagnetic stimulation would be effective for people with memory disorders such as dementia. The media has reported that the researchers are now planning to study the effect of TMS on people with early loss of memory ability.
Long-term studies are also required to determine how long the improved memory performance lasts and to ensure that electromagnetic stimulation of the brain doesn’t have any adverse effects.
Dementia remains a poorly understood condition, and claims that brain training exercises have a definitive protective effect against the condition have not held up to scrutiny. That said, keeping the brain active through memory intensive activities such as learning a new language, a musical instrument, or even just picking up a book cannot hurt. Keeping the mind active has been shown to improve quality of life.
