Memory or loss of memory is a big concern for many seniors. We can improve our working memory, working
memory - our capacity for holding information in mind at any given moment -
underlies many fundamental cognitive processes and is linked with some aspects
of intelligence. Research has shown that working memory training improves
working memory performance but it's unclear whether one type of specific training that is now being used can
yield improvements to broader cognitive abilities
This training is called transcranial
direct-current stimulation (tDCS) - a non-invasive technique for applying
electric current to areas of the brain. This type of training is growing in popularity, but new
research suggests that it probably does not add any meaningful benefit to
cognitive training. The study is published in Psychological Science, a journal
of the Association for Psychological Science.
"Our
findings suggest that applying tDCS while older participants engaged in daily
working memory training over four weeks did not result in improved cognitive
ability," explains researcher Martin Lövdén of Karolinska Institutet and
Stockholm University.
"The
study is important because it addresses what has arguably been the most
promising cognitive application of tDCS: the possibility of long-term cognitive
enhancement from relatively limited practice on select cognitive tasks,"
Lövdén adds. "Cognitive enhancement is of interest not just to scientists,
but also to the student studying for final exams, the gamer playing online
games, and the retiree remembering which pills to take. Because of this large
audience, it is of utmost importance to conduct systematic research to
disentangle hype from fact."
The
researchers enrolled 123 healthy adults who were between 65 and 75 years old in
a 4-week training program. All participants completed a battery of cognitive
tests, which included tasks that were incorporated in the training and tasks
that were not, at the beginning of the study and again at the end. Those
randomly assigned to the experimental group trained on tasks that targeted
their ability to update mental representations and their ability to switch
between different tasks and rules, while those in the active control group
trained on tasks that focused on perceptual speed.
As
they completed the training tasks, some participants received 25 minutes of
tDCS current to the left dorsolateral prefrontal cortex, an area of the brain
that plays a central role in working memory; other participants were led to
believe they were receiving 25 minutes of current, when in actuality the
current was only active for a total 30 seconds.
Comparing
participants' performance before and after training indicated that those who received
working memory training did improve on the updating and switching tasks they
had encountered during training and on similar tasks that they had not
encountered previously.
But
there was no evidence that tDCS produced any additional benefit to the working
memory training - at the end of the study, participants who received tDCS did
not show greater improvement than their peers.
When
the researchers pooled the data from this study with findings from six other
studies, they again found no evidence of any additional benefit from working
memory training that was combined with tDCS.
Given
strong public interest in cognitive enhancement, Lövdén and colleagues urge
caution when it comes to this as-of-yet unproven application of tDCS:
"A
growing number of people in the general public, presumably inspired by such
uninhibited optimism, are now using tDCS to perform better at work or in online
gaming, and online communities offer advice on the purchase, fabrication, and
use of tDCS devices," the researchers write. "Unsurprisingly,
commercial exploitation is rapidly being developed to meet this new public
demand for cognitive enhancement via tDCS, often without a single human trial
to support the sellers' or manufacturers' claims."
"These
findings highlight exactly how limited our knowledge is of the mechanisms
underlying the potential effects of tDCS on human cognition and encourages the
research community to take a step back and focus its resources on developing
strategies for uncovering such mechanisms before using the technique in more
applied settings," Lövdén concludes.
Article:
Direct-Current Stimulation Does Little to Improve the Outcome of Working Memory
Training in Older Adults, Jonna Nilsson, Alexander V. Lebedev, Anders Rydström,
Martin Lövdén, Psychological Science, doi: 10.1177/0956797617698139, published
16 May 2017.
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