Although it is said that with age comes wisdom, the harsh reality is that ageing also leads to a progressive deterioration of brain function. Certain aspects of perception, memory, and attention seem to be the most significantly affected, which can set the stage for dreadful accidents among the elderly. Luckily, various experimental protocols are being tested as potential ways to mitigate or even reverse age-related cognitive decline.
One such protocol is called transcranial direct current stimulation (tDCS). This non-invasive procedure involves using electrodes to circulate small electrical currents through specific parts of the brain, modulating neuronal activity. While many studies have reported that tDCS can improve the cognitive capabilities of the elderly, it has proven difficult to rigorously quantify and compare these improvements between studies because of the different methodologies and experimental paradigms used.
To help fill this knowledge gap, a team of scientists from Incheon National University, Korea, conducted a meta-analysis of previously published studies on tDCS as a technique to improve cognitive performance. Unlike existing meta-analyses, the researchers assessed the improvement produced by tDCS by comparing the changes in reaction time during various cognitive tasks. This essentially circumvented the problem posed by the large heterogeneity in the methodologies used for tDCS research. This paper was made available online on June 2 nd , 2021, and was published in Volume 70 of Ageing Research Reviews in September 2021 .
After searching for and filtering relevant tDCS studies, the team ended up with 31 qualifying papers involving 934 healthy adults. They categorized the studies based on the cognitive domains targeted by the tasks given to the subjects, such as perceptual–motor function, learning and memory, executive function, and language. Additionally, the researchers analyzed if the timing of the tDCS was relevant; that is, if applying tDCS before or during the tasks had different effects in reaction time.
The results of the statistical analyses conducted by the team indicate that applying tDCS during the tasks produced a small yet significant improvement in reaction times, specifically in learning and memory tasks and executive function/complex attention tasks. This improvement was more pronounced in older people, suggesting the positive effects derived from tDCS increase with age. “ Our meta-analysis extends prior findings that suggested tDCS protocols could improve cognitive functions and effectively increase cognition-related neural processing speed, ” remarks Associate Professor Nyeonju Kang, who led the study.
Overall, this study highlights tDCS as an effective therapeutic option for improving the lives of the elderly. “ If we prove tDCS protocols effectively enhance cognitive functions, home-based tDCS programs could be developed to prevent the progression of age-related cognitive deficits, thereby increasing life satisfaction among the elderly population ,” concludes Dr. Kang.
Let us hope further research helps us understand the true potential of tDCS even better!
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Reference
Authors: Joon Ho Lee 1,4 , Tae Lee Lee 1,4 , Nyeonju Kang 1,2,3,4
DOI: https://doi.org/10.1016/j.arr.2021.101377
Affiliations:
About Incheon National University
Incheon National University (INU) is a comprehensive, student-focused university. It was founded in 1979 and given university status in 1988. One of the largest universities in South Korea, it houses nearly 14,000 students and 500 faculty members. In 2010, INU merged with Incheon City College to expand capacity and open more curricula. With its commitment to academic excellence and an unrelenting devotion to innovative research, INU offers its students real-world internship experiences. INU not only focuses on studying and learning but also strives to provide a supportive environment for students to follow their passion, grow, and, as their slogan says, be INspired.
Website: http://www.inu.ac.kr/mbshome/mbs/inuengl/index.html
About the author
Dr. Nyeonju Kang received his Ph.D. from the College of Health and Human Performance at the University of Florida in 2015 under the mentorship of Dr. James H. Cauraugh. He was appointed as an Assistant Professor at the Division of Sport Science of Incheon National University, Korea, in 2017, and promoted to Associate Professor in September 2021. He founded the Neuromechanical Rehabilitation Research Laboratory, and his current research focuses on the neurorehabilitation of stroke and ageing populations using isometric force control paradigms, motor unit physiology, non-invasive brain stimulation, and meta-analysis, supported by National Research Foundation, Korea.
Website: https://sites.google.com/view/nj-nml-inu
Ageing Research Reviews
Transcranial direct current stimulation decreased cognition-related reaction time in older adults: A systematic review and meta-analysis
1-Sep-2021