TY - JOUR
T1 - A Systematic Review of Transcranial Direct Current Stimulation in Primary Progressive Aphasia
T2 - Methodological Considerations
AU - Coemans, Silke
AU - Struys, Esli
AU - Vandenborre, Dorien
AU - Wilssens, Ineke
AU - Engelborghs, Sebastiaan
AU - Paquier, Philippe
AU - Tsapkini, Kyrana
AU - Keulen, Stefanie
N1 - Funding Information:
SC was supported by the Research Foundation—Flanders (FWO), Grant No. FWOAL938-Junior Research Project. KT was supported by grants from the Science of Learning Institute at Johns Hopkins University and by the NIH/NIDCD through award R01 DC014475 and NIH/NIA through award R01 AG068881.
Publisher Copyright:
© Copyright © 2021 Coemans, Struys, Vandenborre, Wilssens, Engelborghs, Paquier, Tsapkini and Keulen.
PY - 2021/10/7
Y1 - 2021/10/7
N2 - A variety of tDCS approaches has been used to investigate the potential of tDCS to improve language outcomes, or slow down the decay of language competences caused by Primary Progressive Aphasia (PPA). The employed stimulation protocols and study designs in PPA are generally speaking similar to those deployed in post-stroke aphasic populations. These two etiologies of aphasia however differ substantially in their pathophysiology, and for both conditions the optimal stimulation paradigm still needs to be established. A systematic review was done and after applying inclusion and exclusion criteria, 15 articles were analyzed focusing on differences and similarities across studies especially focusing on PPA patient characteristics (age, PPA variant, language background), tDCS stimulation protocols (intensity, frequency, combined therapy, electrode configuration) and study design as recent reviews and group outcomes for individual studies suggest tDCS is an effective tool to improve language outcomes, while methodological approach and patient characteristics are mentioned as moderators that may influence treatment effects. We found that studies of tDCS in PPA have clinical and methodological and heterogeneity regarding patient populations, stimulation protocols and study design. While positive group results are usually found irrespective of these differences, the magnitude, duration and generalization of these outcomes differ when comparing stimulation locations, and when results are stratified according to the clinical variant of PPA. We interpret the results of included studies in light of patient characteristics and methodological decisions. Further, we highlight the role neuroimaging can play in study protocols and interpreting results and make recommendations for future work.
AB - A variety of tDCS approaches has been used to investigate the potential of tDCS to improve language outcomes, or slow down the decay of language competences caused by Primary Progressive Aphasia (PPA). The employed stimulation protocols and study designs in PPA are generally speaking similar to those deployed in post-stroke aphasic populations. These two etiologies of aphasia however differ substantially in their pathophysiology, and for both conditions the optimal stimulation paradigm still needs to be established. A systematic review was done and after applying inclusion and exclusion criteria, 15 articles were analyzed focusing on differences and similarities across studies especially focusing on PPA patient characteristics (age, PPA variant, language background), tDCS stimulation protocols (intensity, frequency, combined therapy, electrode configuration) and study design as recent reviews and group outcomes for individual studies suggest tDCS is an effective tool to improve language outcomes, while methodological approach and patient characteristics are mentioned as moderators that may influence treatment effects. We found that studies of tDCS in PPA have clinical and methodological and heterogeneity regarding patient populations, stimulation protocols and study design. While positive group results are usually found irrespective of these differences, the magnitude, duration and generalization of these outcomes differ when comparing stimulation locations, and when results are stratified according to the clinical variant of PPA. We interpret the results of included studies in light of patient characteristics and methodological decisions. Further, we highlight the role neuroimaging can play in study protocols and interpreting results and make recommendations for future work.
KW - electrode configuration
KW - language rehabilitation
KW - primary progressiva aphasia
KW - speech-and language therapy
KW - stimulation parameters
KW - transcranial direct current stimulation (tDCS)
UR - http://www.scopus.com/inward/record.url?scp=85117937296&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85117937296&partnerID=8YFLogxK
U2 - 10.3389/fnagi.2021.710818
DO - 10.3389/fnagi.2021.710818
M3 - Review article
C2 - 34690737
AN - SCOPUS:85117937296
SN - 1663-4365
VL - 13
JO - Frontiers in Aging Neuroscience
JF - Frontiers in Aging Neuroscience
M1 - 710818
ER -