Inter-Individual Variability in tDCS Effects: A Narrative Review on the Contribution of Stable, Variable, and Contextual Factors
Due to its safety, portability, and cheapness, transcranial direct current stimulation (tDCS) use largely increased in research and clinical settings. Despite tDCS’s wide application, previous works pointed out inconsistent and low replicable results, sometimes leading to extreme conclusions about t...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-04-01
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| Series: | Brain Sciences |
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| Online Access: | https://www.mdpi.com/2076-3425/12/5/522 |
| _version_ | 1797501186732982272 |
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| author | Alessandra Vergallito Sarah Feroldi Alberto Pisoni Leonor J. Romero Lauro |
| author_facet | Alessandra Vergallito Sarah Feroldi Alberto Pisoni Leonor J. Romero Lauro |
| author_sort | Alessandra Vergallito |
| collection | DOAJ |
| description | Due to its safety, portability, and cheapness, transcranial direct current stimulation (tDCS) use largely increased in research and clinical settings. Despite tDCS’s wide application, previous works pointed out inconsistent and low replicable results, sometimes leading to extreme conclusions about tDCS’s ineffectiveness in modulating behavioral performance across cognitive domains. Traditionally, this variability has been linked to significant differences in the stimulation protocols across studies, including stimulation parameters, target regions, and electrodes montage. Here, we reviewed and discussed evidence of heterogeneity emerging at the intra-study level, namely inter-individual differences that may influence the response to tDCS within each study. This source of variability has been largely neglected by literature, being results mainly analyzed at the group level. Previous research, however, highlighted that only a half—or less—of studies’ participants could be classified as responders, being affected by tDCS in the expected direction. Stable and variable inter-individual differences, such as morphological and genetic features vs. hormonal/exogenous substance consumption, partially account for this heterogeneity. Moreover, variability comes from experiments’ contextual elements, such as participants’ engagement/baseline capacity and individual task difficulty. We concluded that increasing knowledge on inter-dividual differences rather than undermining tDCS effectiveness could enhance protocols’ efficiency and reproducibility. |
| first_indexed | 2024-03-10T03:14:45Z |
| format | Article |
| id | doaj.art-934dc6884ba3491c8d26fd80954dd6b8 |
| institution | Directory Open Access Journal |
| issn | 2076-3425 |
| language | English |
| last_indexed | 2024-03-10T03:14:45Z |
| publishDate | 2022-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Brain Sciences |
| spelling | doaj.art-934dc6884ba3491c8d26fd80954dd6b82023-11-23T10:16:32ZengMDPI AGBrain Sciences2076-34252022-04-0112552210.3390/brainsci12050522Inter-Individual Variability in tDCS Effects: A Narrative Review on the Contribution of Stable, Variable, and Contextual FactorsAlessandra Vergallito0Sarah Feroldi1Alberto Pisoni2Leonor J. Romero Lauro3Department of Psychology & NeuroMi, University of Milano Bicocca, 20126 Milano, ItalySchool of Medicine and Surgery, University of Milano-Bicocca, 20854 Monza, ItalyDepartment of Psychology & NeuroMi, University of Milano Bicocca, 20126 Milano, ItalyDepartment of Psychology & NeuroMi, University of Milano Bicocca, 20126 Milano, ItalyDue to its safety, portability, and cheapness, transcranial direct current stimulation (tDCS) use largely increased in research and clinical settings. Despite tDCS’s wide application, previous works pointed out inconsistent and low replicable results, sometimes leading to extreme conclusions about tDCS’s ineffectiveness in modulating behavioral performance across cognitive domains. Traditionally, this variability has been linked to significant differences in the stimulation protocols across studies, including stimulation parameters, target regions, and electrodes montage. Here, we reviewed and discussed evidence of heterogeneity emerging at the intra-study level, namely inter-individual differences that may influence the response to tDCS within each study. This source of variability has been largely neglected by literature, being results mainly analyzed at the group level. Previous research, however, highlighted that only a half—or less—of studies’ participants could be classified as responders, being affected by tDCS in the expected direction. Stable and variable inter-individual differences, such as morphological and genetic features vs. hormonal/exogenous substance consumption, partially account for this heterogeneity. Moreover, variability comes from experiments’ contextual elements, such as participants’ engagement/baseline capacity and individual task difficulty. We concluded that increasing knowledge on inter-dividual differences rather than undermining tDCS effectiveness could enhance protocols’ efficiency and reproducibility.https://www.mdpi.com/2076-3425/12/5/522tDCSinter-individual differencesinter-subject variabilityreproducibilitynoninvasive brain stimulation |
| spellingShingle | Alessandra Vergallito Sarah Feroldi Alberto Pisoni Leonor J. Romero Lauro Inter-Individual Variability in tDCS Effects: A Narrative Review on the Contribution of Stable, Variable, and Contextual Factors Brain Sciences tDCS inter-individual differences inter-subject variability reproducibility noninvasive brain stimulation |
| title | Inter-Individual Variability in tDCS Effects: A Narrative Review on the Contribution of Stable, Variable, and Contextual Factors |
| title_full | Inter-Individual Variability in tDCS Effects: A Narrative Review on the Contribution of Stable, Variable, and Contextual Factors |
| title_fullStr | Inter-Individual Variability in tDCS Effects: A Narrative Review on the Contribution of Stable, Variable, and Contextual Factors |
| title_full_unstemmed | Inter-Individual Variability in tDCS Effects: A Narrative Review on the Contribution of Stable, Variable, and Contextual Factors |
| title_short | Inter-Individual Variability in tDCS Effects: A Narrative Review on the Contribution of Stable, Variable, and Contextual Factors |
| title_sort | inter individual variability in tdcs effects a narrative review on the contribution of stable variable and contextual factors |
| topic | tDCS inter-individual differences inter-subject variability reproducibility noninvasive brain stimulation |
| url | https://www.mdpi.com/2076-3425/12/5/522 |
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