Neural Noise

tDCS in MCI: white matter and individual response factors

3 min read

  • Mild cognitive impairment (MCI) tDCS trials show variable outcomes, and white matter integrity and individual response factors are key moderators.1
  • Identifying who responds to tDCS and why is a major open problem in the field.1 1

Gardner updates

  • A systematic review with meta-analysis examined tDCS for mild cognitive impairment (MCI) and found that white matter integrity and individual response factors are key moderators. 2

Weekly enrichment (2026-07-20)

  • The most directly relevant primary study (Scientific Reports, 2025) enrolled 55 individuals with MCI and used MRI-based computational modeling to optimize electric-field (EF) strength at the left dorsolateral prefrontal cortex (DLPFC), with diffusion tensor imaging (fractional anisotropy [FA], mean diffusivity [MD], radial diffusivity [RD]) assessing white-matter (WM) integrity after a two-week, 10-session anodal tDCS protocol.3
  • Higher EF strength was significantly associated with increased FA and reduced MD and RD in specific left-lateralized tracts, including the anterior thalamic radiation, corticospinal tract, inferior fronto-occipital fasciculus, and inferior longitudinal fasciculus.3
  • These EF-dependent WM changes were moderated by Alzheimer’s-related factors, with greater plasticity in Aβ-positive individuals, APOE ε4 non-carriers, and BDNF Met non-carriers.3
  • APOE ε4 status moderated the EF–executive-function relationship: in non-carriers, stronger EF was associated with improved Stroop performance (linked to right superior longitudinal fasciculus integrity), yet no EF-sensitive tract predicted short-term cognitive change in the full sample, suggesting structural change may precede functional gains.3
  • An earlier precision-medicine study (Frontiers in Aging Neuroscience, 2023) applied sequential 2 mA/day left-DLPFC tDCS for 10 sessions in 63 MCI patients and found APOE ε4 status and sex interacted with tDCS to raise FA in the right uncinate fasciculus, while baseline Aβ deposition correlated with left-cingulum FA change and delayed-memory improvement.4
  • On clinical efficacy, a 109-subject multicentre randomized active-controlled trial combining anodal tDCS with virtual-reality cognitive rehabilitation found long-lasting episodic-memory improvement only in the active-tDCS arm (p < 0.001), not the sham-tDCS or treatment-as-usual arms.5
  • Illustrating the field’s underpowering, several MCI tDCS RCTs remain small (e.g., n = 35 amnestic MCI over the left DLPFC; n = 41 in a home-delivered MCI-AD trial powered for medium effects), which limits detection of individual response moderators.67
  • BCI/clinical implication: the evidence supports biomarker-informed, individually dosed (EF-optimized) tDCS over fixed protocols, and nominates WM integrity plus APOE, BDNF, and Aβ status as candidate response predictors — directly addressing the “who responds and why” problem.34

Footnotes

  1. https://news.google.com/rss/articles/CBMivgFBVV95cUxNbmNSWlZJb0lCUTFIdVFaSXJqTW9HbmtrSnZ0a1RGNjk1WUpwUGJVWTlJZVFROUt1R3o1b2VOM3E1WnFwemxBY3hCWjFPOXNOT1BiaVJhUGpINW1qeUh0UWRxZm1ldEh4TjlBSWtnVVJfMUxnc2VRek1FcWRkMG14bTVsQTdYU0owX2FPeGh6TFE0NUtxc2pQN0h5c3dGSFNnSDVlUTRQVHFDUkJidU9fNjRJckhiTEhJUE5oMndreE5CNA?oc=5 ↩ ↩2 ↩3

  2. https://news.google.com/rss/articles/CBMivgFBVV95cUxNOVFUS01VbW1KUFdNbm9DWEFOMXR5WExJcWVkQ2dfMVFxSHFZMllQdEhWSHpkUEVUX1FkMFpxR0VkV3J4TmFiOUxGb21sbm0xMHV3SmkybVVmbXJseF92MzdXWDZNb1h3cjMtYlB3WGVKWG5zSTVuNXd0elpFbFN2ZTlZdjFVZlIwT1J2ZUZiZ1AzUi1Vb2pxd2FCWFVFSDJxTk4xR25ReDZTM2RGZHhHSmNraDBBWVdKVFJEb1ZoRGhXdA?oc=5 ↩

  3. https://doi.org/10.1038/s41598-025-27612-7 ↩ ↩2 ↩3 ↩4 ↩5

  4. https://doi.org/10.3389/fnagi.2023.1234086 ↩ ↩2

  5. https://www.frontiersin.org/journals/aging-neuroscience/articles/10.3389/fnagi.2024.1414593/full ↩

  6. https://www.nature.com/articles/s41598-024-51690-8 ↩

  7. https://link.springer.com/article/10.1186/s12877-026-07481-z ↩

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