Effects of multisite anodal transcranial direct current stimulation combined with cognitive stimulation in patients with Alzheimer's disease and its neurophysiological correlates: A double-blind randomized clinical trial

Objectives: We aimed to examine the effects of multisite anodal transcranial direct current stimulation (tDCS) combined with cognitive stimulation (CS) over 2 months on cognitive performance and brain activity, and the relationship between them, in patients with Alzheimer's disease (AD). Methods: Patients with AD were randomly assigned to an active tDCS+CS (n=18) or a sham tDCS +CS (n=18) group. Cognitive performance was assessed using the Alzheimer Disease Assessment Scale-cognitive subscale (ADAS-cog) and brain activity using EEG (spectral power and coherence analysis) before and after the intervention. Multisite anodal tDCS (2 mA, 30 min) was applied over six brain regions [left and right dorsolateral prefrontal cortex (F3 and F4), Broca's area (F5), Wernicke's area (CP5), left and right somatosensory association cortex (P3 and P4)] for 24 sessions (three times a week). Both groups performed CS during tDCS. Results: Anodal tDCS+CS delays cognitive decline (ADAS-cog change) to a greater extent than sham tDCS+CS (-3.4 +/- 1.1 vs. -1.7 +/- 0.4; p=.03). Bilateral EEG coherence at high and low frequencies was greater for the active tDCS+CS than sham+CS group for most electrode pairs assessed (p <.05). The post-intervention ADAS-cog change score was predictive for EEG coherence at different sites (R-2=.59 to.68; p <.05) in the active but not in the sham tDCS+CS group. Conclusion: Anodal tDCS+CS improved overall cognitive function and changed EEG brain activity compared to sham tDCS+CS. Changes in cognitive performance were associated with changes in EEG measures of brain activity. Anodal tDCS+CS appears to be a promising therapeutic strategy to modulate cortical activity and improve cognitive function in patients with AD. (C) 2022 Elsevier Masson SAS. All rights reserved.

Automated summary

The study found that multisite anodal transcranial direct current stimulation combined with cognitive stimulation can improve cognitive function and brain activity in patients with Alzheimer's disease, and the changes in cognitive performance are associated with changes in brain activity.