Transcranial direct current stimulation improves recognition memory in Alzheimer disease

TLDR

The study evaluated the cognitive effect of temporoparietal transcranial direct current stimulation (tDCS) in patients with Alzheimer disease. In 10 probable AD patients, anodal, cathodal, and sham tDCS were delivered over temporoparietal areas in three sessions, with recognition memory and visual attention assessed at baseline and 30 minutes post‑stimulation. Anodal tDCS increased word‑recognition accuracy (15.5 → 17.9), cathodal tDCS decreased it (15.8 → 13.2), and sham had no effect, while visual attention remained unchanged, indicating tDCS specifically enhances recognition memory in AD.

Abstract

<b>Objective: </b> To evaluate the cognitive effect of transcranial direct current stimulation (tDCS) over the temporoparietal areas in patients with Alzheimer disease (AD). <b>Methods: </b> In 10 patients with probable AD, we delivered anodal tDCS (AtDCS), cathodal tDCS (CtDCS), and sham tDCS (StDCS) over the temporoparietal areas in three sessions. In each session recognition memory and visual attention were tested at baseline (prestimulation) and 30 minutes after tDCS ended (poststimulation). <b>Results: </b> After AtDCS, accuracy of the word recognition memory task increased (prestimulation: 15.5 ± 0.9, poststimulation: 17.9 ± 0.8, <i>p</i> = 0.0068) whereas after CtDCS it decreased (15.8 ± 0.6 vs 13.2 ± 0.9, <i>p</i> = 0.011) and after StDCS it remained unchanged (16.3 ± 0.7 vs 16.0 ± 1.0, <i>p</i> = 0.75). tDCS left the visual attention-reaction times unchanged. <b>Conclusion: </b> Transcranial direct current stimulation (tDCS) delivered over the temporoparietal areas can specifically affect a recognition memory performance in patients with Alzheimer disease (AD). Because tDCS is simple, safe and inexpensive, our finding prompts studies using repeated tDCS, in conjunction with other therapeutic interventions for treating patients with AD.