Effects of transcranial direct current stimulation upon attention and visuoperceptual function in Lewy body dementia: a preliminary study

BACKGROUND: Individuals with Lewy body dementia (LBD) typically exhibit impairments in attentional and executive function. Current pharmacological treatments have limited efficacy, with associated side effects. Transcranial direct current stimulation (tDCS) may represent an alternative treatment, as cognitive improvements have been demonstrated in healthy individuals. However, no studies to date have assessed the feasibility of tDCS in an LBD population. The aim of this preliminary study, therefore, was to assess the tolerability of tDCS, as well as its effects upon attentional and visuoperceptual performance, in LBD patients.

METHODS: Thirteen participants completed attentional (simple reaction time, choice reaction time, and digit vigilance) and forced-choice visuoperceptual (angle and motion perception) tasks before and after one 20-min session of active tDCS (0.08 mA/cm2). The anodal electrode was applied to the left dorsolateral prefrontal cortex and the cathodal electrode was applied to the right deltoid. Attentional (task accuracy and reaction time to correct answers) and visuoperceptual (task accuracy and difficulty) outcome measures were compared using paired t-tests.

RESULTS: All participants tolerated stimulation and did not report any side effects during or immediately after stimulation. Post-stimulation improvements were observed in the choice reaction time (increased percentage of correct answers; p = 0.01) and digit vigilance (reduced mean reaction time to correct answers; p = 0.02) attention tasks. Visuoperceptual task performance did not improve (all p-values > 0.05).

CONCLUSIONS: Attentional, but not visuoperceptual, improvements were observed following stimulation in LBD patients. Larger-scale, placebo-controlled trials are needed to confirm whether tDCS is a useful treatment option for attentional deficits in LBD.