Alpha-tACS improves Neuropsychological Measures in Dementia with Lewy Bodies: a randomized, sham-controlled, double-blind study

Background. Dementia with Lewy bodies (DLB) is a complex neurodegenerative disorder characterized by cognitive, motor, and neuropsychiatric symptoms. These features are driven by a slowing of posterior EEG activity from the alpha toward the pre-alpha/theta band, related to the degeneration of cholinergic projections to the parieto-occipital cortex. The underlying α-synucleinopathy increases patients’ vulnerability to adverse effects from pharmacological treatments, highlighting the need for novel therapeutic options. Transcranial alternating current stimulation (tACS) has emerged as a non-invasive neuromodulation technique capable of entraining cortical oscillations, directly targeting disrupted oscillatory dynamics. Objective. This double-blind, sham-controlled clinical trial aimed to evaluate the safety, feasibility, and cognitive effects of alpha-frequency tACS in individuals diagnosed with DLB. Methods. 10 patients completed the two-week intervention, randomized to receive either the active (n = 6) or the sham protocol (n = 4). Participants underwent 10 sessions lasting 60 minutes each. In the active condition, alternating current at 12 Hz was delivered over the occipital cortex (Oz). In the sham condition, current was delivered for only 30 seconds at the start and at the end of the session. Cognitive performance was assessed at baseline (T0) and after the intervention (T1) with a comprehensive neuropsychological battery. Results. The protocol demonstrated good tolerability and effective blinding. Analysis revealed a selective improvement in visuospatial abilities and visual attention, assessed with the Pentagon Copy (p = .024), and the Visual Search TARGET score (p = .002) and MISSING score (p = .013). Conclusion. Repeated sessions of occipital alpha-tACS appear to be a safe and feasible intervention for patients with DLB, supporting visuospatial processes through the modulation of posterior cortical oscillations.