RESUMEN
BACKGROUND: Dementia with Lewy bodies (DLB) is characterized by a marked shift of electroencephalographic (EEG) power and dominant rhythm, from the α toward the θ frequency range. Transcranial alternate current stimulation (tACS) is a non-invasive brain stimulation technique that allows entrainment of cerebral oscillations at desired frequencies. OBJECTIVES: Our goal is to evaluate the effects of occipital α-tACS on cognitive functions and neurophysiological measures in patients with DLB. METHODS: We conducted a double-blind, randomized, sham-controlled, cross-over clinical trial in 14 participants with DLB. Participants were randomized to receive either α-tACS (60 minutes of 3 mA peak-to-peak stimulation at 12 Hz) or sham stimulation applied over the occipital cortex. Clinical evaluations were performed to assess visuospatial and executive functions, as well as verbal episodic memory. Neurophysiological assessments and EEG recordings were conducted at baseline and following both α-tACS and sham stimulations. RESULTS: Occipital α-tACS was safe and well-tolerated. We observed a significant enhancement in visuospatial abilities and executive functions, but no improvement in verbal episodic memory. We observed an increase in short latency afferent inhibition, a neurophysiological marker indirectly and partially dependent on cholinergic transmission, coinciding with an increase in α power and a decrease in Δ power following α-tACS stimulation, effects not seen with sham stimulation. CONCLUSIONS: This study demonstrates that occipital α-tACS is safe and enhances visuospatial and executive functions in patients with DLB. Improvements in indirect markers of cholinergic transmission and EEG changes indicate significant neurophysiological engagement. These findings justify further exploration of α-tACS as a therapeutic option for DLB patients. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
RESUMEN
BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the possible correlation between SARS-CoV-2 vaccines and the onset of neurological syndromes. The aim was to challenge the association between SARS-CoV-2 vaccinations and the onset of acute functional neurological disorders (FNDs) compared to other neurological syndromes in hospitalized patients. METHODS: In this prospective cohort study, all adult inpatients consecutively admitted to a tertiary neurological centre were included. The prevalence and characteristics of neurological syndromes were compared between unvaccinated and vaccinated cases stratified according to the onset from vaccination. The study involved 843 subjects, namely 411 unvaccinated (UVC) and 432 vaccinated cases; these groups were comparable for demographics and clinical diagnosis distribution. RESULTS: Compared to UVC, subjects hospitalized within the first 30 days from vaccine exhibited higher prevalence of FNDs (12.3% vs. 3.6%; odds ratio 4.2, 95% confidence interval 1.6-11.1) and headache (10.8% vs. 5%; odds ratio 4.1, 95% confidence interval 1.9-8.8) but no other neurological syndromes. The FND cases following vaccinations showed similar premorbid conditions and severity but a higher percentage of sensory symptoms and pain compared to UVC FND cases. CONCLUSIONS: SARS-CoV-2 vaccination is associated with a significant short-term increased risk of FND and headache requiring hospitalization in an acute neurological setting.