Combination of Vestibular Rehabilitation and Galvanic VestibularStimulation ImprovesVerbal andVisuospatial Memory: A Randomized Control Trial in Patients with Amnestic Mild Cognitive Impairment

Background and Aim: Considering the critical input of the vestibular system to the hippocampus as an area involved in cognition, and vestibular disorders reported in patients with amnestic Mild Cognitive Impairment (aMCI), we aimed to investigate the effects of Vestibular Rehabilitation (VR) with and without noisy Galvanic Vestibular Stimulation (nGVS) on cognitive function in patients with aMCI. Methods: In a randomized controlled trial, twenty-two patients with aMCI were randomly assigned to two groups receiving: 1) VR for four weeks (VR group); 2) VR for four weeks with nGVS for three sessions (GVS+VR group). Outcome measures were Rey's Auditory-Verbal Learning Test (RAVLT), Corsi blocks, Visual Search (VS), and match to sample tests. Results: Mean immediate and delayed recalls of RAVLT, all of the outcomes of Corsi blocks and VS tests, and the error rate of the match to sample tests improved significantly after intervention in VR and GVS+VR groups. Between-group differences were observed for learning and delayed recalls of RAVLT (p=0.001, d=0.444 and p<0.001, d=0.512 respectively), reaction times 1 and 2 in VS (p=0.007, d=0.325 and p=0.001, d=0.446 respectively), the total correct trial of Corsi blocks (p=0.026, d=0.235), and error rate of the match to sample (p=0.017, d=0.266) tests. Conclusion: The synergistic effect of VR and GVS suggested that simultaneous use of both stimulations improves verbal and visuospatial memory in aMCI patients. Study protocol location: https://irct.ir/trial/47249 Trial registration number: IRCT20160131026279N3 Keywords: Mild cognitive impairment; spatial memory; verbal memory; hippocampus; galvanic vestibular stimulation; vestibular rehabilitation