Effect of Tai Chi and transcranial direct current stimulation on spontaneous neural activity in patients with mild cognitive impairment: An exploratory resting-state fMRI study

INTRODUCTION: Tai Chi (TC) combined with transcranial direct current stimulation (tDCS) improves memory function in patients with mild cognitive impairment (MCI), but underlying neurophysiological mechanisms remain unclear. This study aims to explore whether TC and tDCS can independently or interactively regulate spontaneous neural activity in different brain regions and enhance memory function. METHODS: In a randomized 2 × 2 factorial trial, 128 MCI patients were assigned to TC, tDCS, TC combined with tDCS, or health education for 12 weeks. Memory performance was assessed using the Chinese Wechsler Memory Scale-Revised (WMS-RC), Auditory Verbal Learning Test (AVLT), and Rey-Osterrieth Complex Figure Test (ROCF). Resting-state functional MRI was performed at baseline and post-intervention. RESULTS: TC significantly improved WMS-RC memory quotient (P < 0.001), AVLT-cued recall (P = 0.042), recognition (P = 0.005), and increased activity in the middle/inferior temporal gyrus (P < 0.05). tDCS significantly enhanced memory quotient (P < 0.001), ROCF-recall (P = 0.030), AVLT-recognition (P = 0.013), and modulated activity in the left postcentral gyrus, lingual gyrus, calcarine fissure, and bilateral frontal regions (P < 0.05). TC combined with tDCS significantly interacted with immediate recall (P = 0.016) and altered activity across multiple cortical regions (P < 0.05), and changes in immediate recall were negatively correlated with the ALFF value of the right orbital part of the middle frontal gyrus (r = -0.263, P = 0.011). CONCLUSIONS: TC and tDCS have distinct yet complementary neural and cognitive effects in MCI, supporting their integration as a promising multimodal strategy to delay cognitive decline. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2200059316.