Repetitive transcranial magnetic stimulation combined with Tai Chi improves working memory in older adults with sleep disorders and mild cognitive impairment: An fMRI-based randomized controlled trial

Background Working memory impairment has been reported in older adults with sleep disorders and MCI, with the frontoparietal network playing a central role in working memory. The key question is whether integrating Tai Chi with rTMS improves working memory, and whether such improvements result from the modulation of frontoparietal networks plasticity. Methods Seventy-one participants with sleep disorders and MCI were assigned to the experimental group (Tai Chi + 1-Hz rTMS, n = 37) or sham group (Tai Chi + sham rTMS, n = 34). They completed 6 weeks of Tai Chi combined with neuronavigated rTMS targeted the right DLPFC and underwent fMRI scans. Outcomes included Numerical N-back task, digit span task，Pittsburgh Sleep Quality Index (PSQI), Montreal Cognitive Assessment (MoCA). Task fMRI measured N-back activation patterns, and seed-based resting-state functional connectivity (rsFC) was assessed. Correlations between the activation/rsFC and N-back task performance were explored. Results Seventy-one participants (mean age 67.6 ± 4.6 years; 30 male [42%], 41 female [58%]) were included. After 6 weeks, the experimental group showed significant improvements versus shams in PSQI, MoCA, 0-back and 2-back task accuracy, 0-back reaction time, and forward digit span (all p < 0.05). The 2-back accuracy was negatively correlated with right precuneus activation (r = -0.381, p = 0.034) and positively correlated with right precuneus connectivity to the left SMA (r = 0.367, p = 0.042). Conclusion Adjunctive neuronavigated rTMS delivered in addition to Tai Chi training may enhance working memory rehabilitation in older adults with sleep disorders and MCI, with frontoparietal network modulation as a potential neural basis. Trial registration Clinical trial registration no. ChiCTR 2200063274.