Dual improvement of cognitive function and auditory ability in elderly patients with hearing impairment by transcranial direct current stimulation-assisted auditory rehabilitation training

To analyze the dual improvement effects of transcranial direct current stimulation (tDCS)-assisted auditory rehabilitation training on cognitive function and auditory ability of elderly patients with hearing impairment. 100 cases of elderly patients with hearing impairment admitted to our hospital between January 2020 and January 2025 were prospectively selected as study subjects. The patients were divided into sham tDCS group (N = 50) and tDCS group (N = 50) according to the randomized numeric table method. All patients received conventional auditory rehabilitation training, and were intervened for 1 month, 3 times/week, 1 h each time. tDCS was given to patients in both groups before conventional auditory rehabilitation training, patients in the tDCS group underwent dual-site sequential high-definition tDCS stimulation, and patients in the sham tDCS group used sham dual-site sequential high definition tDCS stimulation. The main clinical assessments included hearing thresholds, Hearing Handicap Inventory for the Elderly-Screening (HHIE-S), Montreal Cognitive Assessment Scale (MoCA) and Mini-Mental State Examination (MMSE), Communication Performance Assessment (CPA), Personal Report of Communication Apprehension (PRCA-24), and 36-item Short-Form Health Survey (SF-36) scores of the patients in the two groups before and after the treatment. The correlation between hearing threshold, HHIE-S and MoCA and MMSE scores were analyzed by Pearson correlation coefficient. There were no significant differences between the two groups in terms of age, gender, BMI, degree of hearing loss, education level, smoking and drinking habits, laboratory indicators [FBG, ALP, ALT, AST, TC, TG, HDL-C, LDL-C], comorbidities, and family history of hearing loss (all p > 0.05). The hearing thresholds and HHIE-S scores of patients in both groups after treatment were significantly lower than those before treatment (both p = 0.001), and the hearing thresholds and HHIE-S scores of patients in the tDCS group after treatment were significantly lower than those in the sham tDCS group (p < 0.001 and p = 0.002, respectively). The MoCA and MMSE scores of patients in both groups were significantly higher than those before treatment (both p < 0.001), and the MoCA and MMSE scores of patients in the tDCS group were significantly higher than those in the sham tDCS group after treatment (p = 0.048 and p = 0.038, respectively). Hearing thresholds and HHIE-S were negatively correlated with MoCA and MMSE scores in elderly patients with hearing impairment (all p < 0.05). Bootstrap mediation analysis suggests that changes in hearing impairment may partially mediate improvements in cognitive function. After treatment, the total CPA and SF-36 scores of all patients were higher than before treatment, and the total PRCA-24 score was lower than before treatment (p < 0.05). The CPA and SF-36 total scores of the patients in the tDCS group were higher than those in the sham tDCS group after treatment (p = 0.012 and p = 0.007, respectively), and the differences in the PRCA-24 total scores of the two groups were not statistically significant when compared with each other after treatment (p = 0.248). Transcranial direct current stimulation-assisted auditory rehabilitation training may improve the cognitive and auditory functions of elderly patients with hearing impairment and enhance the quality of life of patients.