The effects of transcranial direct current stimulation on global cognition in patients with Alzheimer's disease: An update meta-analysis

Background Alzheimer's disease (AD) is a neurodegenerative disease. At present, there are currently no drugs that can cure AD. Objective A number of empirical studies have shown that transcranial direct current stimulation (tDCS) may be used to treat cognitive abnormalities in patients with AD. We will through meta-analysis reviews tDCS overall research on the effects of cognitive function in patients with AD. Methods Systematic searches were performed in the PubMed, Embase, and Cochrane Library databases from their creation until 8 March 2024. Using a fixed effect model and random effect model to evaluate the average difference between the treatment group and control group (MD) and its 95% confidence interval (CI). Results The study included 10 randomized controlled trials (Nactive = 165, Nsham = 167). The results of the overall analysis showed that tDCS did not significantly improve the overall cognitive function (SMD = 0.17; 95%CI = −0.05, 0.39; p = 0.14; I² = 51%). Quality of life of AD patients after treatment was also evaluated, but no improvement was seen. Subgroup analysis showed no significant improvement in global cognitive function after tDCS treatment. The sensitivity analysis to confirm the reliability of the data, risk assessment did not find any high-risk projects. Conclusions The tDCS treatment did not improve cognitive function in patients with AD. Further empirical research in the future will help to explore new schemes for tDCS to improve cognitive function of patients.