The purpose of this meta-analysis was to evaluate the therapeutic effect of transcranial direct current stimulation (tDCS) on mild to moderate Alzheimer disease (AD) patients.
PubMed, Embase, Web of Science, and Cochrane Library were searched until April 2018. The primary cognitive outcomes were extracted from included articles. A crude standardized mean difference with 95% CI was calculated by using fixed or random effect models.
Seven studies with 146 patients were included in this meta-analysis. The pooled result showed that tDCS significantly improved cognitive function of AD patients (standardized mean difference=0.37; 95% CI, 0.09-0.65; P=0.01). Subgroup analyses showed that: a single session of tDCS was significantly effective (P<0.05) whereas repeated sessions of tDCS was not lower current density (0.06 mA/cm2) (P>0.05) but not higher current density (0.08 mA/cm2) significantly improved cognitive performance; stimulating the temporal cortex (P<0.05) but not the left dorsal lateral prefrontal cortex significantly improved cognitive function of AD patients; and improved cognitive function occurred in the group with higher education (P<0.05) but not in the group with lower education.
Current evidence suggests that tDCS has a beneficial effect in mild to moderate AD patients. We must be cautious about the results of subgroup analysis given small sample sizes, and further well-designed studies with larger sample size are required to verify these results.
*Department of Radiology & Imaging Institute of Rehabilitation and Development of Brain Function, The Second Clinical Medical College of North Sichuan Medical College Nanchong Central Hospital, Nanchong
‡The Clinical Medical College of Southwest Medical University, Luzhou
¶Peking University Third Hospital, Beijing, China
†Lotus Biotech.com LLC., John Hopkins University-MCC, Rockville, MD
§Department of Genitourinary, University of Texas MD Anderson Cancer Center, Houston, TX
∥Department of Psychiatry, Harvard Medical School, Belmont, CA
The authors declare no conflicts of interest.
Reprints: Qiwen Mu, MD, PhD, Department of Radiology & Imaging Institute of Rehabilitation and Development of Brain Function, The Second Clinical Medical College of North Sichuan Medical College Nanchong Central Hospital, NO. 97 South Renmin Road, Shunqing District, Nanchong 637000, Sichuan, China (e-mail: firstname.lastname@example.org).
Received July 10, 2018
Accepted February 24, 2019