Cognitive Effect of Transcranial Direct Current Stimulation on Left Dorsolateral Prefrontal Cortex in Mild Alzheimer’s Disease: A Randomized, Double-Blind, Cross-Over Small-Scale Exploratory Study

Article type: Research Article

Authors: Wang, Carol Sheei-Meei^{a; b; c; *} | Chen, Po See^{c; d} | Tsai, Tsung-Yu^c | Hou, Nien-Tsen^e | Tang, Chia-Hung^b | Chen, Pai-Lien^f | Huang, Ying-Che^e | Cheng, Kuo-Sheng^{a; *}

Affiliations: [a] Department of BioMedical Engineering, National Cheng Kung University, Tainan City, Taiwan | [b] Department of Psychiatry, Tainan Hospital, Ministry of Health and Welfare, Tainan City, Taiwan | [c] Department of Psychiatry, College of Medicines, National Cheng Kung University Hospital, National Cheng Kung University, Tainan City, Taiwan | [d] Institute of Behavioral Medicine, College of Medicine, National Cheng Kung University, Tainan City, Taiwan | [e] Department of Neurology, Tainan Hospital, Ministry of Health and Welfare, Tainan City, Taiwan | [f] Biostatistics Department, Family Health International (FHI) 360, Durham, NC, USA

Correspondence: [*] Correspondence to: Kuo-Sheng Cheng, PhD, and Carol Sheei-Meei Wang, Department of BioMedical Engineering, National Cheng Kung University, No.1 University Road, Tainan City 701, Taiwan (R.O.C.). Tel.: +886 6 2757575 63424/886 9 88661616; Fax: +886 6 2343270; E-mails:kscheng@mail.ncku.edu.tw (Kuo-Sheng Cheng) and sheeicarol@gmail.com (Carol Sheei-Meei Wang).

Abstract: Background:Transcranial direct current stimulation (tDCS) is considered a potential therapeutic instrument for Alzheimer’s disease (AD) because it affects long-term synaptic plasticity through the processes of long-term potentiation and long-term depression, thereby improving cognitive ability. Nevertheless, the efficacy of tDCS in treating AD is still debated. Dorsal lateral prefrontal cortex is the main role in executive functions. Objective:We investigate the cognitive effects of tDCS on AD patients. Methods:Thirty mild AD patients aged 66–86 years (mean = 75.6) were included in a double-blind, randomized, sham-controlled crossover study. They were randomly assigned to receive 10 consecutive daily sessions of active tDCS (2 mA for 30 min) or a sham intervention and switched conditions 3 months later. The anodal and cathodal electrodes were placed on the left dorsal lateral prefrontal cortex and the right supraorbital area, respectively. Subjects underwent various neuropsychological assessments before and after the interventions. Results:The results showed that tDCS significantly improved Cognitive Abilities Screening Instrument scores, especially on the items of “concentration and calculation”, “orientation”, “language ability”, and “categorical verbal fluency”. Mini-Mental State Examination and Wisconsin Card Sorting Test scores in all domains of “concept formation”, “abstract thinking”, “cognitive flexibility”, and “accuracy” also improved significantly after tDCS. For the sham condition, no difference was found between the baseline scores and the after-intervention scores on any of the neuropsychological tests. Conclusion:>: Using tDCS improves the cognition of AD patients. Further large size clinical trials are necessary to validate the data.

Keywords: Alzheimer’s disease, cognitive function, effect, left dorsal lateral prefrontal cortex, transcranial direct currentstimulation

DOI: 10.3233/JAD-240002

Journal: Journal of Alzheimer's Disease, vol. 98, no. 2, pp. 563-577, 2024