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.

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.

Montreal Cognitive Assessment and Mini-Mental State Examination performance in patients with mild-to-moderate dementia with Lewy bodies, Alzheimer's disease, and normal participants in Taiwan.

BACKGROUND: The aim of this study was to examine and test the sensitivity, specificity, and threshold scores of the Montreal Cognitive Assessment (MoCA) and the Mini-Mental State Examination (MMSE) and determine those that best correspond to a clinical diagnosis of dementia with Lewy bodies (DLB). METHODS: Sixty-seven Alzheimer's disease (AD), 36 DLB, and 62 healthy participants without dementia (NC), aged 60 to 90, were enrolled. All three groups took the MoCA and MMSE tests at the same time. The Cochran-Mantel-Haenszel tests and receiver operating characteristics curve analysis were used to compare the different neuropsychological test results among the groups. RESULTS: The cut-off point of the MoCA for AD was 21/22 with a sensitivity of 95.5% and a specificity of 82.3% (area under the curve (AUC): 0.945), and the cut-off point for DLB was 22/23 with a sensitivity of 91.7% and a specificity of 80.6% (AUC: 0.932). For the MMSE, the cut-off points for AD and for DLB from NC were all 24/25, with a sensitivity of 88.1% and a specificity of 85.5% for AD (AUC: 0.92), and a sensitivity of 77.8% and a specificity of 85.5% for DLB (AUC: 0.895). After controlling sex, age, and education, AD and DLB had lower scores in all MoCA subscales than the NC group (p < 0.05), except for the orientation and naming in DLB. In addition, AD had a lower score in the MoCA orientation (p = 0.03) and short-term memory (p = 0.02) than did DLB. CONCLUSIONS: The MoCA is a more sensitive instrument than the MMSE to screen AD or DLB patients from non-dementia cases.