There have been increasing efforts to investigate the effects of neuromodulation techniques, such as transcranial direct current stimulation (tDCS), on cognitive impairment in dementia and related conditions. In this systematic review and meta-analysis, we assessed the efficacy of multisession anodal tDCS compared with sham stimulation for improving global cognition and specific cognitive domains in both Alzheimer's disease and mild cognitive impairment. Eight articles meeting the criteria for inclusion in the meta-analysis were selected. Five studies used the Mini-Mental State Examination to examine mild cognitive impairment and dementia. In a fixed-effect model, there was a mean difference in the change score of -0.13 points. Three trials for dementia using the Alzheimer's Disease Assessment Scale-Cognition showed a mean difference of -0.53 points. At present, there is a lack of clear evidence concerning the efficacy of multisession anodal tDCS due to the small number of studies and different measures used. This underscores the need for further investigations using larger samples and common outcome measures.
Transcranial direct current stimulation, one of the neuromodulation paradigms, is attracting interest as a novel method to treat various central nervous system disorders. It is safe, portable, and cost-effective, and has been applied experimentally for patients with various neuropsychiatric conditions. For the clinical importance and preliminary positive results, growing number of randomized controlled trials to patients with depression or schizophrenia are reported, followed by systematic reviews and meta-analyses. However, former research specifically focuses on depression or psychosis in psychiatric disorders. Therefore, we provide a systematic review of studies reporting the effectiveness of transcranial direct current stimulation in ameliorating these symptoms not limited to psychiatric patients or objective scales by examining double-blind sham-controlled trials.
Recent research on neuromodulation techniques, such as transcranial direct current stimulation (tDCS), for the treatment of schizophrenia has mainly focused on psychotic symptoms. We aimed to determine whether repetitive tDCS is efficacious in improving determinants of outcome, such as cognitive function, daily living skills, and depressive mood in patients with schizophrenia. Twenty-eight patients underwent tDCS (2 mA × 20 min) two times per day for 5 consecutive days. The anodal electrode was placed over the left dorsolateral prefrontal cortex while the cathodal electrode was placed over the right supraorbital region. One month after the last stimulation, there was a significant improvement on cognitive function, measured by the brief assessment of cognition in schizophrenia (d = 0.49). Significant effects were also shown on daily living skills (functional capacity), measured by the UCSD performance-based skills assessment-brief (d = 0.70). Depressive symptoms, measured by the Calgary depression rating scale, as well as psychotic symptoms measured by on the positive and negative syndrome scale positive and general psychopathology subscales also responded to the treatment (d = 0.38, d = 0.48, and d = 0.50, respectively). This is the first study to suggest that tDCS with the anodal electrode on the left prefrontal cortex improves functional capacity and depressive symptoms in patients with schizophrenia. These results may add to the concept that tDCS provides a strategy to enhance functional outcomes in patients with schizophrenia.Trial Registration, UMIN000015953.
Major mental illnesses such as schizophrenia (SZ) and bipolar disorder (BP) frequently accompany metabolic conditions, but their relationship is still unclear, in particular at the Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:
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