Efficacy of transcranial direct current stimulation in mild cognitive impairment – a meta‐analysis

Abstract

AbstractBackgroundMCI or Mild Cognitive Impairment is a state of cognitive decline which is in between that of normal ageing and dementia. People with MCI have a higher chance of progressing to dementia because of which introducing interventions at this stage becomes increasingly important. Transcranial Direct Current Stimulation (tDCS) is one non‐invasive brain stimulation technique that is considered as an effective intervention strategy for people with MCI to prevent their progression to dementia.MethodFrom 221 and 686 results obtained from PubMed and Google Scholar respectively using the search term ‘(“tDCS”) AND (“MCI”) AND (Randomized) AND (sham controlled)’, 8 studies were included for the current meta‐analysis. Among these studies, the most commonly used cognitive tests namely MMSE (Mini Mental State Examination), MoCA (Montreal Cognitive Assessment), TMT (Trail Making Test) A and B, DST (Digit Span Test) forward and backward and Logical Memory Test were considered for the analysis. The standard mean difference between active and sham treatments in different tests were computed.ResultThe standard mean difference and the 95% confidence interval for the test scores are MoCA: 0.37 (‐0.22,0.95), MMSE: 0.26 (‐0.25, 0.77), TMT A: ‐0.01 (‐0.42, 0.40), TMT B: 0.07 (‐0.41, 0.55), DST F: ‐0.09 (‐0.44, 0.25), DST B: ‐0.11 (‐0.54, 0.31) and Logical memory test: 0.80 (‐0.24, 1.83). It is found that there is an improvement in the performance in MoCA, MMSE, TMT A and logical memory test after treatment with active tDCS but the improvement is statistically insignificant.ConclusionAlthough there is an evident clinical effectiveness, the study identified no significant improvement in cognitive performance with active tDCS in comparison with sham tDCS. This might be due to difference in protocols followed among studies, lower duration of stimulation in a few studies and smaller sample size in each.