Transcranial direct current stimulation (tDCS) in elderly with mild cognitive impairment: A pilot study

Transcranial direct current stimulation (tDCS) is a non-invasive, painless and easy-to use-technology. It can be used in depression, schizophrenia and other neurological disorders. There are no studies about longer usage protocols regarding the ideal duration and weekly frequency of tDCS. OBJECTIVE: to study the use of tDCS twice a week for longer periods to improve memory in elderly with MCI. METHODS: a randomized double-blind controlled trial of anodal tDCS on cognition of 58 elderly aged over 60 years was conducted. A current of 2.0 mA was applied for 30 minutes for 10 sessions, twice a week. The anode was placed over the left dorsolateral prefrontal cortex (LDLFC). Subjects were evaluated before and after 10 sessions by the following tests: CAMCOG, Mini-Mental State Examination (MMSE), Trail Making, Semantic Verbal Fluency (Animals), Boston naming, Clock Drawing Test, Word list memory (WLMT), Direct and Indirect Digit Order (WAIS-III and WMS-III) and N-back. RESULTS: After 10 sessions of tDCS, significant group-time interactions were found for the CAMCOG - executive functioning (χ(2) = 3.961, p = 0.047), CAMCOG - verbal fluency (χ(2) = 3.869, p = 0.049), CAMCOG - Memory recall (χ(2) = 9.749, p = 0.004), and WMLT - recall (χ(2) = 7.254, p = 0.007). A decline in performance on the CAMCOG - constructional praxis (χ(2) = 4.371, p = 0.037) was found in the tDCS group after intervention. No significant differences were observed between the tDCS and Sham groups for any other tasks. CONCLUSION: tDCS at 2 mA for 30 min twice a week over 5 consecutive weeks proved superior to placebo (Sham) for improving memory recall, verbal fluency and executive functioning in elderly with MCI.