Transcranial direct current stimulation (tDCS) in elderly with mild cognitive impairment: A pilot study / Estimulação Transcraniana por Corrente Direta (ETCD) em idosos com comprometimento cognitivo leve: um estudo piloto

ABSTRACT. 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 (χ2 = 3.961, p = 0.047), CAMCOG - verbal fluency (χ2 = 3.869, p = 0.049), CAMCOG - Memory recall (χ2 = 9.749, p = 0.004), and WMLT - recall (χ2 = 7.254, p = 0.007). A decline in performance on the CAMCOG - constructional praxis (χ2 = 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.

RESUMO. A ETCC (estimulação transcraniana por corrente contínua) é uma tecnologia não-invasiva, indolor e de fácil utilização. Pode ser usada na depressão, esquizofrenia e outros distúrbios neurológicos. Não há orientações ideais sobre o uso de protocolos mais longos quanto à duração e frequência semanal da ETCC. Objetivo: estudar o uso de ETCC duas vezes por semana por 5 semanas em idosos com CCL. Métodos: o estudo foi controlado, randomizado, duplo-cego com ETCC anódica em 58 idosos acima de 60 anos. Uma corrente de 2,0 mA foi aplicada por 30 minutos durante 10 sessões consecutivas, 2 vezes por semana. O ânodo foi colocado no córtex pré-frontal dorsolateral esquerdo (LDLFC). Os pacientes foram avaliados antes e após 10 sessões pelos testes: CAMCOG, Mini-Exame do Estado Mental (MMSE), Trilhas, Fluência Verbal Semântica - Animais, Boston, Relógio, Memória da Lista de Palavras (WLMT), Dígitos - ordem direta e indireta (WAIS-III e WMS-III) e N-back. Resultados: foram encontradas interações significativas (tempo/grupo) para CAMCOG - funcionamento executivo (χ2 = 3,961, p = 0,047), CAMCOG - fluência verbal (χ2 = 3,869, p = 0,049), CAMCOG - recuperação da memória (χ2 = 9.749, p = 0,004), WMLT - recordação (χ2 = 7,254, p = 0,007). Foi observado um declínio no grupo ETCC após a intervenção para CAMCOG - praxia construtiva (χ2 = 4,371, p = 0,037). Não encontramos diferenças significativas entre os grupos ETCC e placebo para outros testes. Conclusão: A ETCC de 2 mA por 30 min, 2x por semana, por 5 semanas consecutivas, é superior ao placebo (Sham) na melhoria da recuperação de memória, fluência verbal e funcionamento executivo em idosos com CCL.

In vitro Anti-cholinesterase and Anti-oxidant Activity of Three Standardised Polyherbal Products Used for Memory Enhancing in Ethnomedicine of South-East Nigeria

Background: Polyherbal standardised extracts used in ethnomedicine of Eastern Nigeria for memory improvements were evaluated for anti-cholinesterases and anti-oxidant properties.Methods: Anti-cholinesterase, anti-oxidant, and total phenolic and flavonoid contents were established using standard procedures.Results: The three polyherbal extracts exhibited significant concentration dependent acetylcholinesterase (AChE) inhibitory activity (P = 0.001). The highest AChE inhibition was observed with the Neocare Herbal Tea (NHT) with 99.7% (IC50 = 324 μg/mL); whereas the Herbalin Complex Tea (HCT) and Phytoblis Herbal Tea (PHT) exhibited 73.8% (IC50 = 0.2 μg/mL) and 60.6% (IC50 = 0.7 μg/mL) inhibition, respectively, relative to eserine at 100% inhibition (IC50 = 0.9 μg/mL) at 200 μg/mL. The order of percentage increase in inhibition of AChE was NHT > HCT > PHT; while the order of decrease in potency was HCT > PHT > NHT.Radical scavenging activities of HCT, NHT and PHT were 82.13% (IC50 = 0.08 μg/mL), 77.43% (IC50 = 0.01 μg/mL) and 76.28% (IC50 = 0.3 μg/mL), respectively, at 1 mg/mL concentrations. The reducing power revealed a dose-dependent effect, with NHT > PHT > HCT. The order of total phenolics content in the extracts were PHT > HCT > NHT, and for total flavonoids content: PHT > NHT > HCT.Conclusion: The three polyherbal standardised products possess significant acetylcholinesterase inhibitory activity and secondary metabolites that could collectively contribute to their memory-enhancing effects.