P30: Effects of Cognitive Stimulation Combined with Transcranial Direct Current Stimulation on Cognitive Performance and Cortical Excitability in Amnestic Mild Cognitive Impairment

Abstract

Introduction: Transcranial Direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) are neuromodulatory techniques capable of modifying the altered cerebral hyperexcitability in amnestic mild cognitive impairment (aMCI). Cortical excitability can be estimated with motor evoked potentials (MEPs) and synaptic plasticity can be induced with a 5 Hz rTMS paradigm applied to the motor cortex (M1). An increase in MEP amplitude reflects a better capacity for plasticity in M1, and these measures can, in turn, be associated with cognitive performance. Cognitive stimulation (CS) and tDCS in aMCI can modify excitability and improve cognition.

Objectives: Study the effect of the combination of CS and tDCS (real vs. placebo) on cognitive performance and cortical excitability.

Methods: Randomized, double-blind, placebo-controlled clinical trial in aMCI. The diagnosis was established through a clinical evaluation by a psychogeriatrician and a neuropsychological assessment. To determine the effect of the interventions, evaluations were conducted at two time points: before (T0) and after administering 9 sessions of CS and 15 sessions of tDCS over three weeks (T1). The evaluations included: MEP amplitude, Montreal Cognitive Assessment (MoCA), and Screening for Cognitive Impairment in Psychiatry (SCIP-S). For data analysis, ARTool in RStudio was used to perform aligned rank transformation for non-parametric analysis of variance in factorial models with fixed and random effects, applying a factorial ANOVA for each response variable.

Results: A total of 18 participants were enrolled (real n = 8 and placebo n = 10). Comparing T0 and T1, differences were found in both groups in MEP amplitude after applying the paradigm (F = 5.479; p = 0.032) as well as in the total MoCA score (F = 4.808; p = 0.043). When comparing the groups, differences were found in the delayed verbal learning domain assessed with SCIP-S (F = 6.038; p = 0.025) and in MEP amplitude (F = 6.165; p = 0.024). No differences were found in any of the evaluations when studying the effect of the GroupxTimeinteraction.

Conclusions: Both groups benefit from cognitive stimulation, and the use of tDCS does not appear to enhance the cognitive effect or the MEPs. It seems that cognitive stimulation alone is capable of modifying cortical excitability and improving cognitive performance.