Effects of transcranial direct current stimulation (tDCS) on visuospatial working memory in young adults - preliminary results

Growing interest in non-invasive methods, such as transcranial direct current stimulation (tDCS), to enhance cognitive functioning in healthy individuals has led to numerous studies. tDCS is a commonly used non-invasive brain stimulation method, and previous research has demonstrated its effectiveness in improving cognitive functions. This study aimed to evaluate whether anodal stimulation of the area F3 and cathodal stimulation of the area Fp2 improves visuospatial attention and block span in young adults when compared to a placebo.The study included 60 participants in early adulthood, with no history of neurological or psychiatric diseases, divided into two groups matched for age and sex. •Group A: 30 participants (18 women, 12 men; aged 21-35 years) underwent 10 sessions of neurostimulation (30 min, 2mA). •Group B: 30 participants (18 women, 12 men; aged 21-35 years) underwent 10 sessions of sham neurostimulation (30 min, 0.5mA). In this procedure after 20 seconds the current is turned off, and no further electrical stimulation is delivered. Visuospatial attention and block span were assessed using the Corsi computerized block test, in which the participant repeated a sequence of blocks displayed on a screen. Assessments were conducted at once before and after the neurostimulation cycle.Analysis revealed that in Group A, there was a significant positive correlation between initial scores and post-stimulation scores. There was a moderate correlation for total visuospatial attention scores and a strong correlation for block span scores in the computerized Corsi block test. In Group B, no significant differences were found between the first and second assessments for both total scores and block span scores. Therefore, the effectiveness of the proposed tDCS protocol in improving visuospatial attention and block span was observed in Group A, but not in Group B, which had undergone sham stimulation.Anodal stimulation of the left DLPFC and cathodal stimulation of the right supraorbital region significantly enhance visuospatial attention and block span in healthy young adults, particularly those with lower baseline abilities, compared to a placebo. Individual responses most likely vary due to anatomical and morphological differences affecting electric field distribution. The underlying mechanism remains unclear, and future research should focus on inter-individual differences to improve the efficiency and reproducibility of tDCS.