A Novel Program to Improve Cognitive Function in Individuals With Dementia Using Transcranial Alternating Current Stimulation (tACS) and Tutored Cognitive Exercises

Abstract

The effects of cognitive exercises on the healthy aging population is controversial. Transcranial alternating current stimulation (tACS) is considered a promising tool for modulating brain oscillation. Research is lacking on its long-lasting cognitive/therapeutic effect. This is the first pilot study to explore the effect of a regimen of cognitive exercises with and without tACS on older adults with dementia. The study groups were 28 individuals (age 56-83 years) enrolled into two groups: Exr Group, who received cognitive exercises only and the Exr + tACS Group who received tACS at 40 Hz simultaneously with cognitive exercises for a period of 4 consecutive weeks, 5 days/week, two 30 min-sessions/day; all the training sessions were tutored. The cognitive exercises were applied using the MindTriggers app. They were assessed at pre and post intervention and also one month after the end of trial (follow-up) with an independent assessment (WMS-IV) as the primary outcome measure. The results show significant cognitive improvement at post-intervention in both groups, while the Exr + tACS protocol lead to superior cognitive improvement at follow-up session. The most important outcomes of this study are: 1) The tutored repeated practice of the MindTriggers app exercises does significantly improve the cognitive functions of older adults with dementia and that that improvement lasts for at least one month after the end of the intervention, and 2) The application of tACS increases the positive effects of cognitive exercises with the positive effect lasting an even longer period of time than exercises alone; in other words we speculate that it may lead to long-term potentiation.

Keywords: alzheimer's; cognitive exercises; dementia; gamma band stimulation; mind triggers app; transcranial alternating current stimulation (tACS); tutoring.

FIGURE 1

The VR building used for spatial orientation assessment.

FIGURE 2

WMS raw scores of all participants of the two groups at baseline, post and follow-up sessions. Vertical axis is the WMS raw scores and horizontal axis is the participants’ number with no particular order. Note that three participants in tACS + Exr and 1 in Exr group missed the follow-up session assessment due to pandemic.

FIGURE 3

The average of primary outcome measure (WMS-IV) (mean ± SE) among participants of the two groups of tACS + Exr (n = 19) and Exr (n = 9) at baseline, post-intervention and follow-up. Both groups showed significant improvement at post-intervention respect to baseline; this improvement was still significant for tACS + Exr group but not for Exr group; see Table 4 for statistical analysis details.

FIGURE 4

The average changes (mean ± SE) of the WMS-IV raw scores among participants of the two groups of tACS + Exr (n = 19) and Exr (n = 9) at post-intervention and follow-up respect to baseline. The changes between the two groups at follow-up session is evident but it was not statistically significant (p = 0.086); see Table 4 for details on statistical analysis details.

FIGURE 5

The average of secondary outcome measure (Spatial Orientation scores) (mean ± SE) among the two groups of tACS + Exr (n = 19) and Exr (n = 9) at baseline, post-intervention and follow-up.