This research investigates the effect of active versus sham tACS paired with cognitive exercises in a regimen protocol of weeks, everyday. The study design is a one-time crossing over design in which participants are randomized into two groups: One group will receive active treatment for 4 weeks, then 8 weeks of no treatment followed by another 4 weeks of treatment but with sham. The other group will start with sham and end up with active treatment. The study is double-blind; thus, neither participants, nor the assessors know the group assignment.

The Intervention is applying tACS either active or sham paired with cognitive exercises (MindTriggers app games).

Note: The above study will run at both University of Manitoba (U of M) and Aster Gardens residence. However, at Aster Gardens Residence only questionnaire type of assessments will be run, while in U of M, the investigators will have three other major assessments as well. In addition, the investigators will run the assessments at the Aster Gardens Residence through online sessions.

This research will investigate the effect of applying transcranial alternating current stimulation (tACS) when paired with cognitive exercises on older adults in a placebo-controlled double-blind study with statistical rigor. In addition, the investigators will investigate and explore novel technological methods not only to monitor the plausible changes due to intervention but also to predict the response of a participant to the intervention at baseline. Since most technological intervention on dementia have a demanding and costly protocol, it would be of great interest to have a reliable prediction of a participant to a treatment at baseline; that would lead to personalized optimum treatment strategy. The investigators will use Electrovestibulography (EVestG), Egocentric Spatial Assessment using our Virtual Reality Navigation (VRN) and functional near infrared spectroscopy (fNIRS) measurements and analysis to develop the monitoring and predicting technologies. EVestG is a non-invasive measure of the vestibuloacoustic system in both background (no motion) and in response to passive whole-body tilt stimuli. The investigators hypothesize there is a direct link between vestibular system deficiencies and Alzheimer's. VRN measures how people orient themselves in a non-familiar environment; the investigators hypothesize it is deteriorated significantly in Alzheimer's even at its onset. fNIRS measures oxygenated and deoxygenated blood flow to the brain and it may help to understand neuronal changes due to intervention.

Inclusion Criteria:

• ability to read, write and speak English fluently

Exclusion Criteria:

• Being diagnosed with Parkinson's, Parkinsonian dementia, Huntington disease, speech significant aphasia and intellectual disability, major depression/anxiety, bipolar disorder, schizophrenia or any other major mood disorder
• Having a History of epileptic seizures or epilepsy
• Inability to adequately communicate in English
• Impaired vision or hearing severe enough to impair performance in cognitive tests
• Current substance abuse disorder
• Currently participating in another therapeutic study for dementia
• Plan to change the medication during this study's period

The group assignment is known only by the study coordinator and the PI. Group assignment will be randomized into either Group 1 or Group 2 using PROC PLAN procedure of SAS randomization. The group assignment of a participant could potentially be unblinded on compassionate ground (e.g., if a participant comes from a different city for the duration of the study) or request of the participant or any emergency situation (although very rare). In that case the participant's data may be excluded from the analysis totally or depending on when this unblinding occur, half of the data might be usable for analysis (if unblinding occur during the waiting period before crossing over). The unblinding decision will be made by the PI.