Investigational Dementia Treatment Study

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.