Can gentle brain pulses sharpen aging minds?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Men and women * Age: 65 to 84 years * English speaking * Physically mobile with no history of balance difficulties or major falls * For the typically-aging older adult group, phone screening performance on the TICS must be greater than or equal to 33 points, and cognitive performance of 26 points or greater on the MoCA and a Sum of Boxes score of 0 on the Clinical Dementia Rating scale administered to the participant's informant at the initial visit * For the Mild dementia group, phone screening performance on the TICS must be between 21 and 32 points, and subsequent cognitive performance of on the MoCA must be \<23 with a CDR Sum of Boxes score between 4.5 and 9.0 as administered to the participants known informant at the initial visit. Exclusion Criteria: * Neurological disorders unrelated to dementia / AD (e.g., Parkinson's disease, stroke, seizures, traumatic brain injury) * Evidence of greater-than-mild dementia/AD (based on informant CDR Sum of Boxes score greater than 9.0 or MoCA \<10) * Past opportunistic brain infection * Major psychiatric illness (schizophrenia, intractable affective disorder, current substance dependence diagnosis or severe major depression and/or suicidality) or any history of agitation and/or delirium * Unstable (e.g., cancer other than basal cell skin) and chronic (e.g., diabetes mellitus) medical conditions * MRI contraindications (e.g., pregnancy, claustrophobia, metal implants that are contraindicated for MRI and TPS) * Physical impairment precluding motor response or lying still for one hour and inability to walk two blocks without stopping or without balance difficulties * Drug exclusions include those medications that are known to have cognitively sedating or altering effects as well medications with a strong anticholinergic burden or CNS effects. Participants should be stable on any recently altered medications/dosages for at least four weeks prior to beginning the study. Medications will be reviewed during the interview for the purpose of identification of contraindicated pharmacological agents with common cognitive side-effects * Other history of medical conditions that may increase risk of cerebrovascular events, including prior heart attack, cardiac arrhythmia such as atrial fibrillation * Hearing or vision deficits that will not allow for reliable standardized cognitive assessment; i.e. colorblindness, inability to hear through headphones (with or without hearing aids), macular degeneration or other significant diseases that cause severe loss of vision. If vision is corrected with lenses to appropriate levels, then participant will be eligible * Left-handedness and ambidextrousness, as these individuals have a higher percentage rate of atypical functional lateralization for brain functions, which would significantly interfere with interpretability of brain data * Hemophilia or other blood clotting disorders or thrombosis * Corticosteroid treatment within the last six weeks before the first treatment