Home-based Brain Stimulation for Memory

Inclusion Criteria: Participants (Ps) * willing and capable to give informed consent for the participation in the study after it has been thoroughly explained * able and willing to comply with all study requirements * an informed consent form was signed * able to read, write, and communicate in English * able to identify an eligible administrator to participate with them in the study Administrators (As) * at least 21 years of age * able to read, write, and communicate in English * self-reported computer proficiency and willingness to learn how to use tACS as defined by "yes" answers to the questions "Do you feel comfortable using a computer?" and "Are you willing to be the primary caregiver for a participant and learn how to administer tACS?" * stated availability during weekdays throughout the study period to administer tACS to the Ps Exclusion Criteria: Participants (Ps) * major psychiatric co-morbidity including major depressive disorder, schizophrenia or psychosis * blindness or other disabilities that prevent task performance * contraindications to tACS, as recorded on a standardized screening questionnaire, which include a reported seizure within the past two years, use of neuroactive drugs, self-reported presence of specific implanted medical devices (e.g., deep brain stimulator, medication infusion pump, cochlear implant, pacemaker, etc.) * the presence of any active dermatological condition, such as eczema, on the scalp a score of 18 or less on the Montreal Cognitive Assessment (MoCA) during the in-person screen * an inability to understand study procedures following review of the Informed Consent form * Understanding will be assessed by asking the participant to answer the following three questions: 1) What is the purpose of this study? 2) What are the risks of study involvement? 3) If you decide to participate, are you allowed to withdraw from the study at any time? Answers will be recorded by study personnel on the "Assessment of Protocol Understanding" form (see attached). Insufficient understanding will be defined by one or more incorrect answers, as determined at the discretion of the investigator Administrators (As) * mild cognitive impairment defined by a MoCA score ≤26 during the in-person screen * insufficient understanding of study procedures following review of the Informed Consent form * Understanding will be assessed by asking the participant to answer the following three questions: 1) What is the purpose of this study? 2) What are the risks of study involvement? 3) If you decide to participate, are you allowed to withdraw from the study at any time? Answers will be recorded by study personnel on the "Assessment of Protocol Understanding" form (see attached). Insufficient understanding will be defined by one or more incorrect answers, as determined at the discretion of the investigator. * poor eyesight, severe arthritis in the hands, pain, deformity or other condition that interferes with successful administration of tACS