Studying Brain Mechanisms in Psychotic Alzheimer’s Disease

Inclusion Criteria Alzheimer´s disease (AD) participants: * Age 65-85 years old. * Diagnosis of probable AD dementia according to National Institute on Aging-Alzheimer's Association (NIA-AA) criteria. * Mini-Mental State Examination (MMSE) score ≥ 10 and ≤ 26 at the screening visit. * Clinical Dementia Rating (CDR) score ≥ 0.5. * Logical Memory delay score of ≤8 for 16+ years of education, ≤4 for 8-15 years of education, and ≤2 for 0-7 years of education Exclusion Criteria Alzheimer´s disease (AD) participants: * Rosen-modified Hachinski Ischemia Score \> 4 at the screening visit. * History of stroke. * Evidence of a clinically relevant neurological disorder other than probable AD at the screening visit. Participants with insulin dependent type 2 diabetes, a history of CVD, a history of epilepsy, a history of TBI with greater than 15 minutes of loss of consciousness, a movement disorder, autoimmune disease affecting the CNS, or delirium. * Evidence of a clinically relevant or unstable psychiatric disorder, based on DSM-5 criteria, including schizophrenia or other psychotic disorder, bipolar disorder, delirium, or current/active major depression. * History of alcoholism or drug dependency/abuse within the last 5 years before screening. * Presence of metal implants such as pacemakers, ear implants, internal bullet fragments or shrapnel. * Inability to lie flat for 1 hour approximately. * hearing impairment as evidenced by the inability to hear 500, 1000 and 6000 Hz bilaterally on an OAE evaluation. Subjects with hearing aides will be allowed to participate if they meet minimum hearing requirements. Specific Inclusion Criteria for Alzheimer´s disease (AD) with Psychotic symptoms: * All the criteria for AD are met. * Presence of one (or more) of the following symptoms: * Visual or auditory hallucinations (e.g., seeing silent individuals standing in the room, seeing children in the yard, or seeing animals in the house). * Delusions (fixed false beliefs that the patient believes to be true, e.g., that the spouse is unfaithful, that possessions are being stolen, or that one is not who one claims to be). Inclusion Criteria Cognitively Unimpaired Healthy (CUH) participants: * Age 65-85 years old. * No known genetic risk factors for dementia. * No cognitive complaint * Mini-Mental State Examination (MMSE) score ≥ 26 at the screening visit. * Logical Memory delay score of ≥9 for 16+ years of education, ≥5 for 8-15 years of education, and ≥3 for 0-7 years of education Exclusion Criteria Cognitively Unimpaired Healthy (CUH) participants: \- Same criteria as AD participants above.