Cholinergic Deep Brain Stimulation for Alzheimer's Disease

Inclusion Criteria: * Probable, early-stage AD, as defined by NIA-AA 2018 criteria, including amnestic Mild Cognitive Impairment (MCI) * Clinical Dementia Rating (CDR) global score of 0.5-1.0 with a memory box score of at least 0.5 * MMSE ³ 23 * Stable cognitive enhancer medication equivalent to 10 mg/day donepezil or less for at least 60 days * Stable other medications (e.g., psychotropics) * Valid informed consent if female, subjects who are post-menopausal or surgically sterile or willing to use birth control methods for the duration of the study * an available caregiver willing to participate * subject is living at home and likely to remain at home for the study duration. Exclusion Criteria: * Active or unstable psychiatric illness * Inability to tolerate general anesthesia. * Another concurrent CNS condition or clinical co-morbidity interfering with the study (ie, stroke, Parkinson's disease, Lewy-Body dementia or other form of dementia, other evidence of significant structural brain pathology). * Current major psychiatric disorder such as schizophrenia, bipolar disorder or major depressive disorder based on psychiatric consult at screening visit * Verbal IQ\<85 * Contraindication regarding anesthesia, stereotactic operation, MRI (e.g. claustrophobia, or implants), or PET (e.g. insulin dependent diabetes) procedures * Inability to undergo PET or MRI imaging * Active alcohol or substance abuse as defined by DSM5 * Is unable or unwilling to comply with protocol follow-up requirements * Is actively enrolled in another concurrent clinical trial. * Terminal illness associated with expected survival of \<12 months