Evaluation of NBI-1117567 in Participants With Mild to Moderate Alzheimer's Disease (AD) Taking a Background Acetylcholinesterase Inhibitor

Key Inclusion Criteria: * Participant has a primary diagnosis of mild to moderate AD prior to screening. * Participant is receiving a well-tolerated treatment with an acetylcholinesterase inhibitor (donepezil, galantamine, or rivastigmine) at a stable dose for at least 3 months prior to the Screening Visit and is required to continue the same treatment at the same dose level throughout the study. * Negative pregnancy test at screening and Day 1 for participants of childbearing potential. * Participant is willing and able to comply with all study procedures and restrictions in the opinion of the investigator. Participant can follow instructions and understand and perform all study procedures, including cognitive assessments in the opinion of the investigator. Key Exclusion Criteria: * Pregnant (that is, positive pregnancy test at screening, or baseline \[Day 1\]) or lactating, or plans to become pregnant during the study. * Participant has other medical or neurological condition or prior clinical findings indicative of alternate or additional causes of cognitive impairment, including but not limited to vascular dementia, multi-infarct dementia, normal pressure hydrocephalus, Parkinson's disease, dementia with Lewy bodies, frontotemporal dementia, multiple sclerosis, amyotrophic lateral sclerosis, hypoxic cerebral damage, encephalitis, central nervous system (CNS) infection, chronic traumatic encephalopathy, and history of head injury with loss of consciousness. * Participant has an unstable medical condition within the 3 months prior to screening or clinically relevant medical condition interfering with the study as judged by the investigator, as determined from the medical history review and the physical examinations obtained during screening. * Participant has any primary psychiatric condition or severe psychiatric symptom that in the opinion of the investigator may interfere with the participant's ability to participate in the study or impact the interpretation of study results. * Participant is undergoing psychological therapy interventions for cognition in AD. Participants undergoing cognitive behavioral therapy for conditions other than AD must be stable for 3 months prior to Day 1 and during the study. * Participant has previously participated in an interventional clinical study within the preceding 180 days, or 5 half-lives of the experimental treatment, whichever is longer. Note: Other protocol-defined inclusion and exclusion criteria may apply.