Inclusion Criteria - Participants must have a confirmed diagnosis of Alzheimer's disease (AD), specifically at the mild (stage 4) or moderate (stage 5) dementia stages, as defined by the National Institute on Aging and Alzheimer's Association (NIA-AA) core clinical criteria. The diagnosis of AD pathology must be confirmed through the 2024 revised NIA-AA Workgroup criteria using a stepwise diagnostic approach. - Participants must have an Mini-Mental State Examination (MMSE) score ranging from 12 through 22, inclusive, at the time of screening. - Participants must have a designated caregiver who maintains adequate contact (around 10 hours per week or more) and is willing to attend all study visits. The caregiver must also be responsible for reporting on the participant's condition, overseeing medication compliance, and consenting to their involvement in both their own and the participant's study-related activities. - Participants on acetyl choline esterase inhibitors (AChEIs) and/or memantine, must have been on a stable dosage for at least 12 weeks prior to screening, and agree to maintain this stable dose for the study duration. Exclusion Criteria - Participants must not present with any significant or severe medical conditions that could compromise their safety, the ability to comply with or complete the study, or the integrity of the study results. This includes any grade of hepatic impairment. - Participants must not have any primary psychiatric diagnoses such as major depression, schizoaffective disorder, or bipolar disorder, and those with severe psychiatric symptoms that could complicate the interpretation of treatment effects, impair cognitive assessment, or impact study completion. - Participants must not have a history of schizophrenia or other chronic psychosis, as well as those who have previously been exposed to KarXT or are currently undergoing treatment with disease-modifying anti-amyloid therapies for AD within the past 6 months prior to screening. - Participants must not have significant pathological findings on brain magnetic resonance imaging (MRI) at screening that could affect safety or interfere with study procedures. - Other protocol-defined Inclusion/Exclusion criteria apply.