A Study of Lanabecestat (LY3314814) in Participants With Mild Alzheimer's Disease Dementia

Inclusion Criteria: * Participant must meet the National Institute on Aging (NIA) and the Alzheimer's Association (AA) (NIA-AA) criteria for probable AD dementia. * MMSE score of 20 to 26 inclusive at screening visit. * For a diagnosis of mild AD dementia, participant must have a CDR global score of 0.5 or 1, with the memory box score ≥0.5 at screening. * Evidence of amyloid pathology. * The participant must have a reliable study partner with whom he/she cohabits or has regular contact. Exclusion Criteria: * Significant and/or current neurological disease affecting the central nervous system, other than AD, that may affect cognition or ability to complete the study, including but not limited to, other dementias, repetitive head trauma, serious infection of the brain, Parkinson's disease, epilepsy, or cervicocranial vascular disease. * Participants with any current primary psychiatric diagnosis other than AD if, in the judgment of the investigator, the psychiatric disorder or symptom is likely to confound interpretation of drug effect, affect cognitive assessment, or affect the participant's ability to complete the study. Participants with history of schizophrenia or other chronic psychosis are excluded. * Within 1 year before the screening visit or between screening and randomization, any of the following: myocardial infarction; moderate or severe congestive heart failure, New York Heart Association class III or IV; hospitalization for, or symptoms of, unstable angina; syn…