A Phase 1, Open-label, Multi-part Study to Evaluate Pharmacokinetics, Absolute Bioavailability, Safety, Tolerability, and Immunogenicity of Single-Dose of BMS-986446 Following Intravenous and Subcutaneous Administrations in Healthy Adults and Multiple Doses of BMS-986446 in Participants With Early Alzheimer's Disease.

Inclusion Criteria * Participants must have a BMI of 18.0 to 35.0 kg/m2. * For Parts A and B: Participants must be healthy as determined by medical history, Physical Examination (PE), neurological examination, vital signs, 12-lead ECG, Columbia Suicide-Severity Rating Scale (C-SSRS), and clinical laboratory evaluations. * For Part C: Participants must meet diagnostic criteria for MCI or mild AD dementia, consistent with the National Institute on Aging and the Alzheimer's Association (NIA-AA) diagnostic criteria. * For Part C: Participants must have an Mini Mental State Examination (MMSE) scor…