A 28-Day Study of GAL-101 in Participants With Mild to Moderate Alzheimer's Disease

Inclusion Criteria: * Male or female participants aged 50 to 85 years, inclusive. * Clinical diagnosis of Alzheimer's disease at the mild or moderate dementia stage (Stages 4 or 5) according to the 2018 National Institute on Aging and Alzheimer's Association criteria * Evidence of amyloid-beta pathology based on cerebrospinal fluid biomarkers, amyloid-beta positron emission tomography, or plasma phosphorylated tau 217. * Evidence of cognitive decline during the previous year. * Availability of a reliable trial partner, caregiver, or legal representative who has contact with the participant for at least 10 hours per week and can support study participation. * Able and willing to provide informed consent and comply with study requirements. * In sufficiently good health, in the investigator's opinion, to participate in the study. * If receiving an acetylcholinesterase inhibitor or memantine, treatment must be at a stable dose for the protocol-specified period. Exclusion Criteria: * A neurological, psychiatric, cerebrovascular, or other medical condition that could explain the participant's cognitive impairment, interfere with study assessments, or create an unacceptable safety risk. * Previous treatment with anti-amyloid-beta immunotherapy. * Participation in another interventional clinical study or receipt of an investigational drug within 3 months before screening. * Use of prohibited medications or substances that could affect cognition, electroencephalography assessments, safety, or interpretation of the study results. * Clinically significant or unstable cardiovascular, respiratory, renal, hepatic, metabolic, infectious, or malignant disease. * Active major depression, schizophrenia, bipolar disorder, or clinically significant suicide risk. * Known or suspected hypersensitivity to GAL-101, placebo, or their components. * A scalp condition that would prevent adequate electroencephalography assessment. * Inability to comply with the study schedule or procedures. * Any other condition that, in the investigator's opinion, makes the participant unsuitable for the study.