A Study of JNJ-63733657 in Participants With Early Alzheimer's Disease

Open to people ages 55-80

• Early Alzheimer's disease (AD): Gradual and progressive subjective decline in the participant's cognition over at least the past 6 months, as reported by the participant and informant (study partner) and Clinical Dementia Rating-Global Score (CDR-GS) of 0.5 and memory box score greater than or equal to (>=) 0.5 at screening
• Participants must have positive tau PET results
• Able to read and write and with a minimum 5 years of formal education as reported by participant and study partner at screening
• Have a designated study partner who has adequate literacy to participate and be judged to have high likelihood of completing the study with the participant
• Male participants must agree not to donate sperm for the purpose of reproduction during the study and up to 16 weeks after receiving the last dose of study intervention

• Participants with CDR GS >=2 at predose baseline Clinical Dementia Rating (CDR) administration
• Participants who fulfill diagnostic criteria for Mild Cognitive Impairment (MCI) or dementia/mild or major neurocognitive disorder suspected to be due to any etiology other than AD (example, Parkinson's disease, cerebrovascular disease, normal pressure hydrocephalus, head injury, drug or alcohol abuse/dependence, anoxic brain injury, (Et cetera[etc])
• Geriatric Depression Scale (GDS) 30 score greater than (>) 12
• Hachinski Ischemic Scale (HIS) >4
• Has received medications that affect the central nervous system (CNS), except treatments for AD, for less than 2 months; that is, doses of chronic medications that effect the CNS should be stable for at least 2 months before the start of screening. If a participant has recently stopped a chronic medication that effects the CNS, he or she must have discontinued treatment at least 2 months before the start of screening. Chronic use of benzodiazepines is not permitted