Study to Evaluate the Effects of NMRA-323511 Among Healthy Elderly and Adults With Agitation Associated With Dementia Due to Alzheimer's Disease

Inclusion Criteria:

Part A

• Healthy participants

• Age 65 to 80 years

• Body mass index (BMI) ≥18.0 and ≤32.0 kg/m^2 at the screening and check-in visit

Part B

• Participants aged 55 to 90 years

• Diagnosis of probable AD or Alzheimer's clinical syndrome according to the NationalInstitute of Aging-Alzheimer's Association criteria at least 12 months prior toscreening

• Agitation meets the International Psychogeriatric Association (IPA) consensusdefinition

• Mini-Mental State Examination (MMSE) score = 5 - 24 (mild to severe dementia) atscreening

Exclusion Criteria:

Part A

• Participant is actively suicidal

• Is mentally or legally incapacitated or has significant emotional problems at thetime of the screening visit

• Diagnosis of epilepsy taking anticonvulsants for seizure control, history ofseizures

Part B

• Dementia or memory impairment due to a reason other than AD

• Clinically significant neurologic disorder other than AD

• Have any clinically significant and uncontrolled medical condition

Note: Other protocol defined inclusion/exclusion criteria may apply