A Study to Investigate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of RO7812653 in Participants With Early Symptomatic Alzheimer's Disease (eAD)

Inclusion Criteria:

• Probable AD dementia (consistent with National Institute on Aging and Alzheimer'sAssociation (NIA-AA) core clinical criteria for probable AD dementia) [McKhann et al 2011] or Mild Cognitive Impairment (MCI) due to AD (consistent with the NIA-AA coreclinical criteria for mild cognitive impairment due to AD) [Albert et al 2011]).

• Willingness and ability to complete all aspects of the study. The participant shouldbe capable of completing assessments either alone or with the help of the studypartner.

• Fluency in the language of the tests used at the study site.

• Adequate visual and auditory acuity, in the investigator's judgment, sufficient toperform the neuropsychological testing (eyewear and hearing aids are permitted).

• If the participant is receiving symptomatic AD medications, a stable dosing regimenfor at least 8 weeks prior to screening and until randomization is required.

• Agreement not to participate in other research studies for the duration of thisstudy.

Exclusion Criteria:

• Any medical history or evidence of a condition other than AD that may affectcognition.

• Presence of any significant cerebral abnormalities that would contraindicate lumbarpuncture, as assessed on MRI

• Any other significant cerebral abnormalities that the Investigator considersclinically significant

• History of schizophrenia, schizoaffective disorder, major depression or bipolardisorder.'

• Presence of cardiovascular, respiratory, hepatic, renal, gastrointestinal,endocrine, hematological medical conditions which are not stable and adequatelycontrolled or which in the opinion of the investigator could affect the subject'ssafety in the study or interfere with the study assessments