A Study of a Potential Disease Modifying Treatment in Individuals at Risk for or With a Type of Early Onset AD Caused by a Genetic Mutation

Inclusion Criteria: 1. Provide written informed consent, signed, and dated by the participant and study partner, or by the participant's legally authorized representative if applicable, according to local regulations for the ICF and, if applicable, country specific ICFs. 2. Participant is at least 18 years old. 3. People of childbearing potential 1. Must have a negative serum pregnancy test at screening (V1) 2. Must agree not to try to become pregnant from the time of signed ICF until twenty (20) weeks after the last dose of any study drug. 3. Must agree not to breastfeed from the time of signed ICF until twenty (20) weeks after the last dose of any study drug. 4. If partner is not sterilized, must agree to use highly effective contraceptive measures, methods that can achieve a failure rate of less than 1% per year when used consistently and correctly from screening (V1) until twenty (20) weeks after last dose of any study drug. i. combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation: oral, intravaginal, transdermal ii. progestogen-only hormonal contraception associated with inhibition of ovulation: oral, injectable, implantable iii. intra-uterine device (IUD) iv. intrauterine hormone-releasing systems (IUS) v. bilateral tubal occlusion vi. vasectomized partner (only when this is the only partner) vii. true sexual abstinence when this is in line with the preferred and usual lifestyle of the participant. (Periodic abstinence \[e.g., calendar, ovulation, symptothermal, post-ovulation methods\], declaration of abstinence for the duration of exposure to IMP, and withdrawal are not acceptable methods of contraception) 4. Mutation Status: 1. Participant is a carrier of a mutation in an APP, PSEN1, or PSEN2 gene that is associated with DIAD or does not know their mutation status and there is a mutation in their family pedigree that puts them at a direct risk of inheriting the known mutation; 2. Participant is -25 to -11 years from predicted age of cognitive symptom onset based on their mutation type or family pedigree Note: If the at-risk parent is deemed a non-carrier through confirmed genetic testing at any time during the study, the participant will be withdrawn. 5. Cognitive status of participant is normal (CDR-SB 0). 6. Fluency in DIAN-TU trial approved language and evidence of adequate premorbid intellectual functioning. Participants must be fluent in languages for which cognitive and clinical measures have been translated and validated for use in the DIAN-TU. Fluency is generally defined as daily or frequent functional use of a language generally from birth or a young age. In cultures where multiple languages are spoken or for participants who are multilingual, determination as to whether a participant's level of fluency in languages for which clinical and cognitive measures are available meets qualification for the study should be made by the site PI. 7. Adequate visual and auditory abilities to perform all aspects of the cognitive and clinical assessments. 8. Receiving stable doses of medication(s) for the treatment of non-excluded medical condition(s) for at least 30 days prior to baseline visit (V2) with the exceptions of medications taken for episodic conditions (e.g., migraine abortive therapy, antibiotics, and other medications for upper respiratory and gastrointestinal ailments). 9. Has a study partner who in the PI's judgment can provide accurate information as to the participant's cognitive and functional abilities, who agrees to provide information at the study visits that require study partner input for scale completion, and who signs the necessary ICF, if applicable. 10. Agrees not to donate blood or blood products for transfusion from the time of Screening (V1) for a study drug arm, for the duration of the study, and for 5 half lives after the final dose of study drug. 11. In the opinion of the PI, the participant will be compliant and have a high probability of completing the study. 12. Willing to complete all study-related testing, evaluations, and procedures. Exclusion Criteria: 1. Significant neurologic disease (other than AD) or psychiatric disease that may currently or during the study affect cognition or the participant's ability to complete the study. This would include disorders such as: recent or severe head trauma causing cognitive change, seizure disorder, neurodegenerative disease other than DIAD, hydrocephalus, cerebral/spinal hematoma, inflammatory disease, CNS infection (e.g., encephalitis or meningitis), neoplasm, toxic exposure, metabolic disorder (including hypoxic or hypoglycemic episodes) or endocrine disorder; psychiatric disorders such as schizophrenia, schizoaffective disorder, bipolar disorder or major depression, or any other psychiatric condition/disorder which could significantly interfere with the participant's cooperative participation (e.g., prominent anxiety, agitation or behavioral problems). Disorders that are controlled medically or remote history of these disorders (e.g., history of febrile seizures in childhood) that are not likely to interfere with cognitive function and compliance with study procedures are not exclusionary. 2. At high risk for suicide, e.g., significant suicidal ideation or attempt within last 12 months, current major depression (as defined in Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition \[DSM-V\]), or increased suicide risk based on screening Columbia Suicide Severity Rating Scale (C-SSRS). Current stable mild depression or current use of antidepressant medications are not exclusionary. 3. History of clinically evident stroke or history of clinically important carotid or vertebrobasilar stenosis, plaque, or other prominent risk factor for stroke or cerebral hemorrhage (including atrial fibrillation and anticoagulation, documented transient ischemic attack \[TIA\] in the last 12 months) that may be interferin