This is a multicenter randomized, double-blind, placebo-controlled Phase 2 study designed to evaluate the efficacy, safety, and tolerability of two doses of CT1812 compared to placebo in participants diagnosed with early Alzheimer's disease.

This is a multicenter randomized, double-blind, placebo-controlled Phase 2 study designed to evaluate the efficacy, safety, and tolerability of two doses of CT1812 compared to placebo for approximately 18 months (72 weeks) in approximately 540 participants diagnosed with early Alzheimer's disease

Participants will be randomized 1:1:1 to receive either 100mg or 200mg of CT1812 or placebo. CT1812 or placebo will be administered as 2 capsules to be taken orally once daily.

Inclusion Criteria:

1. Ages 50-85 years.
2. Diagnosis of either MCI due to AD or mild AD dementia.
3. MMSE 20-30 (inclusive).
4. Amyloid PET scan of the brain or CSF biomarkers consistent with AD.
5. Neuroimaging (MRI) obtained during screening consistent with the clinical diagnosis of Alzheimer's disease, as based on central read.

Exclusion Criteria:

1. Screening MRI of the brain indicative of significant abnormality.

2. Clinically significant abnormalities in screening laboratory tests.

3. Clinical or laboratory findings consistent with:

   1. Other primary degenerative dementia, (dementia with Lewy bodies, fronto-temporal dementia, Huntington's disease, Creutzfeldt-Jakob Disease, Down syndrome, etc.).
   2. Other neurodegenerative condition (Parkinson's disease, amyotrophic lateral sclerosis, etc.).
   3. Other infectious, metabolic or systemic diseases affecting the central nervous system (syphilis, present hypothyroidism, present vitamin B12, other laboratory values etc.)

4. A participant known to be actively infected with hepatitis B or hepatitis C at screening. History of acute/chronic hepatitis B or C and/or carriers of hepatitis B (seropositive for hepatitis B surface antigen [HbsAg] or anti-hepatitis C [HCV] antibody). Participants who have evidence of resolved hepatitis infection (e.g., HCV RNA negative) may be considered following discussion with the Medical Monitor.

5. A current DSM-V diagnosis of active major depression or GDS > 6, schizophrenia, or bipolar disorder.