This is a multi-center, randomized, double-blind, placebo-controlled, parallel group 36 week multicenter Phase 2 study of two doses of CT1812 in adults with mild to moderate Alzheimer's Disease (AD).

This is a multi-center, randomized, double-blind, placebo-controlled, parallel group 36 week multicenter Phase 2 study of two doses of CT1812 in adults with mild to moderate Alzheimer's Disease (AD).

This Phase 2 study is designed to evaluate the safety of two doses of CT1812 administered once daily for 6 months in adults aged 50 to 85 who have been diagnosed with mild to moderate Alzheimer's disease. Randomized participants will receive 100 mg of CT1812, 300 mg of CT1812, or placebo once daily for 182 days. Exploratory endpoints that evaluate the effect of CT1812 on biomarkers are also included.

Inclusion Criteria:

1. Men, and women of non-childbearing potential, 50-85 years of age inclusively, with a diagnosis of mild to moderate Alzheimer's disease according to the 2011 NIA-AA criteria and at least a 6 month decline in cognitive function documented in the medical record.

   i) Non-childbearing potential for women is defined as postmenopausal (last natural menses greater than 24 months) or undergone a documented bilateral tubal ligation or hysterectomy. If last natural menses less than 24 months, a serum FSH value confirming post-menopausal status can be employed.

   ii) Male participants who are sexually active with a woman of child-bearing potential must agree to use condoms during the trial and for 3 months after last dose unless the woman is using an acceptable means of birth control. Acceptable forms of birth control include abstinence, birth control pills, or any double combination of: intrauterine device (IUD), male or female condom, diaphragm, sponge, and cervical cap.

2. Diagnostic confirmation by amyloid PET with florbetaben or another approved amyloid PET ligand. Previous amyloid imaging study with a positive result will be accepted. If none is available, then amyloid PET will be conducted during screening. Diagnostic confirmation by a CSF sample collected at the screening visit lumbar puncture in place of amyloid PET will also be acceptable

3. Neuroimaging (MRI) obtained during screening consistent with the clinical diagnosis of Alzheimer's disease and without findings of significant exclusionary abnormalities (see exclusion criteria, number 4). An historical MRI, up to 1 year prior to screening, may be used as long as there is no history of intervening neurologic disease or clinical events (such as a stroke, head trauma etc.) and the subject is without clinical symptoms or signs suggestive of such intervening events.).

4. MMSE 18-26 inclusive.

Exclusion Criteria:

1. Screening MRI (or historical MRI, if applicable) of the brain indicative of significant abnormality, including, but not limited to, prior hemorrhage or infarct >1 cm3, >3 lacunar infarcts, cerebral contusion, encephalomalacia, aneurysm, vascular malformation, subdural hematoma, hydrocephalus, space-occupying lesion (e.g. abscess or brain tumor such as meningioma). If a small incidental meningioma is observed, the medical monitor may be contacted to discuss eligibility..

2. 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. Seizure disorder.
   4. Other infectious, metabolic or systemic diseases affecting the central nervous system (syphilis, present hypothyroidism, present vitamin B12 or folate deficiency, other laboratory values etc.).

3. A current DSM-V diagnosis of active major depression, schizophrenia or bipolar disorder. Subjects with depressive symptoms successfully managed by a stable dose of an antidepressant are allowed entry.

4. Clinically significant, advanced or unstable disease that may interfere with outcome evaluations.