A Phase 2a Multicenter, Randomized, Double-Blind, Parallel Group, 26-Week, Placebo-Controlled Study of SUVN-502 in Subjects With Moderate Alzheimer's Disease Currently Treated With Donepezil Hydrochloride and Memantine Hydrochloride

• Has a diagnosis of probable Alzheimer's disease based on the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria at least 1 year prior to the screening visit.

• Has a score between 12 and 20 inclusive on the MMSE at the screening and baseline visits.

• Has a MRI or CT scan performed within 12 months prior to screening with findings consistent with the diagnosis of dementia due to Alzheimer's disease without any other clinically significant comorbid pathologies.

• Must be receiving treatment with stable doses of donepezil HCl and memantine HCl for at least 3 months prior to the screening visit

• Availability of an eligible and reliable caregiver

• Must be living in the community or an assisted living facility.

• Must be ambulatory or ambulatory aided (use of cane or walker).

• Is not pregnant or planning to become pregnant during the study.

• Subject (or subject's legally acceptable representative) and caregiver must sign an Informed Consent to participate in the study.