The purpose of this study is to learn more about the safety, effectiveness and tolerability of the study drug called Benfotiamine which may delay or slow the progression of the symptoms of early Alzheimer's disease.

This is a randomized, double-blind, placebo-controlled 18-month clinical trial of benfotiamine in early AD. This trial will include a seamless phase 2A-2B design with a randomized total sample of 406 participants. Participants who are randomized but drop out prior to study drug exposure will be replaced.

Phase 2A of the trial will randomize approximately 150 participants total, in a 1:1:1 to treatment with 1200 mg/day benfotiamine, 600 mg/day benfotiamine or placebo. The primary objective of phase 2A is to determine the highest safe and well tolerated dose of benfotiamine (600 mg or 1200 mg), as evaluated by the rate of tolerability events (TEs), for advancement to long-term 72 week exposure. The highest tolerated dose of benfotiamine will be carried forward from phase 2A to phase 2B.

At the start of phase 2B, all participants enrolled in the two phase 2A active dose arms will receive a new supply of benfotiamine at the selected phase 2B dose. All phase 2A participants will be included in the phase 2 intent-to-treat efficacy population, as assigned to active or placebo treatment. The primary objective of phase 2B is to assess efficacy of benfotiamine on global function and cognition over 72 weeks. In phase 2B, a composite cognitive and functional measure as well as PD biomarkers will be used to evaluate efficacy during the extended treatment period. Phase 2B will also evaluate longer-term safety and tolerability of benfotiamine treatment over 72 weeks.

Key Inclusion Criteria:

• Aged 50 to 89 (inclusive) at screening
• Mild Cognitive Impairment (MCI) due to AD or Mild dementia due to AD according to workgroups of the Diagnostic Guidelines of the National Institute on Aging and Alzheimer's Association (NIA-AA)
• Mini-Mental State Examination (MMSE) score 20-30 inclusive at screening-. Montreal Cognitive Assessment score (MoCA) < 26 at screening
• Clinical Dementia Rating (CDR) global score of 0.5 or 1 with memory score of greater or equal to 0.5 at screening
• Positive plasma AD biomarker signature
• Participants who are treated with FDA-approved acetylcholinesterase inhibitors (AchEI)and/or memantine will have to be on a stable dosage regimen for at least 3 months prior to screening.
• Participants must have a study partner who has frequent interaction with them (approximately >3-4 times per week), will be available for all clinic visits in person or remotely, and can assist in compliance with study procedures.
• Female participants must be post-menopausal for at least one year or surgically sterile(bilateral tubal ligation, hysterectomy, or bilateral oophorectomy) for at least 6 months prior to screening.
• Fluent in English or Spanish to ensure compliance with cognitive testing and study visit procedures.
• Ambulatory, or able to walk with an assistive device.
• Provision of informed consent from the participant (or the participant's legally authorized representative (LAR) if unable to provide consent) and the study partner.

Key Exclusion Criteria:

• Significant neurological disorder other than AD (e.g. hypoxia, stroke, traumatic brain injury
• Significant neurodegenerative diseases, other than AD, and causes of dementias, Parkinson's disease and Huntington's disease, vascular dementia, CJD (Creutzfeldt-Jakob disease), LBD (Lewy Body dementia), PSP (Progressive Supranuclear Palsy), AIDS (Acquired Immunodeficiency Syndrome), or NPH (normal pressure hydrocephalus).
• Meeting Diagnostic Criteria for Possible AD according to workgroups of the Diagnostic Guidelines of the NIA-AA.
• A current diagnosis of uncontrolled Type I or Type II diabetes mellitus, as defined by Hemoglobin A1C (Hb A1C ≥ 8).
• A current active, uncontrolled seizure disorder.
• Diagnosis of cancer, except for those participants who have undergone potentially curative therapy with no evidence of recurrence for > 5 years.
• History of alcoholism or substance abuse, current or within past 5 years.
• Previous exposure to Benfotiamine within past 3 months.
• Contraindication to MRI.
• Participation in another clinical trial for an investigational agent and having taken at least one dose of study drug, unless confirmed as having been on placebo, within 4 weeks prior to the baseline visit. The end of a previous investigational trial is defined as the date of the last dose of an investigational agent.
• Initiation of a monoclonal antibody treatment targeting brain amyloid within 6 months prior to the baseline visit.
• A disability that may prevent the patient from completing all study requirements e.g.,blindness, deafness, severe language difficulty).

Data sharing is integral to the ADCS's mission to develop and execute innovative clinical trials focused on interventions that may prevent, delay, or treat the expression of Alzheimer's disease and related dementias. The ADCS is committed to sharing resources and tools, including data, biospecimens, trial designs, outcome and analysis measures following NIH guidelines.

6 months after publication.

Data requestors must complete an ADCS data and sample sharing request form. Upon approval, requestors must complete a data use agreement prior to accessing the data.