This clinical trial is studying a drug called **Benfotiamine** to see if it can help people with early Alzheimer's disease. Alzheimer's is a condition that affects memory and thinking. Benfotiamine might help slow down symptoms. The study will last **18 months**, and it involves two phases: **Phase 2A** and **Phase 2B**. During Phase 2A, participants will receive either 600 mg, 1200 mg of Benfotiamine, or a **placebo** (a pill that doesn’t contain the drug) to find the best dose. Phase 2B will then test the effectiveness of the chosen dose over 72 weeks. To join, you must be between **50 and 89 years old** and have mild memory problems due to Alzheimer's. You need a buddy who can help and attend visits with you. You also need to be able to walk and speak English or Spanish. **Some medical conditions may prevent you from joining**, like other serious brain diseases or uncontrolled diabetes. **Key Points:** - **Duration**: 18 months with multiple visits. - **Eligibility**: Ages 50-89, early Alzheimer's symptoms. - **Participation**: Must have a study partner and be able to attend visits.