Visualizing Brain Proteinopathies Using [F-18]Flornaptitril-PET in the Prediction of Clinical Progression of Mild Cognitive Impairment With Either Suspected Chronic Traumatic Encephalopathy or Alzheimer's Disease

This study uses a specialized PET scan with a new imaging agent called [F-18]flornaptitril to visualize abnormal protein buildup in the brains of people with mild cognitive impairment (MCI). The goal is to determine whether this scan can detect signs of either chronic traumatic encephalopathy (CTE — brain injury from repeated head trauma) or Alzheimer's disease before significant memory loss sets in. **You may be eligible if...** - You are 45 or older with MCI suspected to be related to CTE, or 50 or older with MCI suspected to be related to Alzheimer's disease - You have a trusted companion (friend or family member) who sees you at least 3–4 times per week and can attend all clinic visits with you - Female participants must be post-menopausal or surgically sterilized **You may NOT be eligible if...** - You do not have a regular companion able to assist with study visits - You have other neurological conditions that may explain your cognitive symptoms - You do not meet the specific MCI diagnostic criteria for this study Talk to your doctor to see if this trial is right for you.