Assess Fibrin in Brains With AD/ADRD

This study is using brain MRI to look for fibrin — a blood-clotting protein — in the brains of people with Alzheimer's disease and related dementias (ADRD), to understand whether this protein plays a role in the disease. **You may be eligible if...** - You are between 55 and 90 years old - You can give informed consent - Healthy volunteers: no history of Alzheimer's or related memory disorders - People with ADRD: have a diagnosis of Alzheimer's disease with mild cognitive impairment to moderate dementia, with a memory test score of 15 or higher (MMSE) or 12 or higher (MoCA) **You may NOT be eligible if...** - You have a pacemaker, metal implants, or other MRI contraindications - You have claustrophobia or other conditions preventing an MRI scan - You have significant neurological conditions other than ADRD Talk to your doctor to see if this trial is right for you.