Brain NAD in Alzheimer's Disease

The goal of this observational study is to learn about the levels of nicotinamide adenine dinucleotide (NAD) in the brains of people with Alzheimer's disease. The study aims to determine if brain NAD levels are lower in people with Alzheimer's disease compared with people of the same age group who do not have Alzheimer's disease. Participants with or without Alzheimer's disease will have a brain imaging session where NAD will be measured using magnetic resonance spectroscopy (MRS). Eight months later, they will have a second, similar, brain imaging session.