All patients will have an advanced MRI of the brain to include volume measurement of the hippocampus (ref 22), arterial spin labeling (ASL) perfusion scan (ref 23) and MRS of prefrontal, precuneus, hippocampus and occipital lobe. Patients with cognitive decline have decreased perfusion in temporal parietal or frontal regions of the brain with ASL perfusion, or show characteristic change in MRS or volumetric evaluation compared to aged matched control subjects. MRI will also demonstrate if patients have tumors, hydrocephalus, subdural hematomas and other structural etiologies of cognitive decline.