A system for using functional magnetic resonance imaging (fMRI) for detecting symptoms indicative of Alzheimer's disease, diagnosing Alzheimer's disease and gauging the efficacy of medications used in treating Alzheimer's disease. The system includes steps involving activating a selected region of the brain which may be affected by Alzheimer's disease using an identity recognition type task, concurrently acquiring task-active MRI data responsive to the task, comparing the patient's task-active MRI data to reference data derived from a database of task-active data from healthy individuals and detecting whether the patient has symptoms related to Alzheimer's disease. The severity of the patient's symptoms and the staging of the disease may also be determined. Also, a medication may be administered to the patient and the efficacy of the medication may be gauged based on the severity of the patient's symptoms.