Trained clinicians with proper imaging techniques can diagnose AD correctly nearly 90% of the time.

Magnetic Resonance Imaging can measure the size of various structures in the brain.  Atrophy of the Hippocampus or other regions may be an early sign of AD.

Positron Emission Tomogrophy, and Single Photonemission Computed Tomography are able to visualize the activity in particular brain regions while they are being used during cognitive operations (e.g. memorizing, recalling, speaking, reading, etc.)  Reduced activity may be indicative of brain atrophy or nerve cell damage associated with AD.