"AD pathology marches through the brain many years before we can diagnose it - which is unsettling," Dr. Liana G. Apostolova told Reuters Health. "These avant-garde neuroimaging advances deliver a promise that pre-clinical diagnosis of AD will soon be feasible."

Dr. Apostolova from the David Geffen School of Medicine, University of California at Los Angeles, and associates used 3-D cortical mapping to analyze structural MRI data for 24 patients with amnestic MCI and 25 patients with mild AD.

Patients with mild AD showed 10% to 15% greater gray matter atrophy in most of the cortex than did patients with amnestic MCI, the authors report.

Atrophy was more than 15% greater in the bilateral entorhinal, right more than left lateral temporal, right parietal cortex, and bilateral precuneus areas.

In both groups of patients, the researchers note, there was less cortical gray matter in the right hemisphere than in the left hemisphere.

"With several promising disease-modifying candidate compounds under development, being able to discern subtle structural cortical changes between mild AD and the immediately preceding cognitive state of amnestic MCI with anatomical precision raises hopes for our ability to show structural disease-modifying effects," the investigators say.

"At this point these analysis methods are largely a research tool, but we are hopeful in the near future to develop software techniques that could be useful in the clinic," Dr. Apostolova said. "Our new maps reveal the systems that change with the gradual descent to AD, and we hope to compare individual imaging findings to these maps to help understand future prognosis."