‘PET score’ Tops Neuropsych Testing in Tracking Alzheimer’s Progression

Positron emission tomography (PET) scans using F-18 florbetaben (18F-FDG) are more reliable than traditional neuropsychological testing in tracking the evolution of mild cognitive impairment to Alzheimer’s disease, researchers reported in the Journal of Nuclear Medicine.

A University of Manchester, U.K., team led by Karl Herholz developed a “PET score” based on scans of 94 patients with mild cognitive impairment (MCI), 40 patients with Alzheimer’s disease, and 44 controls. The subjects, part of the Alzheimer Disease Neuroimaging Initiative (ADNI), received four scans and clinical assessments over two years.

PET scores provided far higher test-retest reliability than standard neuropsychological scores done with the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-cog) and Mini-Mental State Examination. The scores also provided better measurements of progression, Herholz and colleagues found.

At the same time, FDG-PET scans relate directly to ADAS-cog scores, thus providing a valid measure of cognitive impairment. In addition, PET scores of patients who had mild cognitive impairment at the beginning of the study predicted clinical progression to dementia with a higher accuracy than Mini-Mental State Examination and ADAS-cog, the researchers reported.

FDG-PET provides insights into the impairment of synaptic function and could, with appropriate standardization, qualify as a biomarker, the researchers said.

"Prevention of dementia by drugs applied at MCI stage would greatly improve quality of life for patients and reduce costs of dementia care and treatment," Herholz and colleagues wrote.