After two years, [18F]FDDNP binding values significantly increased in the frontal, parietal, posterior cingulate, and global regions of the patients with mild cognitive impairment. Patients with normal aging did not display any increases in binding values. Patients with increased global binding at follow-up showed significantly greater memory decline than did patients without increased global binding. For all patients, higher levels of [18F]FDDNP binding at baseline were associated with larger decreases in executive function, language, attention, and visuospatial function at follow-up.
Six of the 21 patients with mild cognitive impairment at baseline had developed Alzheimer’s disease at follow-up. These six patients had higher frontal, parietal, and global [18F]FDDNP binding values at baseline than the other patients with mild cognitive impairment did. Three patients with normal aging developed mild cognitive impairment by the time of follow-up, and two of them had the highest regional [18F]FDDNP signals at baseline in the normal aging group.
[18F]FDDNP regional binding patterns “are consistent with known neuropathologic patterns of plaque and tangle brain accumulation,” wrote Dr. Small and colleagues. “Because binding patterns predict future cognitive decline and increase over time along with clinical decline, [18F]FDDNP PET scanning may have practical utility in identifying people at risk for future cognitive decline,” they concluded.
Small GW, Siddarth P, Kepe V, et al. Prediction of cognitive decline by positron emission tomography of brain amyloid and tau. Arch Neurol. 2012;69(2):215-222.