Brain [ 18 F]FDDNP Binding and Glucose Metabolism in Advanced Elderly Healthy Subjects and Alzheimer's Disease Patients

Abstract

Background:

Positron emission tomography (PET) imaging of brain amyloid (Aβ) and neurofibrillary tangle (NFT) load is a candidate biomarker of Alzheimer’s disease (AD).

Objectives:

To compare brain Aβ and NFT load and glucose metabolism in advanced elderly (70 years and older) patients with AD and healthy controls (HCs) by PET with [¹⁸F]FDDNP and [¹⁸F]FDG.

Methods:

Seven AD patients (mean ± SD age 79.3 ± 3.6 y, Mini-Mental State Examination (MMSE) score 22.1 ± 2.5) and eight HCs (mean age ± SD, 75.7 ± 3.9 y; MMSE score 29.0 ± 1.2) underwent PET with [¹⁸F]FDDNP and [¹⁸F]FDG.

Results:

Global [¹⁸F]FDDNP uptake was significantly higher (p < 0.05) in AD patients (1.15 ± 0.04) than in HCs (1.10 ± 0.06), while global brain metabolism was lower in AD patients than in HCs (AD patients 0.96 ± 0.09; HCs 1.13 ± 0.11; p < 0.05). In HCs, brain glucose metabolism was correlated with age for both the global [¹⁸F]FDG SUVr and in the parietal and posterior cingulate regions, while no correlation was found between age and [¹⁸F]FDDNP uptake. In AD patients, global [¹⁸F]FDDNP uptake and uptake in the frontal and anterior cingulate regions of interest were correlated with MMSE score, while no correlation was observed with brain glucose metabolism.

Conclusion:

Imaging Aβ load and NFT with [¹⁸F]FDDNP can distinguish AD patients from HCs in an advanced elderly population. It seems to be less sensitive than [¹⁸F]FDG to the brain changes observed with normal aging, but more sensitive to cognitive decline in advanced elderly AD patients.