11C-PBR28 binding to translocator protein increases withprogression of Alzheimer’s disease

摘要

This longitudinal study sought to determine whether the 18 kDa translocator protein (TSPO), a marker of neuroinflammation, increases over time in Alzheimer’s disease. Positron emission tomography (PET) imaging with the TSPO radioligand ¹¹C-PBR28 imaging was performed at baseline and after a median follow-up of 2.7 years in 14 amyloid-positive patients and eight amyloid-negative controls. Patients had a greater increase in TSPO binding than controls in inferior parietal lobule, precuneus, occipital cortex, hippocampus, entorhinal cortex, and combined middle and inferior temporal cortex. TSPO binding in temporo-parietal regions increased 3.9 – 6.3% per annum in patients, but ranged from −0.5 – 1% per annum in controls.The change in TSPO binding correlated with cognitive worsening on Clinical Dementia Rating scale – Sum of Boxes and with reduced cortical volume. The annual rate of increased TSPO binding in temporo-parietal regions was about five-fold higher in patients with clinical progression (n = 9) compared to those who did not progress (n = 5). TSPO may serve as a biomarker of Alzheimer’s progression and response to anti-inflammatory therapies.