Parbo P, et al. - Researchers evaluated the temporal and spatial inter-relationships between levels of cortical microglial activation and the aggregated amyloid-β and tau load in mild cognitive impairment (MCI) and early Alzheimer's disease (AD) with positron emission tomography (PET). No association was found between levels of cortical tau tangles and inflammation in the series of high amyloid-β cases, while correlated levels of amyloid-β and inflammation can be seen in MCI. Findings revealed that high levels of inflammation could be observed in amyloid-β positive MCI cases where ¹⁸F-flortaucipir signals were low, inferring that microglial activation precedes tau tangle formation. It was noted that inflammation levels were higher in high amyloid-β MCI than in early AD cases, consistent with it initially playing a protective role.