Upregulation of MAO-B is a marker of reactive astrocytes and is more cell-type selective than TSPO, suggesting the potential for measuring alteration in MAO-B-PET levels as a marker of astrocytosis in diseases such as Alzheimer’s disease and related dementias.36 In CTE, mRNA transcripts associated with neuroinflammation were elevated in CTE astrocyte groups compared with HCs, suggesting that white matter alterations are a critical aspect of CTE neurodegeneration.60 Herein, [3H]L-deprenyl was used to establish the localization of astrocytic cells in human post-mortem CTE tissues. This evidence concerns the gene TSPO and early-onset autosomal dominant Alzheimer disease.