TSPO and Parkinson disease: Several studies have observed an increase of TSPO binding in the midbrain, striatum or cortex of PD mainly using the first-generation TSPO tracer 11C-(R)-PK11195 [12–16] or the second-generation tracers 11C-DPA713/18F-DPA714 [17, 18], while some other studies showed a lack of binding differences between PD and healthy controls using the second-generation TSPO tracers 18F-FEPPA or 11C-PBR28 [19–21].