A total of 61 high-resolution [18F]FEPPA PET scans were conducted in 28 individuals at clinical high risk (CHR) for psychosis, 19 First-Episode Psychosis (FEP), and 14 healthy volunteers (HVs), and analyzed using a two-tissue compartment model and plasma input function to obtain a total volume of distribution (VT) as an index of brain TSPO expression (controlling for the rs6971 TSPO polymorphism). This evidence concerns the gene TSPO and psychotic disorder.