Extending to studies on in vivo positron emission tomography (PET) imaging for the 18 kDa translocator protein (TSPO) in the living brains of psychotic patients, the field has generated mixed scenarios too, lacking solid evidence on myeloid activation and showing even consistently decreased rather than increased TSPO signal in psychosis including drug-free or recent-onset schizophrenia [56–59], which is also reminded (except in PET) in major depressive disorder [59, 60]. This evidence concerns the gene TSPO and major depressive disorder.